JP4170506B2

JP4170506B2 - Arbitration circuit and method

Info

Publication number: JP4170506B2
Application number: JP08230099A
Authority: JP
Inventors: 雅浩星
Original assignee: Asahi Kasei EMD Corp
Current assignee: Asahi Kasei Microdevices Corp
Priority date: 1999-03-25
Filing date: 1999-03-25
Publication date: 2008-10-22
Anticipated expiration: 2019-03-25
Also published as: JP2000276440A

Description

【０００１】
【発明の属する技術分野】
本発明は、共有資源、たとえば、メモリを複数のＣＰＵや他の使用デバイスからの使用要求を調停する調停装置およびその方法に関する。
【０００２】
【従来の技術】
従来、バス接続されたメモリに対して複数のデバイスが同時にアクセスしようとした場合に、使用を許可するデバイスを調停回路により決定する。
【０００３】
そこで、本発明の目的は、要求を放棄する場合であっても調停時に共有資源の使用権を得ることができなかったデバイスが優先的に使用権を得ることができる調停装置およびその方法を提供することにある。
【０００４】
【発明が解決しようとする課題】
しかしながら上記提案では共有資源が許可される使用要求が許可信号を得られるまでなされる場合にはあまり問題がないものの、要求信号を途中で放棄する場合には公平性が極端に低下する。また乱数器を使用する場合でも使用要求がランダムであるので、長期的に見れば共有資源の使用許可を受けることができる確率は複数のデバイスでは均一になる。しかしながら短期的にみると、ある特定のデバイスの確率が高くなってしまう。
【０００５】
そこで、本発明の目的は、要求を放棄する場合であっても調停時に共有資源の使用権を得ることができなかったデバイスが優先的に使用権を得ることができる調停回路および方法を提供することにある。
【０００６】
【課題を解決するための手段】
このような目的を達成するために、請求項１の発明は、複数のデバイスにより資源を共有するシステムにおいて、前記複数のデバイスから前記資源に対する使用要求が同時に送られてきた場合に、デバイスについてあらかじめ定めた優先順位に従って、使用要求を送った複数のデバイスの中の最優先のデバイスに前記資源の使用権を与える調停装置あって、
前記複数のデバイスと同数の複数のアービタであって、当該複数のアービタの各々は前記複数のデバイスの各々と対応付けられていて、自己に対して割り当てられているデバイスに対してあらかじめ定めた調停条件に従って前記資源の使用権を与える複数のアービタ（２−１〜２−４）を有し、
前記あらかじめ定めた調停条件は、自己のアービタに割り当てられたデバイスが前記使用権を得た場合、そのときに同時に発生した他のデバイスの前記資源に対する使用要求の発生個数に応じてあらかじめ定められた回数だけ、以後、自己のアービタに割り当てられたデバイスに対する使用権を放棄し、使用権を放棄していない場合には、自己のアービタに割り当てられたデバイスの優先順位がもっとも高い場合に自己のアービタに割り当てられたデバイスに前記資源の使用権を与えるという条件であり、前記複数のアービタの各々は、
前記使用権を放棄していない場合かつ前記使用権が得られなかった場合に次回の前記資源の使用権を他のアービタに対して主張するための優先権要求情報を生成し保持し、前記資源の使用権を放棄している間は使用権の放棄を示す情報を生成し保持する優先権要求情報生成保持手段（１１、１２）と、
前記共有資源に対する前記複数のデバイスの使用要求が発生するごとに、前記他のアービタから今回の調停のための優先権要求情報を受け取り、
自己のアービタが前記資源の使用権を放棄している場合には、自己のアービタに割り当てられたデバイスには前記資源の使用権を与えない、
自己のアービタの優先権要求情報生成保持手段が優先権要求情報を生成している場合で、自己のアービタに割り当てられたデバイスの優先順位が最も高い場合には自己のアービタに割り当てられたデバイスに前記資源の使用権を与え、
自己のアービタの優先権要求情報生成保持手段が優先権要求情報を生成している場合で、自己のアービタに割り当てられたデバイスの優先順位よりも、優先権要求情報を生成した他のアービタのデバイスの優先順が高い場合には、自己のアービタに割り当てられたデバイスに前記使用権を与えない
の判定を行う調停判定手段（１３、１４）とを
有し、
使用権を与えるの判定を行った調停判定手段のアービタから該アービタに割り当てられたデバイスに対して前記資源の使用許可を与えることを特徴とする。
【０００７】
請求項２の発明は、請求項１に記載の調停装置において、前記優先権要求情報生成保持手段はシフトレジスタを有し、自己のアービタが前記資源の使用権を得た場合には、そのときに同時に発生した他のデバイスの前記資源に対する使用要求の発生個数に応じてあらかじめ定められた個数だけ、使用権の放棄を示すデータを前記シフトレジスタに記憶し、以後、調停が発生するごとに前記シフトレジスタに記憶されたデータをシフトすることにより、自己のアービタが使用権を放棄していることを前記自己のアービタの調停判定手段に伝えることを特徴とする。
【０００８】
請求項３の発明は、請求項２に記載の調停装置において、自己のアービタが前記資源の使用権を得た場合には、前記使用権の放棄を示すデータに引き続き優先権要求情報を前記シフトレジスタに記憶し、自己のアービタが前記資源の使用権を得られなかった場合には前記シフトレジスタに記憶されているデータをシフトし、前記優先権要求情報をこれまでの記憶データに引き続いてシフトレジスタに記憶することを特徴とすることを特徴とする。
【０００９】
請求項４の発明は、請求項３に記載の調停装置において、前記シフトレジスタの最後尾の記憶領域には、１つ前の記憶領域に記憶されているデータの値と自己のアービタに対応付けられている資源からの使用要求の有無との論理計算結果を記憶することにより、これまでに優先権要求を発生していても今回、自己のアービタに対応付けられている資源からの使用要求がない場合には優先権要求情報生成保持手段が優先権要求情報を生成しないようにしたことを特徴とする。
【００１０】
請求項５の発明は、複数のデバイスにより資源を共有するシステムにおいて、前記複数のデバイスから前記資源に対する使用要求が同時に送られてきた場合に、デバイスについてあらかじめ定めた優先順位に従って、使用要求を送った複数のデバイスの中の最優先のデバイスに前記資源の使用権を与える調停装置の調停方法あって、前記調停装置は、
前記複数のデバイスと同数の複数のアービタであって、当該複数のアービタの各々は前記複数のデバイスの各々と対応付けられていて、自己に対して割り当てられているデバイスに対してあらかじめ定めた調停条件に従って前記資源の使用権を与える複数のアービタ（２−１〜２−４）を有し、
前記あらかじめ定めた調停条件は、自己のアービタに割り当てられたデバイスが前記使用権を得た場合、そのときに同時に発生した他のデバイスの前記資源に対する使用要求の発生個数に応じてあらかじめ定められた回数だけ、以後、自己のアービタに割り当てられたデバイスに対する使用権を放棄し、使用権を放棄していない場合には、自己のアービタに割り当てられたデバイスの優先順位がもっとも高い場合に自己のアービタに割り当てられたデバイスに前記資源の使用権を与えるという条件であり、
前記複数のアービタの各々は、優先権要求情報生成保持手段（１１、１２）および調停判定手段（１３、１４）を有し、
前記優先権要求情報生成保持手段により、前記使用権を放棄していない場合かつ前記使用権が得られなかった場合に次回の前記資源の使用権を他のアービタに対して主張するための優先権要求情報を生成し保持し、前記資源の使用権を放棄している間は使用権の放棄を示す情報を生成し保持し、
前記共有資源に対する前記複数のデバイスの使用要求が発生するごとに、前記他のアービタから今回の調停のための優先権要求情報を受け取り、
自己のアービタが前記資源の使用権を放棄している場合には、自己のアービタに割り当てられたデバイスには前記資源の使用権を与えない、
自己のアービタの優先権要求情報生成保持手段が優先権要求情報を生成している場合で、自己のアービタに割り当てられたデバイスの優先順位が最も高い場合には自己のアービタに割り当てられたデバイスに前記資源の使用権を与え、
自己のアービタの優先権要求情報生成保持手段が優先権要求情報を生成している場合で、自己のアービタに割り当てられたデバイスの優先順位よりも、優先権要求情報を生成した他のアービタのデバイスの優先順が高い場合には、自己のアービタに割り当てられたデバイスに前記使用権を与えない
の判定を前記調停判定手段により行い、
使用権を与えるの判定を行った調停判定手段のアービタから該アービタに割り当てられたデバイスに対して前記資源の使用許可を与えることを特徴とする。
【００１１】
請求項６の発明は、請求項５に記載の調停装置の調停方法において、前記優先権要求情報生成保持手段はシフトレジスタを有し、自己のアービタが前記資源の使用権を得た場合には、そのときに同時に発生した他のデバイスの前記資源に対する使用要求の発生個数に応じてあらかじめ定められた個数だけ、使用権の放棄を示すデータを前記シフトレジスタに記憶し、以後、調停が発生するごとに前記シフトレジスタに記憶されたデータをシフトすることにより、自己のアービタが使用権を放棄していることを前記自己のアービタの調停判定手段に伝えることを特徴とする。
【００１２】
請求項７の発明は、請求項６に記載の調停装置の調停方法において、自己のアービタが前記資源の使用権を得た場合には、前記使用権の放棄を示すデータに引き続き優先権要求情報を前記シフトレジスタに記憶し、以後調停が発生し自己のアービタが前記資源の使用権を得られなかった場合には前記シフトレジスタに記憶されているデータをシフトし、前記優先権要求情報をこれまでの記憶データに引き続いてシフトレジスタに記憶することを特徴とすることを特徴とする。
請求項８の発明は、請求項７に記載の調停装置の調停方法において、前記シフトレジスタの最後尾の記憶領域には、１つ前の記憶領域に記憶されているデータの値と自己のアービタに対応付けられている資源からの使用要求の有無との論理計算結果を記憶することにより、これまでに優先権要求を発生していても今回、自己のアービタに対応付けられている資源からの使用要求がない場合には優先権要求情報生成保持手段が優先権要求情報を生成しないようにしたことを特徴とする。
【００１３】
【発明の実施の形態】
以下、図面を参照して本発明の実施形態を詳細に説明する。図１は本発明を適用した調停装置（回路）の回路構成を示す。
【００１４】
図１において、０Ａ，０Ｂ，０Ｃ，０Ｄは共有資源１に対する使用を要求する使用要求信号をそれぞれ転送する信号線である。２−１〜２−４は上記４つの信号線に対応する個数だけ設けられるアービタである。たとえばアービタＡは信号線０Ａから転送される使用要求信号と対応付けられ、この信号線の使用要求信号に対して共有資源の使用許可が与えられたときに、信号線００Ａを介して、調停結果を示す信号を共有資源１に出力する。他のアービタＢ〜ＤもアービタＡと同様の機能を有する。
【００１５】
調停要求回路５は調停装置２に対して調停の実行を指示する。調停要求回路５の構成の一例を図２に示す。この回路例では、不図示のタイマーによりバーストサイクル等の最大アクセス時間の終了が検知されたとき、アクセス権のある信号線（チャンネル）の使用要求解除があったとき、共有資源１のアクセス状態に応じて、上記各状態を示す信号を調停要求信号０ＳとしてアービタＡ〜Ｄに出力する。
【００１６】
このような機能を持つアービタ２の構成をアービタＡを例にして説明する。図３はアービタＡ（他も同様）を回路構成を示す。
【００１７】
図３において、優先要求情報生成回路１１は表１の生成条件に従って信号線Ａについての優先要求情報を生成する。
【００１８】
【表１】

