CN106775438A - A kind of I/O dispatching methods based on solid-state disk read write attribute - Google Patents
A kind of I/O dispatching methods based on solid-state disk read write attribute Download PDFInfo
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- G06F3/06—Digital input from, or digital output to, record carriers, e.g. RAID, emulated record carriers or networked record carriers
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Abstract
The invention discloses a kind of I/O dispatching methods based on solid-state disk difference read write attribute.The optimal merging in solid-state disk inside is obtained by way of Black-box Testing and asks page size that clusters；Read-write requests are separated, processes read request and write request in bulk respectively to avoid reading and writing in composite mode interfering in solid-state disk；Performance in view of read request under ordered mode is significantly larger than the performance of read request under stochastic model, the time that read request not only arrives according to request is queued up in chained list, sorted in RBTree according further to the initial reference address of read request, to construct the succession of read request, to merging and merging backward before read request after sequence is carried out, the largest amount asked after merging is no more than page size that clusters；Performance in view of write request under the performance and stochastic model of write request under ordered mode is essentially identical, and the time that write request only needs to be arrived according to request queues up in chained list, it is not necessary to the succession of the construction write request that sorted in RBTree.
Description
Technical field
The invention belongs to solid-state disk technical field of memory, solid-state disk is based on not more particularly, to one kind
With the I/O dispatching methods of read write attribute.
Background technology
Solid-state disk (Solid state disk, abbreviation SSD) be it is a kind of by the use of nand flash memory chip as
The hard disk that data are permanently stored, the production cost with nand flash memory chip declines, the price of SSD
Also increasingly received by people, SSD sets in data center, PC, various types of movements
Standby upper use is more and more extensive.But, because the equipment for building storage system for a long time is all hard
Disk drive (Hard disk drive, abbreviation HDD), most of existing systems soft ware be towards
HDD is designed and optimizes, and directly using SSD replacing HDD can not send out to greatest extent
Wave the high-performance of SSD.Therefore, systems soft ware optimization tool is carried out for SSD to be of great significance.
HDD is a kind of hard disk of machinery rotating type, and its read-write operation mainly has following steps：
1st, seek：All of magnetic head is moved to cylinder to be visited by magnetic head transmission device, and acquisition is worked as
Before the head number that needs to use；2nd, rotational latency：After navigating to corresponding card and magnetic track, card is just
Can rotate, during rotation, magnetic head can be read in the sector leader in the sector immediately below it
Information, compares with the sector number of read/write is needed, and card may proceed to rotation if mismatching,
If matching if since this sector read/write data；3rd, reading and writing data is completed.HDD read-write operations are very
Big portion of time consumption is on tracking and rotational latency, and the I O scheduling algorithm institute in linux kernel
The optimization done is main also for the time loss for reducing tracking and rotational latency.
In linux system, existing I O scheduling algorithm is mainly Noop algorithms, CFQ algorithms
Deadline algorithms and Anticipatory algorithms.Wherein CFQ, Deadline and Anticipatory are calculated
Method is long for the HDD tracking times, takes the continuous read-write requests of merging, thus can be in tracking
Continuously read and write after end.Noop algorithms are refused read-write requests to merge, and only insert new request
Enter tail of the queue.
However, there is following aspect in above-mentioned I O scheduling algorithm：1st, in SSD, order
Write essentially identical with random write performance, so write request is merged, and the speed of SSD can not be improved
Rate, can influence the performance of system on the contrary；2nd, in SSD, on the premise of no more than page size that clusters
Merging read request can just improve reading efficiency, and read request size can't improve reading after exceeding page size that clusters
Efficiency.
The content of the invention
For the disadvantages described above or Improvement requirement of prior art, solid-state disk is based on the invention provides one kind
The I/O dispatching methods of different read write attributes, it is intended that solving to exist in existing I O scheduling method
Continuous read request merge after it is excessive or can not be merged and write request has unnecessary merging
Technical problem.
To achieve the above object, according to one aspect of the present invention, there is provided a kind of to be read based on solid-state disk
The I O scheduling method of write attribute, comprises the following steps：
(1) receive from upper layer application and by the bio requests after file system treatment, and judge the bio
The type of request is read request or write request, if read request is then transferred to step (2), if
Write request is then transferred to step (3)；
(2) judge the read request whether can read request adjacent thereto merge, if can not merge,
Then directly it is transferred to step (4)；If the size after can merging and merging is no more than the size of the page that clusters,
Then it is merged with neighbouring read request, the read request after merging still can be with reading adjacent thereto
Request is merged, and should be ensured that the size after merging is no more than the size of the page that clusters.Will be final
Read request after merging is put into reading queue and reading RBTree, so that system reads data.Then it is transferred to
Step (4).
(3) judge whether the write request can merge with the write request in caching, if can if
Merge, and by the write request insertion dispatcher queue end after merging, and it is transferred to step (4)；
Otherwise judge that can it merge with the write request in Hash table, if can if merge, and
Write request insertion dispatcher queue end after just merging, and it is transferred to step (4)；
(4) request in dispatcher queue is distributed in the request queue of device driver.
