Messages in this thread | | | Date | Thu, 19 May 2022 17:06:18 +0800 | Subject | Re: [PATCH v2 9/11] perf c2c: Sort on peer snooping for load operations | From | Adam Li <> |
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Hi Leo,
Thanks for the update. On 5/18/2022 2:12 PM, Leo Yan wrote:
> Please note, in the total statistics, all remote accesses will be > accounted into metric "rmt_hit", so "rmt_hit" includes the access for > remote DRAM or any upwards cache levels due we cannot distinguish > them. >
Agree that "Load Remote HIT" makes more sense than "Load Remote DRAM".
> From my experiment, with this updating the output result is promised > for the peer accesses and it's easier for inspecting false sharing. > > As you might see I have prepared a git repo: > https://git.linaro.org/people/leo.yan/linux-spe.git/ branch: > perf_c2c_arm_spe_peer_v3, which contains the updated patches for both > memory flag setting and perf c2c related patches. > > Could you confirm if the updated code works for you or not? >
I tested v3 patch (perf_c2c_arm_spe_peer_v3 branch) on 2P Altra system.
Compared with v2, "Snoop Peer" can better indicate cache false-sharing, for the 'false_sharing.exe' test case.
Bellow are details:
# perf c2c record -- numactl -m 0 ./false_sharing.exe 2 183 mticks, reader_thd (thread 2), on node 0 (cpu 78). 195 mticks, reader_thd (thread 3), on node 1 (cpu 124). 546 mticks, lock_th (thread 0), on node 0 (cpu 0). 562 mticks, lock_th (thread 1), on node 1 (cpu 123). [ perf record: Woken up 36 times to write data ] [ perf record: Captured and wrote 72.440 MB perf.data ]
# perf c2c report -d peer --coalesce tid,pid,iaddr,dso -N --stdio Warning: Arm SPE CONTEXT packets not found in the traces. Matching of TIDs to SPE events could be inaccurate. Warning: AUX data detected collision 20 times out of 168!
================================================= Total records : 1198728 Locked Load/Store Operations : 0 Load Operations : 1031196 Loads - uncacheable : 0 Loads - IO : 0 Loads - Miss : 0 Loads - no mapping : 0 Load Fill Buffer Hit : 0 Load L1D hit : 970636 Load L2D hit : 292 Load LLC hit : 2477 Load Local HITM : 0 Load Remote HITM : 0 Load Remote HIT : 56459 Load Local DRAM : 1332 Load Remote DRAM : 0 Load MESI State Exclusive : 1332 Load MESI State Shared : 0 Load LLC Misses : 57791 Load access blocked by data : 0 Load access blocked by address : 0 Load HIT Peer : 58814 LLC Misses to Local DRAM : 2.3% LLC Misses to Remote DRAM : 0.0% LLC Misses to Remote cache (HIT) : 97.7% LLC Misses to Remote cache (HITM) : 0.0% Store Operations : 167532 Store - uncacheable : 0 Store - no mapping : 0 Store L1D Hit : 0 Store L1D Miss : 0 Store No available memory level : 167532 No Page Map Rejects : 1234 Unable to parse data source : 0
================================================= Global Shared Cache Line Event Information ================================================= Total Shared Cache Lines : 45 Load HITs on shared lines : 226254 Fill Buffer Hits on shared lines : 0 L1D hits on shared lines : 166010 L2D hits on shared lines : 4 Load HITs on peer cache lines : 58814 LLC hits on shared lines : 2455 Locked Access on shared lines : 0 Blocked Access on shared lines : 0 Store HITs on shared lines : 96403 Store L1D hits on shared lines : 0 Store No available memory level : 96403 Total Merged records : 96403
================================================= c2c details ================================================= Events : arm_spe_0/ts_enable=1,load_filter=1,store_filter=1,min_latency=30/ : dummy:u : memory Cachelines sort on : Snoop Peers Cacheline data grouping : offset,tid,pid,iaddr,dso
================================================= Shared Data Cache Line Table ================================================= # # ----------- Cacheline ---------- Snoop ------- Load Hitm ------- Snoop Total Total Total --------- Stores -------- ----- Core Load Hit ----- - LLC Load Hit -- - RMT Load Hit -- --- Load Dram ---- # Index Address Node PA cnt Peer Total LclHitm RmtHitm Peer records Loads Stores L1Hit L1Miss N/A FB L1 L2 LclHit LclHitm RmtHit RmtHitm Lcl Rmt # ..... .................. .... ...... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ........ ....... ........ ....... ........ ........ # 0 0x420180 N/A 0 95.53% 0 0 0 56183 246056 219522 26534 0 0 26534 0 161914 0 106 0 56176 0 1326 0 1 0x420100 N/A 0 4.37% 0 0 0 2571 76437 6576 69861 0 0 69861 0 4005 0 2335 0 236 0 0 0 [...]
Thanks, -adam
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