【００１９】
優先権要求情報には、＄Ａ［０］〜＄［３］の４種類がある。信号線０Ａ〜０Ｄに使用要求信号が発生し、信号線０Ａに対して共有資源の使用権が与えられたときに、使用要求信号の発生個数に応じて、＄Ａ［０］〜＄Ａ［３］の値が定められる。他の信号線（０Ｂ〜０Ｄ）上に１以上使用要求があるとき＄Ａ［０］の値が“０”（優先権要求放棄）の値に設定される。
【００２０】
２以上の使用要求があるときは＄Ａ［１］の値が“０”に設定される。３以上の使用要求があるときは＄Ａ［２］の値が“０”に設けられる。＄Ａ［３］は優先権要求を示す“１”を設定する。
【００２１】
優先要求情報保持回路１２はシフトレジスタで構成され、上述の値を図３に示す位置のレジスタに保持する。また調停要求信号０Ｓが発生する毎に保持する値をシフトする。この値のシフトによって、自己の信号線（この場合、０Ａ）では１度使用権を得た後、同時発生の使用要求信号の個数に応じた調停回数だけ優先要求情報（ビット“１”）の発生が停止される（優先権を放棄）。
【００２２】
調停判定回路１３は信号線０Ａ，０ＢＢ，０ＣＣ，０ＤＤからの信号と、優先要求情報保持回路１２からの信号を入力し、信号線Ａについての使用権の授与／不授与を表２および表３の判定条件に従って決定する。その決定結果に応じて、アクセス信号保持回路１４が００Ａ信号により共有資源１をアクセス可能とする。
【００２３】
【表２】