Preferably, step (2) includes following sub-step：
(2.1) for the read request, the read request of last time merging is judged whether, if in the presence of,
Jump to step (2.2)；Otherwise jump to step (2.3)；
(2.2) judge the read request merged with last time after read request can merge.If can not
Merge, then jump to step (2.3), if preceding step (2.4) can be jumped to merging, if
Can backward merge, then jump to step (2.5)；
(2.3) judge that can the read request be merged backward with the request in ltsh chain table, if energy
Then jump to step (2.5)；Otherwise jump to step (2.6)；
(2.4) complete can the forward direction read request Rfrq and the read request that merge merge, and judge it is preceding to
Can the read request Rfrq after merging continue and read to be visited according to the starting of request in RBTree in scheduler
Ask the previous read request Rprev of the Rfrq of address sort before proceeding to merging.Step can then be jumped to
Suddenly (2.7), step (2.8) is otherwise jumped to；
(2.5) merging for the request Rbrq that can merge backward and the read request is completed, and judges conjunction backward
And can request Rbrq afterwards continue and the initial access in reading RBTree in scheduler according to request
The latter request Rnext of the Rbrq of location sequence proceeds backward merging.Step can then be jumped to
(2.9) step (2.10), is otherwise jumped to；
(2.6) to merging before judging the read request and being carried out with the request read in scheduler in RBTree,
If can if jump to step (2.4), otherwise jump to step (2.11)；
(2.7) read request Rfrq is completed to merge with the forward direction of read request Rperv, deletion scheduler reading queue,
Read the Rfrq requests in RBTree and generic block layer ltsh chain table；Simultaneously according to the read request being merged
Size changes positions of the Rprev in ltsh chain table；And by merging after service time the latest be set to
Less one in the service time the latest of Rfrq and Rprev；The read request mark that finally last time was merged
It is Rfrq.
(2.8) read request that last time merges is set to Rfrq, and updates Rfrq's in RBTree is read
Initial address；
(2.9) complete request Rbrq to merge with request the backward of Rnext, reading queue, reading in scheduler
Rnext requests are deleted in the ltsh chain table of RBTree and generic block layer, Rbrq requests is updated in hash chain
Position in table, by service time is set to the clothes of the read request after merging earlier in Rbrq and Rnext
The business time, the read request that Rbrq was merged labeled as last time, and jump to step (2.14)；
(2.10) read request for merging Rbrq labeled as last time, and Rbrq requests are updated in ltsh chain table
In position, terminate conversion；
(2.11) it is one request Rnrq of bio requests distribution, and initialization Rnrq is asked with the bio,
And judge whether Rnrq has merging attribute, if then jumping to step (2.12)；Otherwise jump to
Step (2.13)；
(2.12) Rnrq requests are added into ltsh chain table, and judges whether the read request of last time merging.
If it is present jumping directly to step (2.13)；The reading for otherwise first merging Rnrq labeled as last time
Request, and jump to step (2.13)；
(2.13) will Rnrq request add scheduler in read queue end and read RBTree in.
Preferably, step (3) includes following sub-step：
(3.1) for the write request, the write request of last time merging is judged whether, if it does,
Jump to step (3.2)；Otherwise jump to step (3.3)；
(3.2) judge whether the write request that can merge with last time is merged for bio requests, if energy
To merging before enough, step (3.4) is jumped to；If can be merged backward, step (3.5) is jumped to；
If can not merge that step (3.3) is jumped to；
(3.3) judge that can bio requests be merged backward with the request in ltsh chain table, if energy
Then jump to step (3.5)；Otherwise jump to step (3.6)；
(3.4) to merging before the write request that bio requests merged with last time is carried out, and merging is judged
Can also continue afterwards with chained list is write in scheduler in its previous request Wprev proceed to merge.If
Can merge with Wprev, then jump to step (3.7), otherwise jump to step (3.8)；
(3.5) the backward merging of bio requests and the request Wbrq that can merge backward is completed, and judges to merge
Next request Wnext that can Wbrq afterwards write Wbrq in chained list with scheduler proceeds to close
And.Step (3.9) can then be jumped to；Otherwise jump to step (3.10)；
(3.6) it is one new request Wnrq of bio requests distribution, and initialization Wnrq is asked with the bio.
Then judge whether Wnrq has and merge attribute.Have, jump to step (3.11)；Otherwise jump to step
Suddenly (3.12)；
(3.7) complete merging for Wfrq and Wprev, and chained list, ltsh chain table are write in scheduler
Wfrq is deleted, then needs to adjust positions of the Wprev in ltsh chain table, be finally labeled as Wprev
The write request that last time merges, terminates this conversion by bio request conversions for write request；
(3.8) write request for merging Wfrq labeled as last time, by bio request conversions in order to write
Request, terminates this conversion；
(3.9) complete merging for Wbrq and Wnext, and write chained list, ltsh chain table in scheduler is deleted
Except Wnext, then need to adjust positions of the Wbrq in ltsh chain table, finally by Wbrq labeled as upper
The write request of secondary merging, terminates this conversion by bio request conversions for write request；
(3.10) positions of the adjustment Wbrq in ltsh chain table, and by Wbrq labeled as last time merging
Write request, terminates this conversion by bio request conversions for write request；
(3.11) by Wnrq add ltsh chain table in, and judge last time merge write request whether there is.
If not existing, the write request that Wnrq was merged labeled as last time, and jump to step (3.12)；It is no
Then, step (3.12) is leapt to；
(3.12) Wnrq addition schedulers are write into the afterbody of chained list, so as to by the bio ask conversion in order to
Write request.
