Hi Davesh,
1. The promoteDeferredTargets is a “trick” used in the classic memory system where MSHR targets gets put “on hold” if we already have a target outstanding that will e.g. give us a block in modified or owned state. Once the first chunk of targets are resolved, and all caches agree on the new state, we then continue with the deferred targets (after promoting them). Thus, the deferred targets are serialised with respect to the normal targets, simplifying any intermittent states. 2. When the queue is full, we block the cpu-side port. This is quite crude, as there could be hits that would have been fine. However, at the moment we take the easy way out.Have a look at setBlocked and recvTimingReq. I hope that helps. Andreas From: gem5-users <gem5-users-boun...@gem5.org<mailto:gem5-users-boun...@gem5.org>> on behalf of Davesh Shingari <shingaridav...@gmail.com<mailto:shingaridav...@gmail.com>> Reply-To: gem5 users mailing list <gem5-users@gem5.org<mailto:gem5-users@gem5.org>> Date: Tuesday, 14 July 2015 18:59 To: gem5 users mailing list <gem5-users@gem5.org<mailto:gem5-users@gem5.org>> Subject: [gem5-users] MSHR Queue Full Handling Hi In cache_impl.hh, I can see that MSHRQueue *mq = mshr->queue; bool wasFull = mq->isFull(); But wasFull is used only in following code: if (mshr->promoteDeferredTargets()) { // avoid later read getting stale data while write miss is // outstanding.. see comment in timingAccess() if (blk) { blk->status &= ~BlkReadable; } mq = mshr->queue; mq->markPending(mshr); requestMemSideBus((RequestCause)mq->index, clockEdge() + pkt->lastWordDelay); } else { mq->deallocate(mshr); if (wasFull && !mq->isFull()) { clearBlocked((BlockedCause)mq->index); } I have 2 questions: 1. What does promoteDeferredTargets function do? 2. What happens when the queue is full. For eg. In Caches.py I can see that mshr for L2 is 20. What happens when the misses number exceeds 20? Can someone point me to the handling code? -- Have a great day! Thanks and Warm Regards Davesh Shingari Master's in Computer Engineering [EE] Arizona State University dshin...@asu.edu<mailto:dshin...@asu.edu> [https://mailfoogae.appspot.com/t?sender=ac2hpbmdhcmlkYXZlc2hAZ21haWwuY29t&type=zerocontent&guid=e27518a8-bc81-44ec-9b38-b67dc2b02b09]ᐧ -- IMPORTANT NOTICE: The contents of this email and any attachments are confidential and may also be privileged. If you are not the intended recipient, please notify the sender immediately and do not disclose the contents to any other person, use it for any purpose, or store or copy the information in any medium. Thank you. ARM Limited, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2557590 ARM Holdings plc, Registered office 110 Fulbourn Road, Cambridge CB1 9NJ, Registered in England & Wales, Company No: 2548782
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