【００２４】
【表３】

【００２５】
表２は信号線Ａについて優先要求および使用要求の信号に基き、アービタＡから他のアービタＢ〜Ｄに出力する優先要求信号０ＡＡのビット値を決定するための条件を示す。
【００２６】
表３は各アービタ間で転送される優先要求信号のビット値と、共有資源１の使用許可を与える信号線との関係を示す。
【００２７】
以下、図４および図５を参照して図１の調停装置の調停動作を説明する。図４および図５は信号線０Ａ〜０Ｄ上の使用要求信号の時間的な変化の状態と、各アービタの優先要求情報保持回路１２で保持される値との対応関係を示す。
【００２８】
時刻Ｔ１で信号線０Ａ〜０Ｄ上に使用要求が出力されていない場合、これらの信号線上のビット値は全て“０”となる。また、各アービタの優先要求情報保持回路１２で保持される＄Ａ（３）〜＄Ａ（０），＄Ｂ（３）〜＄Ｂ（０）・・・の値はデフォルト値“１”が設定される。
【００２９】
調停要求回路５からの調停要求信号０ＳがタイミングＴ２で発生すると、各アービタは信号線０Ａ〜０Ｄ上の使用要求信号を優先要求情報生成回路１１に入力する。
【００３０】
また、アービタＡの調停判定回路１３は信号線０Ａ上の使用要求信号を入力し、アービタＢの調停判定回路１３は信号線０Ｂ上の使用要求信号というように各調停判定回路１３は自己に割当てられた使用要求信号を入力する。
【００３１】
時刻Ｔ２では図４に示すように、保持されている＄Ａ（０）の値が“１”であるので、アービタＡの調停判定回路１３は表２の調停判定条件に従って、優先要求信号０ＡＡをビットをビット“１”に設定する。
【００３２】
アービタＢ，Ｃ，Ｄでは優先要求信号０ＢＢ〜０ＤＤをビット“１”に設定する。これらの優先要求信号の値が設定されると、各アービタの調停判定回路１３では表３のアクセス決定条件に従って共有資源１に使用権を与えるアービタを決定する。
【００３３】
表３の条件ではアービタＡ，Ｂ，Ｃ，Ｄの順位で優先順位が定められている。このため、アービタＡについての０ＡＡの優先要求信号が“１”の場合には他のアービタの優先要求信号の値にかかわらず、アービタＡに共有資源１に対する使用権が与えられ、アービタＡのアクセス信号００Ａがビット“１”となり、信号線０Ａの使用要求信号を発生したデバイスが共有資源１を使用することが可能となる。
【００３４】
一方、他のアービタＢ〜Ｄでは表３の条件に従って、アクセス信号を“０”に設定するので、信号線０Ｂ〜０Ｄ上の使用要求信号を発生したデバイスは共有資源１を使用することができない。
【００３５】
この時点（Ｔ２）でアービタＡが共有資源１の使用権を取得する。使用権が与えられなかった他のアービタが受け持つ使用要求信号の個数は“３”であるので、アービタＡの優先情報保持回路１２が保持する値は、表１に従って決定され、＄Ａ[３]＝１、＄Ａ[２]＝０、＄Ａ[１]＝０、＄Ａ[０]＝０（図４の時刻Ｔ２のアービタＡ，次回データを参照）
【００３６】
アービタＢ〜Ｄでは時刻Ｔ２で使用権要求信号が発生したにもかかわらず、共有資源１の使用権が与えられなかったので、表１の「アクセス権を得られぬアービタＢ等」の条件に従って、たとえば、アービタＢでは＄[３]の値を＄Ｂ[２]にシフトし、＄Ｂ[２]の値を＄Ｂ[１]にシフトする。また、＄Ｂ[０]には＄Ｂ[１]と信号ＯＢの論理値が保持される。
【００３７】
このようにして、アービタＢ〜Ｄでは＄［３］〜＄［０］が決定される。この例ではアービタＢ〜Ｄの＄［０］の値は“１”となる（図４参照）。
【００３８】
次の調停時刻Ｔ３において、図４に示すような使用要求信号が発生したとする。この例では、信号線０Ａ，０Ｂ，０Ｄが使用要求発生、信号線０Ｃが使用放棄となっている。
【００３９】
この時刻Ｔ３で各アービタの調停判定回路１３は、自己の＄［０］の値と、自己の担当する今回の使用要求信号の値に基き、表２の条件に従って、優先要求信号０ＡＡ〜０ＤＤの値を決定する。前回、共有資源１の使用権を取得したアービタＡでは＄Ａ［０］の値が“０”であるので、優先要求信号の値は“０”（優先要求無し）となる。
【００４０】
アービタＢでは＄Ｂ［０］の値が“１”（図４参照）であり、前回に引き続き、今回も使用要求が発生しているので、優先要求信号０ＢＢの値は“１”となる。アービタＣでは今回の使用要求が発生していないので、表２の条件に従って優先要求信号０ＣＣの値は“０”となる。
【００４１】
アービタＤはアービタＢと同じ条件が適用され、優先要求信号０ＤＤの値は“１”となる。
【００４２】
この結果、アービタＡは前回共有資源１の使用権を得たので、今回は使用権放棄となり、アービタＢとＤが優先要求権を持つことになる。
【００４３】
複数の優先要求権が同時に発生した場合、表３に従って調停が行なわれる。この例ではアービタＢが優先順位が高いので、アービタＢに対して共有資源１の使用権が与えられる。
【００４４】
なお、本形態では所定回数は同時発生の使用要求信号の個数に応じて定まるがこの点は後述する。
【００４５】
連続して同一信号線上の使用要求信号を受付け、共有資源１の使用権が得られなかったアービタＢ，Ｄは次回に調停時には、使用要求を入力し、優先権のない他のアービタＡよりも共有資源１の使用要求に対して優先権を持つ。さらに、優先要求権を持つ複数のアービタＡ〜Ｄが発生した場合は、予め定めたアービタの優先順位に従って、優先要求権を与えるアービタを決定する。
【００４６】
次に、時刻Ｔ２で共有資源１の使用権を取得したアービタＡの以後の動作を説明する。時刻Ｔ２で共有資源１の使用権を取得したときに、アービタＡ内の優先要求信号の＄Ａ［２］〜＄Ａ［０］はビット“０”に設定される（図４参照）。
【００４７】
この時点で使用要求が発生した個数は自己を入れて４つであったので、他３つのアービタに優先要求権を譲るために＄Ａ［２］〜＄Ａ［０］の３つのデータが選択される。たとえば使用要求が発生した個数が自己を入れて２の場合には＄Ａ［０］にビット“０”が設定される。
【００４８】
このように＄Ａ［０］〜＄Ａ［２］にビット“０”を設定すると、次の時刻Ｔ３では、表２の判定条件によりアービタＡには優先要求権が与えられない。
【００４９】
以下、＄Ａの値は図４，図５に示すように順次に［３］から［０］に向ってシフトされるので、時刻Ｔ３，Ｔ４，Ｔ５の３回はアービタＡは優先要求権を得ることはできず、時刻Ｔ６で優先要求権を得ることができる。
【００５０】
以上、説明したように、一度、共有資源１の使用権を取得したアービタＡは、その時点で発生した他の使用要求（３つ）のために調停回数において３回優先要求権を放棄するので、他のアービタでは、以後、連続的に使用要求を受けつけている限りは、３回以内に必ず共有資源１の使用権を得ることができる。
【００５１】
上述の実施形態の他に次の形態を実施できる。
【００５２】
１）上述の実施形態では４つのチャンネル（信号線）についての調停装置を説明したがこの個数に限定する必要はない。
【００５３】
２）共通資源１はメモリを例としたがメモリに限らず、共有バス等他のデバイスにも本発明を適用できる。
【００５４】
【発明の効果】
以上、説明したように、請求項１，５の発明によれば、共有資源の使用権を、取得したかどうかで動的に優先要求情報を更新するので、その間に、使用権が得られなかった使用要求で、優先権を持つ使用要求が必ず共有資源の使用権を得ることができ、使用権を得る確率が均等となり、かつ、使用権が得られない場合にも一定期間内に必ず使用権を取得することが可能となる。
【００５５】
請求項２，６の発明によれば、使用権を得たかの情報がより細やかになり、さらに公平性が向上する。
【００５６】
請求項３，７の発明では、優先権を持つ使用要求が複数存在する場合には予め定めた優先順により使用権が与えられる。この場合でも、使用権が与えられると、その使用要求に対しては以後、優先権が放棄されるので、使用権が得られず、優先権を持つ使用要求が優先される。
【００５７】
請求項４の発明では、上記の制御が小規模の回路構成で達成できる。
【図面の簡単な説明】
【図１】本発明実施形態の回路構成を示す回路図である。
【図２】本発明実施形態の調停要求回路５の回路構成を示す回路図である。
【図３】本発明実施形態のアービタの構成を示す回路図である。
【図４】本発明実施形態の調停内容を示す説明図である。
【図５】本発明実施形態の調停内容を示す説明図である。
【符号の説明】
１共有資源
２アービタ
５調停要求回路
１１優先要求情報発生回路
１２優先要求情報保持回路
１３調停判定回路
１４アクセス信号保持回路[0001]
BACKGROUND OF THE INVENTION
The present invention, shared resources, for example, relates to arbitration device and method for arbitrating use request memory from a plurality of CPU or other device used.
[0002]
[Prior art]
Conventionally, when a plurality of devices attempt to access a bus-connected memory at the same time, a device to be used is determined by an arbitration circuit.
[0003]
An object of the present invention, provides an arbitration device and method that device could not get the right to use the shared resource during arbitration even if it is possible to obtain a preferential use right to abandon the request There is to do.
[0004]
[Problems to be solved by the invention]
However, in the above proposal, there is not much problem when a use request for permitting shared resources is made until a permission signal is obtained, but when the request signal is abandoned, the fairness is extremely lowered. Even when a random number device is used, since the usage request is random, the probability that the use permission of the shared resource can be obtained becomes uniform in a plurality of devices in the long term. However, in the short term, the probability of a particular device will increase.
[0005]
Therefore, an object of the present invention is to provide an arbitration circuit and method in which a device that has not been able to obtain a use right of a shared resource at the time of arbitration can preferentially obtain the use right even when the request is abandoned. There is.
[0006]
[Means for Solving the Problems]
In order to achieve such an object, the invention according to claim 1 is a system in which resources are shared by a plurality of devices, and when a use request for the resources is simultaneously sent from the plurality of devices, There is an arbitration device that grants the right to use the resource to the highest priority device among a plurality of devices that have sent a use request according to a predetermined priority order.