Preferably, step (4) includes following sub-step：
(4.1) judge that the stage distributed at present residing for request in dispatcher queue is in reading batch processing rank
Section still writes batch phase, if in batch phase is read, jumping to step (4.2)；If
In batch phase is write, then step (4.3) is jumped to,
(4.2) judge whether the request sum for reading batch phase distribution has exceeded threshold value.If having exceeded
Threshold value, then jump to step (4.4), otherwise jumps to step (4.5)；
(4.3) judge whether the request sum for writing batch phase distribution has reached the upper limit, if having reached the upper limit,
Step (4.4) is jumped to, step (4.6) is otherwise jumped to；
(4.4) batch phase is created, and determines to whether there is corresponding reading in dispatcher queue
Request, if in the presence of jumping to step (4.9)；Otherwise jump to step (4.10)；
(4.5) request Drq to be distributed in scheduler is set to next_rq [read], and jumps to step
Suddenly (4.7)；
(4.6) request Drq to be distributed in scheduler is set to next_rq [write], and jumps to step
Suddenly (4.8)；
(4.7) Drq is distributed in the request queue of device drive layer, from the reading chained list of scheduler and reading
Delete the Drq in RBTree, and next_rq [read] is set to Drq and read RBTree in scheduler
Next request, finally counts to the operation, terminates this request distribution procedure；
(4.8) Drq is distributed in the request queue of device drive layer, from scheduler write chained list in delete
Except Drq, it is next requests of the Drq in scheduler writes chained list to set next_rq [write], finally to this
Operation is counted, and terminates this request distribution procedure；
(4.9) writing with the presence or absence of request in chained list, if it does not exist, then jumping to for scheduler is judged
Step (4.11)；If it is present continuing to determine whether the write request or write request quilt that there is time-out
Hungry number of times has reached the upper limit, if it is decided that result is true, then jump to step (4.12)；Otherwise jump
Go to step (4.11)；
(4.10) writing with the presence or absence of request in chained list for scheduler is judged, if in the presence of jumping to step
(4.12)；Do not exist request to be distributed otherwise in scheduler, terminate this request distribution procedure；
(4.11) judge that next_rq [read] whether there is.If in the presence of jumping to step (4.13)；It is no
Then jump to step (4.14)；
(4.12) write request is set to 0 by hungry number of times.Then the write request of time-out is judged whether
Or whether next_rq [write] is empty.If it is determined that result is true, step (4.15) is jumped to；It is no
Person jumps to step (4.16)；
(4.13) request Drq to be distributed is set to next_rq [read], batching=0 is set, started
A reading batch phase is created, step (4.7) is jumped to；
(4.14) request Drq to be distributed is set to first request in scheduler reading chained list, is set
Batching=0, starts to create a reading batch phase, jumps to step (4.7)；
(4.15) request Drq to be distributed is set to scheduler and writes first in chained list request, set
Batching=0, starts establishment one and writes batch phase, jumps to step (4.8)；
(4.16) request Drq to be distributed is set to next_rq [write], batching=0 is set,
Start establishment one and write batch phase, jump to step (4.8).
In general, by the contemplated above technical scheme of the present invention compared with prior art, can
Obtain following beneficial effect：
(1) present invention can solve the problem that continuous read request present in existing method is excessive after merging or not
The problem of merging：As a result of step (2.2) step (2.4) step (2.5) and step (2.7),
Therefore can solve in existing Noop algorithms to read request nonjoinder, and CFQ, Deadline,
Excessive problem is merged to read request in Anticipatory algorithms.
(2) present invention can solve the problem that merging unnecessary to continuous write request present in existing method
Problem：As a result of step (3.4) step (3.5) step (3.7) and step (3.9),
Therefore can solve the problems, such as to merge continuous write request in existing I O scheduling algorithm.
(3) present invention makes full use of solid-state disk readwrite performance under different access pattern：In view of SSD
The performance of read request is significantly larger than the performance of read request under stochastic model under middle ordered mode, to read request
The time for not only being arrived according to request queues up in chained list, and the initial reference address according further to read request exists
Sorted in RBTree, to construct the succession of read request, to conjunction before being carried out to the read request after sequence
And and backward merging；In view of the property of write request under the performance and stochastic model of write request under ordered mode
Can be essentially identical, the time that write request only needs to be arrived according to request queues up in chained list, it is not necessary to
The succession of the construction write request that sorted in RBTree, is also only merged backward to write request.
(4) present invention makes full use of the abundant concurrency of solid-state disk：When merging read-write requests, it is contemplated that
Minimum read-write operation unit is page in SSD, and in order to using the concurrency inside SSD, read-write behaviour
It is likely to be with the page as minimum operation unit that clusters, the page that clusters is obtained by way of Black-box Testing
Size, and when merging request, it is ensured that size of the request no more than the page that clusters after merging.Work as request
Size is reached when clustering page size, continues to merge request, will not bring the lifting of performance, can be made on the contrary
Into SSD equipment idle waitings, performance is reduced.
Brief description of the drawings
Fig. 1 is the I/O paths that (SuSE) Linux OS solid-state disk is accessed.
Fig. 2 is the flow chart of I/O dispatching method of the present invention based on solid-state disk difference read write attribute.
Fig. 3 is the transformation of reading bio requests to request in this dispatching method.
Fig. 4 is the transformation that bio requests to request are write in this dispatching method.