A plurality of arbiters equal in number to the plurality of devices, each of the plurality of arbiters being associated with each of the plurality of devices and pre-arbitrated for a device assigned to itself A plurality of arbiters (2-1 to 2-4) that give the right to use the resource according to conditions;
The predetermined arbitration condition is predetermined according to the number of use requests for the resources of other devices generated at the same time when the device assigned to the arbiter obtains the use right. After that, the right to use the device assigned to its own arbiter is relinquished, and if the right to use is not relinquished, the device assigned to its own arbiter has its highest priority. And granting the right to use the resource to the device assigned to each of the plurality of arbiters,
If the use right is not abandoned and the use right is not obtained, priority request information for asserting the next use right of the resource to another arbiter is generated and held, and the resource Priority request information generation / holding means (11, 12) for generating and holding information indicating the waiver of the usage right while the usage right is being abandoned;
Each time a request for using the plurality of devices for the shared resource occurs, priority request information for the current arbitration is received from the other arbiter,
If the arbiter has renounced the right to use the resource, the device assigned to the arbiter is not granted the right to use the resource;
When the priority request information generation / holding means of the own arbiter generates priority request information, and the device assigned to the own arbiter has the highest priority, it is assigned to the device assigned to the own arbiter. Give the right to use the resource,
When the priority request information generation / holding means of the own arbiter is generating the priority request information, the device of another arbiter that has generated the priority request information rather than the priority of the device assigned to the own arbiter If the priority of the device is high, the right to use is not granted to the device assigned to its arbiter.
Arbitration determination means (13, 14) for determining
Have
The arbiter of the arbitration determination unit that has determined whether to give the right to use grants permission to use the resource to the device assigned to the arbiter.
[0007]
According to a second aspect of the present invention, in the arbitration device according to the first aspect, the priority request information generation / holding means includes a shift register, and if the arbiter obtains the right to use the resource, In the shift register, data indicating abandonment of usage rights is stored in the shift register by a predetermined number according to the number of usage requests for the resources of other devices that are generated at the same time. By shifting the data stored in the shift register, the arbitration determining means of the own arbiter is informed that the own arbiter has abandoned the right to use.
[0008]
According to a third aspect of the present invention, in the arbitration device according to the second aspect, when the arbiter obtains the right to use the resource, the priority request information is shifted to the data indicating the waiver of the right to use. If the arbiter cannot obtain the right to use the resource, the data stored in the shift register is shifted, and the priority request information is shifted to the previous stored data. It is characterized in that it is stored in a register.
[0009]
According to a fourth aspect of the present invention, in the arbitration device according to the third aspect, the last storage area of the shift register is associated with the value of the data stored in the previous storage area and its own arbiter. By storing the logical calculation result of whether or not there is a use request from the resource that has been assigned, even if a priority request has been generated so far, the use request from the resource associated with its own arbiter If not, the priority request information generation / holding means does not generate priority request information.
[0010]
According to a fifth aspect of the present invention, in a system in which a resource is shared by a plurality of devices, when a use request for the resource is sent from the plurality of devices at the same time, the use request is sent according to a predetermined priority order for the device. There is an arbitration method of an arbitration device that gives the right to use the resource to the highest priority device among a plurality of devices, the arbitration device comprising:
A plurality of arbiters equal in number to the plurality of devices, each of the plurality of arbiters being associated with each of the plurality of devices and pre-arbitrated for a device assigned to itself A plurality of arbiters (2-1 to 2-4) that give the right to use the resource according to conditions;
The predetermined arbitration condition is predetermined according to the number of use requests for the resources of other devices generated at the same time when the device assigned to the arbiter obtains the use right. After that, the right to use the device assigned to its own arbiter is relinquished, and if the right to use is not relinquished, the device assigned to its own arbiter has its highest priority. And granting the right to use the resource to the device assigned to