Fig. 5 is to distribute request to device drive layer in this dispatching method.
Specific embodiment
In order to make the purpose , technical scheme and advantage of the present invention be clearer, below in conjunction with accompanying drawing
And embodiment, the present invention will be described in further detail.It should be appreciated that described herein specific
Embodiment is only used to explain the present invention, is not intended to limit the present invention.Additionally, disclosed below
As long as in each implementation method of the invention involved technical characteristic do not constitute conflict each other can
To be mutually combined.
As shown in figure 1, upper layer application calls the I/O Request of module for reading and writing initiation by system, first can
Truly need to visit by virtual file system (Virtual file system, abbreviation VFS), and arrival
The file system layer asked, then can finally reach scsi device by generic block layer and I O scheduling layer
Layer is driven, could be to bottom disk requests data.I/O of the present invention based on solid-state disk difference read write attribute
Dispatching method is operated in I/O dispatch layers.Specifically complete following two functions：
1st, the bio requests for coordinating generic block layer to issue file system layer are packaged into according to certain strategy
Request, and add the request queue of dispatch layer；
2nd, by I O scheduling layer request queue in request according to certain strategy distribution to lower floor SCSI
In the request queue of device drive layer.So that the read request for reaching solid-state disk is presented stronger succession,
Can appropriateness ground be using the concurrency inside solid-state disk and avoids mutually dry between read-write requests
Disturb such that it is able to improve the I/O performances of whole solid-state disc system.
Integral Thought of the invention is, it has taken into full account interfering for read-write requests in solid-state disk,
Read-write requests are separated, batch processing read request and write request；In view of read request under ordered mode
Performance is significantly larger than the performance of read request under stochastic model, to read request not only according to request arrive when
Between in chained list queue up, sort in RBTree according further to the initial reference address of read request, with construction
The succession of read request, to merging and backward merging before being carried out to the read request after sequence；Consider
The performance of write request is essentially identical under the performance and stochastic model of write request under ordered mode, and write request is only
The time arrived according to request is needed to be queued up in chained list, it is not necessary to which the construction that sorted in RBTree is write please
The succession asked, is also only merged backward to write request；It is available in view of being existed in solid-state disk
Optimal Parallel degree, when merge request reach cluster page size when, do not go on merging, request reaches
To cluster page size when can make full use of the concurrency enriched in solid-state disk, continue to merge request,
Performance boost will not be brought, SSD equipment idle waitings can be caused on the contrary, reduce performance.
The present invention specifically completes following two functions in the I/O dispatch layers realization of linux kernel：1、
The bio requests for coordinating generic block layer to issue file system layer are packaged into request according to certain strategy, and
Add the request queue of dispatch layer；2nd, by the request in I O scheduling layer request queue according to certain plan
Slightly it is distributed in the request queue that the scsi device of lower floor drives layer.So that reaching the read request of solid-state disk
Stronger succession is presented, can appropriateness ground be using the concurrency inside solid-state disk and avoids reading
Interfering between write request such that it is able to improve the I/O performances of whole solid-state disc system.
As shown in Fig. 2 I O scheduling method of the present invention based on solid-state disk read write attribute is comprised the following steps：
(1) receive from upper layer application and by file system (in the present embodiment, this document system
System is ext4 file system) treatment after bio request, and judge the bio request type be read request also
It is write request, if read request is then transferred to step (2), if write request is then transferred to step (3)；
(2) judge the read request whether can read request adjacent thereto merge, if can not merge,
Then directly it is transferred to step (4)；If the size after can merging and merging is no more than the size of the page that clusters,
Then it is merged with neighbouring read request, the read request after merging still can be with reading adjacent thereto
Request is merged, and should be ensured that the size after merging is no more than the size of the page that clusters.Will be final
Read request after merging is put into reading queue and reading RBTree, so that system reads data.Then it is transferred to
Step (4).
(3) judge whether the write request can merge with the write request in caching, if can if
Merge, and by the write request insertion dispatcher queue end after merging, and it is transferred to step (4)；
Otherwise judge that can it merge with the write request in Hash table, if can if merge, and
Write request insertion dispatcher queue end after just merging, and it is transferred to step (4)；
(4) request in dispatcher queue is distributed in the request queue of device driver, process knot
Beam.
As shown in figure 3, the step (2) in the inventive method includes following sub-step：
(2.1) for the read request, the read request of last time merging is judged whether, if in the presence of,
Jump to step (2.2)；Otherwise jump to step (2.3)；
(2.2) judge the read request merged with last time after read request can merge.If can not
Merge, then jump to step (2.3), if preceding step (2.4) can be jumped to merging, if
Can backward merge, then jump to step (2.5)；Specifically, if the read request and previous read request
It is continuous on address, and request size after merging is no more than clustering a page size, then it represents that energy
To merging before enough, if the address of the read request is continuous on address with latter read request, and close
And after read request size no more than clustering a page size, then it represents that can merge backward；
The advantage of this step is：By caching the last request for merging, hardly increasing expense
In the case of can greatly shorten the time delay of request searched and can merge with current read request, improve merging
The efficiency of request, increases performance；The size asked after merging in addition, can no more than page size that clusters
With the concurrency for making full use of SSD inside abundant, it is unlikely to excessively to merge again and causes SSD equipment free time etc.