Each of the plurality of arbiters has priority request information generation / holding means (11, 12) and arbitration determination means (13, 14),
The priority for asserting the next use right of the resource to another arbiter when the use right is not abandoned and the use right is not obtained by the priority request information generation / holding means. Generate and hold request information, and generate and hold information indicating waiver of the usage right while waiving the right to use the resource,
Each time a request for using the plurality of devices for the shared resource occurs, priority request information for the current arbitration is received from the other arbiter,
If the arbiter has renounced the right to use the resource, the device assigned to the arbiter is not granted the right to use the resource;
When the priority request information generation / holding means of the own arbiter generates priority request information, and the device assigned to the own arbiter has the highest priority, it is assigned to the device assigned to the own arbiter. Give the right to use the resource,
When the priority request information generation / holding means of the own arbiter is generating the priority request information, the device of another arbiter that has generated the priority request information rather than the priority of the device assigned to the own arbiter If the priority of the device is high, the right to use is not granted to the device assigned to its arbiter.
Is determined by the arbitration determination means,
The arbiter of the arbitration determination unit that has determined whether to give the right to use grants permission to use the resource to the device assigned to the arbiter.
[0011]
According to a sixth aspect of the present invention, in the arbitration method of the arbitration device according to the fifth aspect, the priority request information generation / holding means includes a shift register, and when the arbiter obtains the right to use the resource. A predetermined number of data indicating the abandonment of usage rights is stored in the shift register in accordance with the number of usage requests for the resources of other devices generated at the same time, and then arbitration occurs. By shifting the data stored in the shift register every time, the arbitration determination means of the own arbiter is informed that the own arbiter has abandoned the right to use.
[0012]
According to a seventh aspect of the present invention, in the arbitration method of the arbitration device according to the sixth aspect, when the arbiter obtains the right to use the resource, the priority request information continues following the data indicating the waiver of the right to use. Is stored in the shift register, and when arbitration occurs and the arbiter cannot obtain the right to use the resource, the data stored in the shift register is shifted, and the priority request information is transferred to the shift register. It is characterized in that it is stored in a shift register subsequent to the stored data up to.
According to an eighth aspect of the present invention, in the arbitration method of the arbitration device according to the seventh aspect, in the last storage area of the shift register, the value of data stored in the previous storage area and its own arbiter By storing the logical calculation result of whether or not there is a usage request from the resource associated with the resource, even if a priority request has been generated so far, the resource from the resource associated with its own arbiter It is characterized in that priority request information generation / holding means does not generate priority request information when there is no use request.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a circuit configuration of an arbitration device (circuit) to which the present invention is applied.
[0014]
In FIG. 1, reference numerals 0A, 0B, 0C, and 0D denote signal lines for transferring use request signals for requesting use of the shared resource 1, respectively. Reference numerals 2-1 to 2-4 denote arbiters provided in the number corresponding to the four signal lines. For example, the arbiter A is associated with the use request signal transferred from the signal line 0A, and when the use permission of the shared resource is given to the use request signal of the signal line, the arbitration result is transmitted through the signal line 00A. Is output to the shared resource 1. The other arbiters B to D have the same function as the arbiter A.
[0015]
The arbitration request circuit 5 instructs the arbitration device 2 to execute arbitration. An example of the configuration of the arbitration request circuit 5 is shown in FIG. In this circuit example, when the end of the maximum access time such as a burst cycle is detected by a timer (not shown), when the use request of a signal line (channel) with access right is released, the access state of the shared resource 1 is set. In response, signals indicating the above states are output to the arbiters A to D as the arbitration request signal 0S.
[0016]
The configuration of the arbiter 2 having such a function will be described by taking the arbiter A as an example. FIG. 3 shows a circuit configuration of the arbiter A (the same applies to others).
[0017]
In FIG. 3, the priority request information generation circuit 11 generates priority request information for the signal line A according to the generation conditions in Table 1.
[0018]
[Table 1]