Treat, can further improve performance；
(2.3) judge that can the read request be merged backward with the request in ltsh chain table, if energy
Then jump to step (2.5)；Otherwise jump to step (2.6)；
(2.4) complete can the forward direction read request Rfrq and the read request that merge merge, and judge it is preceding to
Can the read request Rfrq after merging continue and read to be visited according to the starting of request in RBTree in scheduler
Ask the previous read request Rprev of the Rfrq of address sort before proceeding to merging.Step can then be jumped to
Suddenly (2.7)；Otherwise jump to step (2.8)；
(2.5) merging for the request Rbrq that can merge backward and the read request is completed, and judges conjunction backward
And can request Rbrq afterwards continue and the initial access in reading RBTree in scheduler according to request
The latter request Rnext of the Rbrq of location sequence proceeds backward merging.Step can then be jumped to
(2.9) step (2.10), is otherwise jumped to；
(2.6) to merging before judging the read request and being carried out with the request read in scheduler in RBTree,
If can if jump to step (2.4), otherwise jump to step (2.11)；
(2.7) read request Rfrq is completed to merge with the forward direction of read request Rperv, deletion scheduler reading queue,
Read the Rfrq requests in RBTree and generic block layer ltsh chain table；Simultaneously according to the read request being merged
Size changes positions of the Rprev in ltsh chain table；And by merging after service time the latest be set to
Less one in the service time the latest of Rfrq and Rprev；The read request mark that finally last time was merged
It is Rfrq, this EOC.Specifically, above step is exactly to delete the pair for being merged rear read request
This, and the service time of the read request after merging and the position in ltsh chain table are adjusted, and record
The address of the read request that last time merges；
The advantage of this step is：By preceding to merging, small request can be aggregated into big request, can
To greatly improve the handling capacity of system；
(2.8) read request that last time merges is set to Rfrq, and updates Rfrq's in RBTree is read
Initial address；
(2.9) complete request Rbrq to merge with request the backward of Rnext, reading queue, reading in scheduler
Rnext requests are deleted in the ltsh chain table of RBTree and generic block layer, Rbrq requests is updated in hash chain
Position in table, by service time is set to the clothes of the read request after merging earlier in Rbrq and Rnext
The business time, the read request that Rbrq was merged labeled as last time, and jump to step (2.14)；
The advantage of this step is：By backward merging, small request can be aggregated into big request, can
To greatly improve the handling capacity of system；
(2.10) read request for merging Rbrq labeled as last time, and Rbrq requests are updated in ltsh chain table
In position；Terminate conversion；
(2.11) it is one request Rnrq of bio requests distribution, and initialization Rnrq is asked with the bio,
And judge whether Rnrq has merging attribute, if then jumping to step (2.12)；Otherwise jump to
Step (2.13)；
(2.12) Rnrq requests are added into ltsh chain table, and judges whether the read request of last time merging.
If it is present jumping directly to step (2.13)；The reading for otherwise first merging Rnrq labeled as last time
Request, and jump to step (2.13)；
(2.13) will Rnrq request add scheduler in read queue end and read RBTree in；
The advantage of this step is：Set read request needs the being serviced time the latest, and Priority Service surpasses
When read request, it is to avoid a certain read request cannot be serviced for a long time；In addition to read request not only according to please
Ask the time of arrival to be queued up in chained list, arranged in RBTree according further to the initial reference address of read request
Sequence, to construct the succession of read request, with making full use of under ordered mode far superior to stochastic model
Reading performance；
As shown in figure 4, the step (3) in the inventive method includes following sub-step：
(3.1) for the write request, the write request of last time merging is judged whether, if it does,
Jump to step (3.2)；Otherwise jump to step (3.3)；
(3.2) judge whether the write request that can merge with last time is merged for bio requests, if energy
To merging before enough, step (3.4) is jumped to；If can be merged backward, step (3.5) is jumped to；
If can not merge that step (3.3) is jumped to；
The advantage of this step is：By caching the last request for merging, hardly increasing expense
In the case of can greatly shorten the time delay of request searched and can merge with current bio requests, improve merging
The efficiency of request, increases performance；The size asked after merging in addition, can no more than page size that clusters
With the concurrency for making full use of SSD inside abundant, it is unlikely to excessively to merge again and causes SSD equipment free time etc.
Treat, can further improve performance；
(3.3) judge that can bio requests be merged backward with the request in ltsh chain table, if energy
Then jump to step (3.5)；Otherwise jump to step (3.6)；
(3.4) to merging before the write request that bio requests merged with last time is carried out, and merging is judged
Can also continue afterwards with chained list is write in scheduler in its previous request Wprev proceed to merge.If
Can merge with Wprev, then jump to step (3.7), otherwise jump to step (3.8)；
(3.5) the backward merging of bio requests and the request Wbrq that can merge backward is completed, and judges to merge
Next request Wnext that can Wbrq afterwards write Wbrq in chained list with scheduler proceeds to close
And.Step (3.9) can then be jumped to；Otherwise jump to step (3.10)；
The advantage of this step is：By backward merging, small request can be aggregated into big request, can
To greatly improve the handling capacity of system；
(3.6) it is one new request Wnrq of bio requests distribution, and initialization Wnrq is asked with the bio.
Then judge whether Wnrq has and merge attribute.Have, jump to step (3.11)；Otherwise jump to step
Suddenly (3.12)；
(3.7) complete merging for Wfrq and Wprev, and chained list, ltsh chain table are write in scheduler
Wfrq is deleted, then needs to adjust positions of the Wprev in ltsh chain table, be finally labeled as Wprev
The write request that last time merges, terminates this conversion by bio request conversions for write request；
(3.8) write request for merging Wfrq labeled as last time, by bio request conversions in order to write
Request, terminates this conversion；
(3.9) complete merging for Wbrq and Wnext, and write chained list, ltsh chain table in scheduler is deleted
Except Wnext, then need to adjust positions of the Wbrq in ltsh chain table, finally by Wbrq labeled as upper
The write request of secondary merging, terminates this conversion by bio request conversions for write request；
(3.10) positions of the adjustment Wbrq in ltsh chain table, and by Wbrq labeled as last time merging
Write request, terminates this conversion by bio request conversions for write request；
(3.11) by Wnrq add ltsh chain table in, and judge last time merge write request whether there is.
If not existing, the write request that Wnrq was merged labeled as last time, and jump to step (3.12)；It is no
Then, step (3.12) is leapt to；
(3.12) Wnrq addition schedulers are write into the afterbody of chained list, so as to by the bio ask conversion in order to
Write request；
The advantage of this step is：Fully take into account the performance and random write request of order write request in SSD
Performance it is essentially identical, write request is queued up only according to the time of arrival in chained list, it is not necessary to according to writing
The initial reference address of request sorts in RBTree, constructs the succession of write request, eliminates sequence
Performance cost, improve performance；
As shown in figure 5, the step (4) in the inventive method includes following sub-step：
(4.1) judge that the stage distributed at present residing for request in dispatcher queue is in reading batch processing rank
Section still writes batch phase.If in batch phase is read, jumping to step (4.2)；If
In batch phase is write, then step (4.3) is jumped to；Specifically, exactly transported by obtaining program
The value of next_rq [dir] variable is come to judge distribution request be at reading batch phase or writing batch during row
The reason stage.The advantage of this step is：Batch distribution read request or write request, it is to avoid read-write please in SSD
The hydraulic performance decline that interfering between asking is caused；
(4.2) judge whether the request sum for reading batch phase distribution has exceeded threshold value.If having exceeded
Threshold value, then jump to step (4.4), otherwise jumps to step (4.5)；In the present invention, the threshold value
Span be (0,16].
(4.3) judge whether the request sum for writing batch phase distribution has reached the upper limit, if having reached the upper limit,
Jump to step (4.4)；Otherwise jump to step (4.6)；
(4.4) batch phase is created, and determines to whether there is corresponding reading in dispatcher queue
Request, if in the presence of jumping to step (4.9)；Otherwise jump to step (4.10)；
(4.5) request Drq to be distributed in scheduler is set to next_rq [read], and jumps to step
Suddenly (4.7)；
(4.6) request Drq to be distributed in scheduler is set to next_rq [write], and jumps to step
Suddenly (4.8)；
(4.7) Drq is distributed in the request queue of device drive layer, from the reading chained list of scheduler and reading
Delete the Drq in RBTree, and next_rq [read] is set to Drq and read RBTree in scheduler
Next request, finally counts to the operation, terminates this request distribution procedure；
The advantage of this step is：Batch distribution read request phase, next reading is obtained from red-black seeds
Request, using the ranking function of RBTree, to construct the succession of read request, makes full use of suitable in SSD
The performance that sequence is read is significantly larger than the performance of random write；
(4.8) Drq is distributed in the request queue of device drive layer, from scheduler write chained list in delete
Except Drq, it is next requests of the Drq in scheduler writes chained list to set next_rq [write], finally to this
Operation is counted, and terminates this request distribution procedure；
The advantage of this step is：In the batch distribution write request stage, next writing is obtained from chained list please
Ask, it is not necessary to construct the succession of write request, so as to eliminate the expense of sequence, make full use of SSD
Performance of the performance of middle random write substantially with sequential write is identical；
(4.9) writing with the presence or absence of request in chained list, if it does not exist, then jumping to for scheduler is judged
Step (4.11)；If it is present continuing to determine whether the write request or write request quilt that there is time-out
Hungry number of times has reached the upper limit.If it is determined that result is true, then step (4.12) is jumped to；Otherwise jump
Go to step (4.11)；
The advantage of this step is：The preferential batch distribution procedure for creating read request, assign read request compared with
Priority high, has met user's demand stricter to read request response time requirement, in addition for
Prevent write request from being died of hunger, to be also provided with write request need the time of being serviced the latest, please when writing
When seeking time-out, the write request of preferential distribution time-out；
(4.10) writing in chained list with the presence or absence of request for scheduler is judged.If in the presence of jumping to step
(4.12)；Do not exist request to be distributed otherwise in scheduler, terminate this request distribution procedure；
(4.11) judge that next_rq [read] whether there is.If in the presence of jumping to step (4.13)；It is no
Then jump to step (4.14)；
(4.12) the batch processing stage of write request is ready for, write request is set to 0 by hungry number of times.