[0019]
There are four types of priority request information, $ A [0] to $ [3]. When a use request signal is generated on the signal lines 0A to 0D and the use right of the shared resource is given to the signal line 0A, $ A [0] to $ A [ 3] is determined. When one or more use requests are made on other signal lines (0B to 0D), the value of $ A [0] is set to a value of “0” (priority request abandonment).
[0020]
When there are two or more usage requests, the value of $ A [1] is set to “0”. When there is a usage request of 3 or more, the value of $ A [2] is set to “0”. $ A [3] sets “1” indicating a priority request.
[0021]
The priority request information holding circuit 12 is composed of a shift register, and holds the above-described value in the register at the position shown in FIG. The held value is shifted every time the arbitration request signal 0S is generated. By shifting the value, after obtaining the right to use the signal line (0A in this case) once, the priority request information (bit “1”) is transferred by the number of arbitrations according to the number of simultaneous use request signals. Occurrence is stopped (priority is abandoned).
[0022]
The arbitration determination circuit 13 receives signals from the signal lines 0A, 0BB, 0CC, and 0DD and a signal from the priority request information holding circuit 12, and gives grant / non-grant of use rights for the signal line A in Tables 2 and 3 It is determined according to the determination conditions. According to the determination result, the access signal holding circuit 14 makes the shared resource 1 accessible by the 00A signal.
[0023]
[Table 2]

[0024]
[Table 3]

[0025]
Table 2 shows conditions for determining the bit value of the priority request signal 0AA output from the arbiter A to the other arbiters B to D based on the priority request and use request signals for the signal line A.
[0026]
Table 3 shows the relationship between the bit value of the priority request signal transferred between the arbiters and the signal line that gives permission to use the shared resource 1.
[0027]
Hereinafter, the arbitration operation of the arbitration device in FIG. 1 will be described with reference to FIGS. 4 and 5. 4 and 5 show the correspondence between the temporal change states of the use request signals on the signal lines 0A to 0D and the values held in the priority request information holding circuit 12 of each arbiter.
[0028]
When use requests are not output on the signal lines 0A to 0D at time T1, the bit values on these signal lines are all “0”. The values of $ A (3) to $ A (0), $ B (3) to $ B (0)... Held by the priority request information holding circuit 12 of each arbiter are the default value “1”. Is set.
[0029]
When the arbitration request signal 0S from the arbitration request circuit 5 is generated at the timing T2, each arbiter inputs a use request signal on the signal lines 0A to 0D to the priority request information generation circuit 11.
[0030]
Further, the arbitration determination circuit 13 of the arbiter A receives the use request signal on the signal line 0A, and the arbitration determination circuit 13 of the arbiter B assigns itself to the use request signal on the signal line 0B. The requested use request signal is input.
[0031]
At time T2, as shown in FIG. 4, since the value of $ A (0) held is “1”, the arbitration determination circuit 13 of the arbiter A outputs the priority request signal 0AA according to the arbitration determination conditions in Table 2. Set the bit to bit “1”.
[0032]
In the arbiters B, C, and D, the priority request signals 0BB to 0DD are set to the bit “1”. When the values of these priority request signals are set, the arbitration determination circuit 13 of each arbiter determines an arbiter that gives the usage right to the shared resource 1 according to the access determination conditions shown in Table 3.
[0033]
Under the conditions in Table 3, the priorities are determined in the order of arbiters A, B, C, and D. Therefore, when the priority request signal of 0AA for the arbiter A is “1”, the right to use the shared resource 1 is given to the arbiter A regardless of the value of the priority request signal of the other arbiter. The signal 00A becomes the bit “1”, and the device that has generated the use request signal for the signal line 0A can use the shared resource 1.
[0034]
On the other hand, in the other arbiters B to D, the access signal is set to “0” according to the conditions of Table 3, so that the device that has generated the use request signal on the signal lines 0 B to 0 D cannot use the shared resource 1. .
[0035]
Arbiter A is that Tokusu preparative use right of the shared resource 1 at this time (T 2). Since the number of use request signals handled by other arbiters to which usage rights have not been given is “3”, the value held by the priority information holding circuit 12 of the arbiter A is determined according to Table 1, and $ A [3] = 1, $ a [2] = 0, $ a [1] = 0, $ a [0] = 0 ( arbiter time T 2 of the FIG. 4 a, see next data)
[0036]
In arbiters B to D, the usage right request signal is generated at time T 2, but the usage right of the shared resource 1 is not given, so the conditions of “arbiter B etc. that cannot obtain the access right” in Table 1 Thus, for example, the arbiter B shifts the value of $ [3] to $ B [2] and shifts the value of $ B [2] to $ B [1]. $ B [0] holds the logical value of $ B [1] and the signal OB.
[0037]
In this way, arbiters B to D determine $ [3] to $ [0]. In this example, the value of $ [0] of the arbiters B to D is “1” (see FIG. 4).
[0038]
Assume that a use request signal as shown in FIG. 4 is generated at the next arbitration time T3. In this example, the signal lines 0A, 0B, and 0D are used, and the signal line 0C is abandoned.
[0039]
At this time T3, the arbitration determination circuit 13 of each arbiter determines the priority request signals 0AA to 0DD according to the conditions of Table 2 based on the value of its own $ [0] and the value of the current use request signal that it is responsible for. Determine the value. Since the value of $ A [0] is “0” in the arbiter A that acquired the right to use the shared resource 1 last time, the value of the priority request signal is “0” (no priority request).
[0040]
In the arbiter B, the value of $ B [0] is “1” (see FIG. 4), and since the use request is generated again this time, the value of the priority request signal 0BB is “1”. Since the current use request is not generated in the arbiter C, the value of the priority request signal 0CC is “0” according to the conditions in Table 2.
[0041]
Arbiter D has the same conditions as arbiter B, and the value of priority request signal 0DD is “1”.
[0042]
As a result, since the arbiter A has obtained the right to use the shared resource 1 last time, the use right is abandoned, and the arbiters B and D have the priority request right.
[0043]
When a plurality of priority request rights occur simultaneously, arbitration is performed according to Table 3. In this example, since the arbiter B has a high priority, the right to use the shared resource 1 is given to the arbiter B.
[0044]
In the present embodiment, the predetermined number of times is determined according to the number of simultaneous use request signals, which will be described later.
[0045]
The arbiters B and D that continuously receive use request signals on the same signal line and have not obtained the use right of the shared resource 1 will input the use request at the next arbitration, and more than other arbiters A without priority. Priority is given to the use request of the shared resource 1. Further, when a plurality of arbiters A to D having a priority request right are generated, an arbiter to which the priority request right is given is determined according to a predetermined priority order of the arbiter.
[0046]
Next, the subsequent operation of the arbiter A that acquired the right to use the shared resource 1 at time T2 will be described. When the right to use shared resource 1 is acquired at time T2, the priority request signals $ A [2] to $ A [0] in arbiter A are set to bit “0” (see FIG. 4).
[0047]
Since the number of use requests generated at this point is four including the self, three data of $ A [2] to $ A [0] are selected to give priority request right to the other three arbiters. Is done. For example, if the number of usage requests is 2, including itself, bit “0” is set in $ A [0].
[0048]
When the bit “0” is set in $ A [0] to $ A [2] as described above, the priority request right is not given to the arbiter A at the next time T3 due to the determination condition shown in Table 2.
[0049]
Since the value of $ A is sequentially shifted from [3] to [0] as shown in FIGS. 4 and 5, the arbiter A has the priority request right three times at times T3, T4 and T5. The priority request right can be obtained at time T6.
[0050]
As described above, the arbiter A that once acquired the right to use the shared resource 1 renounces the priority request right three times in the number of arbitrations for the other use requests (three) that occurred at that time. In other arbiters, the right to use the shared resource 1 can always be obtained within three times as long as requests for use are continuously received.
[0051]
In addition to the above embodiment, the following embodiment can be implemented.
[0052]
1) In the above-described embodiment, the arbitration device for four channels (signal lines) has been described. However, the number of arbitration devices is not limited to this number.
[0053]
2) The common resource 1 is a memory. However, the present invention is not limited to the memory and can be applied to other devices such as a shared bus.
[0054]
【The invention's effect】
As described above, according to the first and fifth aspects of the invention, the priority request information is dynamically updated depending on whether or not the right to use the shared resource has been acquired. The use request with priority can always obtain the right to use the shared resource, the probability of obtaining the use right is equal, and even if the right to use cannot be obtained, it must be used within a certain period of time. The right can be acquired.
[0055]
According to the second and sixth aspects of the invention, the information on whether or not the right to use is obtained becomes more detailed, and the fairness is further improved.
[0056]
According to the third and seventh aspects of the present invention, when there are a plurality of usage requests having priority, the usage right is given in a predetermined priority order. Even in this case, if the right to use is given, the right to use is subsequently abandoned, so that the right to use cannot be obtained, and the use request with priority is given priority.
[0057]
In the invention of claim 4, the above control can be achieved with a small circuit configuration.
[Brief description of the drawings]
FIG. 1 is a circuit diagram showing a circuit configuration of an embodiment of the present invention.
FIG. 2 is a circuit diagram showing a circuit configuration of an arbitration request circuit 5 according to an embodiment of the present invention.
FIG. 3 is a circuit diagram showing a configuration of an arbiter according to an embodiment of the present invention.
FIG. 4 is an explanatory diagram showing details of mediation according to an embodiment of the present invention.
FIG. 5 is an explanatory diagram showing details of arbitration according to an embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shared resource 2 Arbiter 5 Arbitration request circuit 11 Priority request information generation circuit 12 Priority request information holding circuit 13 Arbitration determination circuit 14 Access signal holding circuit