Whether the write request or next_rq [write] for then judging whether time-out are empty.If it is determined that result
It is true, jumps to step (4.15)；No person jumps to step (4.16)；
(4.13) request Drq to be distributed is set to next_rq [read], batching=0 is set, started
A reading batch phase is created, step (4.7) is jumped to；
(4.14) request Drq to be distributed is set to first request in scheduler reading chained list, is set
Batching=0, starts to create a reading batch phase, jumps to step (4.7)；
(4.15) request Drq to be distributed is set to scheduler and writes first in chained list request, set
Batching=0, starts establishment one and writes batch phase, jumps to step (4.8)；
(4.16) request Drq to be distributed is set to next_rq [write], batching=0 is set,
Start establishment one and write batch phase, jump to step (4.8).
As it will be easily appreciated by one skilled in the art that presently preferred embodiments of the present invention is the foregoing is only,
It is not intended to limit the invention, all any modifications made within the spirit and principles in the present invention, etc.
With replacement and improvement etc., should be included within the scope of the present invention.
Claims (4)
1. a kind of I O scheduling method based on solid-state disk read write attribute, it is characterised in that including following step
Suddenly：
(1) receive from upper layer application and by the bio requests after file system treatment, and judge the bio
The type of request is read request or write request, if read request is then transferred to step (2), if
Write request is then transferred to step (3)；
(2) judge the read request whether can read request adjacent thereto merge, if can not merge,
Then directly it is transferred to step (4)；If the size after can merging and merging is no more than the size of the page that clusters,
Then it is merged with neighbouring read request, the read request after merging still can be with reading adjacent thereto
Request is merged, and should be ensured that the size after merging is no more than the size of the page that clusters.Will be final
Read request after merging is put into reading queue and reading RBTree, so that system reads data.Then it is transferred to
Step (4).
(3) judge whether the write request can merge with the write request in caching, if can if
Merge, and by the write request insertion dispatcher queue end after merging, and it is transferred to step (4)；
Otherwise judge that can it merge with the write request in Hash table, if can if merge, and
Write request insertion dispatcher queue end after just merging, and it is transferred to step (4)；
(4) request in dispatcher queue is distributed in the request queue of device driver.
2. I O scheduling method according to claim 1, it is characterised in that step (2) including with
Lower sub-step：
(2.1) for the read request, the read request of last time merging is judged whether, if in the presence of,
Jump to step (2.2)；Otherwise jump to step (2.3)；
(2.2) judge the read request merged with last time after read request can merge.If can not
Merge, then jump to step (2.3), if preceding step (2.4) can be jumped to merging, if
Can backward merge, then jump to step (2.5)；
(2.3) judge that can the read request be merged backward with the request in ltsh chain table, if energy
Then jump to step (2.5)；Otherwise jump to step (2.6)；
(2.4) complete can the forward direction read request Rfrq and the read request that merge merge, and judge it is preceding to
Can the read request Rfrq after merging continue and read to be visited according to the starting of request in RBTree in scheduler
Ask the previous read request Rprev of the Rfrq of address sort before proceeding to merging.Step can then be jumped to
Suddenly (2.7), step (2.8) is otherwise jumped to；
(2.5) merging for the request Rbrq that can merge backward and the read request is completed, and judges conjunction backward
And can request Rbrq afterwards continue and the initial access in reading RBTree in scheduler according to request
The latter request Rnext of the Rbrq of location sequence proceeds backward merging.Step can then be jumped to
(2.9) step (2.10), is otherwise jumped to；
(2.6) to merging before judging the read request and being carried out with the request read in scheduler in RBTree,
If can if jump to step (2.4), otherwise jump to step (2.11)；
(2.7) read request Rfrq is completed to merge with the forward direction of read request Rperv, deletion scheduler reading queue,
Read the Rfrq requests in RBTree and generic block layer ltsh chain table；Simultaneously according to the read request being merged
Size changes positions of the Rprev in ltsh chain table；And by merging after service time the latest be set to
Less one in the service time the latest of Rfrq and Rprev；The read request mark that finally last time was merged
It is Rfrq.
(2.8) read request that last time merges is set to Rfrq, and updates Rfrq's in RBTree is read
Initial address；
(2.9) complete request Rbrq to merge with request the backward of Rnext, reading queue, reading in scheduler
Rnext requests are deleted in the ltsh chain table of RBTree and generic block layer, Rbrq requests is updated in hash chain
Position in table, by service time is set to the clothes of the read request after merging earlier in Rbrq and Rnext
The business time, the read request that Rbrq was merged labeled as last time, and jump to step (2.14)；
(2.10) read request for merging Rbrq labeled as last time, and Rbrq requests are updated in ltsh chain table
In position, terminate conversion；
(2.11) it is one request Rnrq of bio requests distribution, and initialization Rnrq is asked with the bio,
And judge whether Rnrq has merging attribute, if then jumping to step (2.12)；Otherwise jump to
Step (2.13)；
(2.12) Rnrq requests are added into ltsh chain table, and judges whether the read request of last time merging.
If it is present jumping directly to step (2.13)；The reading for otherwise first merging Rnrq labeled as last time
Request, and jump to step (2.13)；
(2.13) will Rnrq request add scheduler in read queue end and read RBTree in.
3. I O scheduling method according to claim 2, it is characterised in that step (3) including with
Lower sub-step：
(3.1) for the write request, the write request of last time merging is judged whether, if it does,
Jump to step (3.2)；Otherwise jump to step (3.3)；
(3.2) judge whether the write request that can merge with last time is merged for bio requests, if energy
To merging before enough, step (3.4) is jumped to；If can be merged backward, step (3.5) is jumped to；
If can not merge that step (3.3) is jumped to；
(3.3) judge that can bio requests be merged backward with the request in ltsh chain table, if energy
Then jump to step (3.5)；Otherwise jump to step (3.6)；
(3.4) to merging before the write request that bio requests merged with last time is carried out, and merging is judged
Can also continue afterwards with chained list is write in scheduler in its previous request Wprev proceed to merge.If
Can merge with Wprev, then jump to step (3.7), otherwise jump to step (3.8)；
(3.5) the backward merging of bio requests and the request Wbrq that can merge backward is completed, and judges to merge
Next request Wnext that can Wbrq afterwards write Wbrq in chained list with scheduler proceeds to close
And.Step (3.9) can then be jumped to；Otherwise jump to step (3.10)；
(3.6) it is one new request Wnrq of bio requests distribution, and initialization Wnrq is asked with the bio.
Then judge whether Wnrq has and merge attribute.Have, jump to step (3.11)；Otherwise jump to step
Suddenly (3.12)；
(3.7) complete merging for Wfrq and Wprev, and chained list, ltsh chain table are write in scheduler
Wfrq is deleted, then needs to adjust positions of the Wprev in ltsh chain table, be finally labeled as Wprev
The write request that last time merges, terminates this conversion by bio request conversions for write request；
(3.8) write request for merging Wfrq labeled as last time, by bio request conversions in order to write
Request, terminates this conversion；
(3.9) complete merging for Wbrq and Wnext, and write chained list, ltsh chain table in scheduler is deleted
Except Wnext, then need to adjust positions of the Wbrq in ltsh chain table, finally by Wbrq labeled as upper
The write request of secondary merging, terminates this conversion by bio request conversions for write request；
(3.10) positions of the adjustment Wbrq in ltsh chain table, and by Wbrq labeled as last time merging
Write request, terminates this conversion by bio request conversions for write request；
(3.11) by Wnrq add ltsh chain table in, and judge last time merge write request whether there is.
If not existing, the write request that Wnrq was merged labeled as last time, and jump to step (3.12)；It is no
Then, step (3.12) is leapt to；
(3.12) Wnrq addition schedulers are write into the afterbody of chained list, so as to by the bio ask conversion in order to
Write request.
4. I O scheduling method according to claim 3, it is characterised in that step (4) including with
Lower sub-step：
(4.1) judge that the stage distributed at present residing for request in dispatcher queue is in reading batch processing rank
Section still writes batch phase, if in batch phase is read, jumping to step (4.2)；If
In batch phase is write, then step (4.3) is jumped to,
(4.2) judge whether the request sum for reading batch phase distribution has exceeded threshold value.If having exceeded
Threshold value, then jump to step (4.4), otherwise jumps to step (4.5)；
(4.3) judge whether the request sum for writing batch phase distribution has reached the upper limit, if having reached the upper limit,
Step (4.4) is jumped to, step (4.6) is otherwise jumped to；
(4.4) batch phase is created, and determines to whether there is corresponding reading in dispatcher queue
Request, if in the presence of jumping to step (4.9)；Otherwise jump to step (4.10)；
(4.5) request Drq to be distributed in scheduler is set to next_rq [read], and jumps to step
Suddenly (4.7)；
(4.6) request Drq to be distributed in scheduler is set to next_rq [write], and jumps to step
Suddenly (4.8)；
(4.7) Drq is distributed in the request queue of device drive layer, from the reading chained list of scheduler and reading
Delete the Drq in RBTree, and next_rq [read] is set to Drq and read RBTree in scheduler
Next request, finally counts to the operation, terminates this request distribution procedure；
(4.8) Drq is distributed in the request queue of device drive layer, from scheduler write chained list in delete
Except Drq, it is next requests of the Drq in scheduler writes chained list to set next_rq [write], finally to this
Operation is counted, and terminates this request distribution procedure；
(4.9) writing with the presence or absence of request in chained list, if it does not exist, then jumping to for scheduler is judged
Step (4.11)；If it is present continuing to determine whether the write request or write request quilt that there is time-out
Hungry number of times has reached the upper limit, if it is decided that result is true, then jump to step (4.12)；Otherwise jump
Go to step (4.11)；
(4.10) writing with the presence or absence of request in chained list for scheduler is judged, if in the presence of jumping to step
(4.12)；Do not exist request to be distributed otherwise in scheduler, terminate this request distribution procedure；
(4.11) judge that next_rq [read] whether there is.If in the presence of jumping to step (4.13)；It is no
Then jump to step (4.14)；
(4.12) write request is set to 0 by hungry number of times.Then the write request of time-out is judged whether
Or whether next_rq [write] is empty.If it is determined that result is true, step (4.15) is jumped to；It is no
Person jumps to step (4.16)；
(4.13) request Drq to be distributed is set to next_rq [read], batching=0 is set, started
A reading batch phase is created, step (4.7) is jumped to；
(4.14) request Drq to be distributed is set to first request in scheduler reading chained list, is set
Batching=0, starts to create a reading batch phase, jumps to step (4.7)；
(4.15) request Drq to be distributed is set to scheduler and writes first in chained list request, set
Batching=0, starts establishment one and writes batch phase, jumps to step (4.8)；
(4.16) request Drq to be distributed is set to next_rq [write], batching=0 is set,
Start establishment one and write batch phase, jump to step (4.8).
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