Claims

In a system in which resources are shared by a plurality of devices, when use requests for the resources are sent from the plurality of devices at the same time, among the plurality of devices that have sent the use requests according to a predetermined priority order for the devices. There is an arbitration device that gives the highest priority device the right to use the resource,
A plurality of arbiters equal in number to the plurality of devices, each of the plurality of arbiters being associated with each of the plurality of devices and pre-arbitrated for a device assigned to itself A plurality of arbiters (2-1 to 2-4) that give the right to use the resource according to conditions;
The predetermined arbitration condition is predetermined according to the number of use requests for the resources of other devices generated at the same time when the device assigned to the arbiter obtains the use right. After that, the right to use the device assigned to its own arbiter is relinquished, and if the right to use is not relinquished, the device assigned to its own arbiter has its highest priority. And granting the right to use the resource to the device assigned to each of the plurality of arbiters,
If the use right is not abandoned and the use right is not obtained, priority request information for asserting the next use right of the resource to another arbiter is generated and held, and the resource Priority request information generation / holding means (11, 12) for generating and holding information indicating the waiver of the usage right while the usage right is being abandoned;
Each time a request for using the plurality of devices for the shared resource occurs, priority request information for the current arbitration is received from the other arbiter,
If the arbiter has renounced the right to use the resource, the device assigned to the arbiter is not granted the right to use the resource;
When the priority request information generation / holding means of the own arbiter generates priority request information, and the device assigned to the own arbiter has the highest priority, it is assigned to the device assigned to the own arbiter. Give the right to use the resource,
When the priority request information generation / holding means of the own arbiter is generating the priority request information, the device of another arbiter that has generated the priority request information rather than the priority of the device assigned to the own arbiter If the priority of the device is high, the right to use is not granted to the device assigned to its arbiter.
Arbitration determination means (13, 14) for determining
Have
An arbitration device that grants the use permission of the resource to a device assigned to the arbiter from an arbiter of an arbitration determination unit that has determined whether to give a usage right.

2. The arbitration device according to claim 1, wherein said priority request information generation / holding means has a shift register, and when its own arbiter obtains the right to use said resource, another device generated at the same time. Data indicating the abandonment of usage rights is stored in the shift register by a predetermined number according to the number of use requests for the resource, and the data stored in the shift register each time arbitration occurs The arbitration device is characterized by notifying the arbitration determination means of the own arbiter that the arbiter has abandoned the right to use by shifting the arbiter.

3. The arbitration device according to claim 2, wherein when the own arbiter obtains the right to use the resource, priority request information is stored in the shift register subsequent to the data indicating the waiver of the right to use the resource. When the arbiter fails to obtain the right to use the resource, the data stored in the shift register is shifted, and the priority request information is stored in the shift register following the previous stored data. An arbitration device characterized by that.

4. The arbitration device according to claim 3, wherein the last storage area of the shift register is associated with the value of data stored in the previous storage area and its own arbiter. Even if a priority request has been generated so far by storing the logical calculation result of whether or not there is a use request from the resource that has been assigned, the use request from the resource associated with the own arbiter An arbitration device, wherein the priority request information generation / holding means does not generate priority request information when there is not.

In a system in which resources are shared by a plurality of devices, when use requests for the resources are sent from the plurality of devices at the same time, among the plurality of devices that have sent the use requests according to a predetermined priority order for the devices. There is an arbitration method of an arbitration device that gives the right to use the resource to the highest priority device, and the arbitration device includes:
A plurality of arbiters equal in number to the plurality of devices, each of the plurality of arbiters being associated with each of the plurality of devices and pre-arbitrated for a device assigned to itself A plurality of arbiters (2-1 to 2-4) that give the right to use the resource according to conditions;
The predetermined arbitration condition is predetermined according to the number of use requests for the resources of other devices generated at the same time when the device assigned to the arbiter obtains the use right. After that, the right to use the device assigned to its own arbiter is relinquished, and if the right to use is not relinquished, the device assigned to its own arbiter has its highest priority. And granting the right to use the resource to the device assigned to
Each of the plurality of arbiters has priority request information generation / holding means (11, 12) and arbitration determination means (13, 14),
The priority for asserting the next use right of the resource to another arbiter when the use right is not abandoned and the use right is not obtained by the priority request information generation / holding means. Generate and hold request information, and generate and hold information indicating waiver of the usage right while waiving the right to use the resource,
Each time a request for using the plurality of devices for the shared resource occurs, priority request information for the current arbitration is received from the other arbiter,
If the arbiter has renounced the right to use the resource, the device assigned to the arbiter is not granted the right to use the resource;
When the priority request information generation / holding means of the own arbiter generates priority request information, and the device assigned to the own arbiter has the highest priority, it is assigned to the device assigned to the own arbiter. Give the right to use the resource,
When the priority request information generation / holding means of the own arbiter is generating the priority request information, the device of another arbiter that has generated the priority request information rather than the priority of the device assigned to the own arbiter If the priority of the device is high, the right to use is not granted to the device assigned to its arbiter.
Is determined by the arbitration determination means,
An arbitration method for an arbitration device, wherein an arbitration determination unit that determines whether to give a right to use grants permission to use the resource to a device assigned to the arbiter.

6. The arbitration method for an arbitration device according to claim 5, wherein said priority request information generation / holding means has a shift register, and when its own arbiter has obtained the right to use said resource, it occurred at the same time. Data indicating the abandonment of usage rights is stored in the shift register by a predetermined number according to the number of usage requests for the resource of other devices, and thereafter stored in the shift register every time arbitration occurs. The arbitration method of the arbitration apparatus is characterized in that the arbitration determination means of the own arbiter is informed that the own arbiter has abandoned the right to use by shifting the data thus obtained.

7. The adjustment method for an arbitration device according to claim 6, wherein when the arbiter obtains the right to use the resource, priority request information is stored in the shift register following the data indicating the waiver of the right to use. Thereafter, when arbitration occurs and the own arbiter fails to obtain the right to use the resource, the data stored in the shift register is shifted, and the priority request information is subsequently updated to the stored data. Specially stored in the shift register An arbitration method for an arbitration device, characterized by comprising:

8. The arbitration method of the arbitration device according to claim 7, wherein the last storage area of the shift register is a resource associated with a value of data stored in the previous storage area and its own arbiter. If there is no use request from the resource associated with its own arbiter this time, even if a priority request has been generated so far, by storing the logical calculation result with and without use request from An arbitration method for an arbitration device, characterized in that the priority request information generation / holding means does not generate priority request information.