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Date: Wed, 1 Jun 2022 18:25:05 +0800
From: Leo Yan <leo.yan@...aro.org>
To: Joe Mario <jmario@...hat.com>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...hat.com>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>, Alyssa Ross <hi@...ssa.is>,
Ian Rogers <irogers@...gle.com>, Like Xu <likexu@...cent.com>,
Kajol Jain <kjain@...ux.ibm.com>,
Li Huafei <lihuafei1@...wei.com>,
Adam Li <adam.li@...erecomputing.com>,
German Gomez <german.gomez@....com>,
James Clark <james.clark@....com>,
Ali Saidi <alisaidi@...zon.com>,
linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 00/12] perf c2c: Support display for Arm64
Hi Joe,
On Tue, May 31, 2022 at 02:44:07PM -0400, Joe Mario wrote:
[...]
> Hi Leo:
> I built a new perf with your patches and ran it on a 2-numa node Neoverse platform.
> I then ran my simple test that creates reader and writer threads to tug on the same cacheline.
> The c2c output is appended below.
>
> The output looks good, especially where you've broken out the (average) cycles for local and remote peer loads.
> And I'm glad to see you fixed the "Node" column. I use that a lot to help detect remote node accesses.
Thanks a lot for your testing and suggestions, which are really helpful!
> And the "PA cnt" field is working as well, which is important to see if numa_balance is moving the data around.
Good to know this. To be honest, before I didn't note for "PA cnt"
metric, I checked a bit for the code, this metrics is very useful to
understand how it's severe that a cache line is accessed from different
addresses, so we can get sense how a cache line is hammered.
> =================================================
> Shared Data Cache Line Table
> =================================================
> #
> # ----------- Cacheline ---------- Peer ------- Load Peer ------- Total Total Total --------- Stores -------- ----- Core Load Hit ----- - LLC Load Hit -- - RMT Load Hit -- --- Load Dram ----
> # Index Address Node PA cnt Snoop Total Local Remote records Loads Stores L1Hit L1Miss N/A FB L1 L2 LclHit LclHitm RmtHit RmtHitm Lcl Rmt
> # ..... .................. .... ...... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ....... ........ ....... ........ ....... ........ ........
> #
> 0 0x422140 0 6904 74.86% 137 131 6 148008 144970 3038 0 0 3038 0 144833 120 11 0 6 0 0 0
> 1 0xffffd976e63ae5c0 1 6 3.83% 7 7 0 15 15 0 0 0 0 0 8 4 3 0 0 0 0 0
> 2 0xffff07ffbf290980 0 5 2.19% 4 2 2 14 14 0 0 0 0 0 10 1 1 0 2 0 0 0
> 3 0xffffd976e57275c0 1 1 0.55% 1 1 0 1 1 0 0 0 0 0 0 1 0 0 0 0 0 0
> 4 0xffffd976e6071c00 1 3 0.55% 1 0 1 4 4 0 0 0 0 0 3 0 0 0 1 0 0 0
> [snip]
> =================================================
> Shared Cache Line Distribution Pareto
> =================================================
> #
> # -- Peer Snoop -- ------- Store Refs ------ --------- Data address --------- ---------- cycles ---------- Total cpu Shared
> # Num Rmt Lcl L1 Hit L1 Miss N/A Offset Node PA cnt Code address rmt peer lcl peer load records cnt Symbol Object Source:Line Node
> # ..... ....... ....... ....... ....... ....... .................. .... ...... .................. ........ ........ ........ ....... ........ .......................... ....... ......................... ....
> #
> ----------------------------------------------------------------------
> 0 6 131 0 0 3038 0x422140
> ----------------------------------------------------------------------
> 0.00% 0.00% 0.00% 0.00% 52.60% 0x8 0 1 0x400e6c 0 0 0 1598 4 [.] writer tugtest tugtest.c:152 0 1
> 0.00% 0.00% 0.00% 0.00% 47.40% 0x10 0 1 0x400e7c 0 0 0 1440 4 [.] writer tugtest tugtest.c:153 0 1
> 33.33% 75.57% 0.00% 0.00% 0.00% 0x20 0 1 0x401018 4095 3803 3419 409 4 [.] reader tugtest tugtest.c:187 0 1
> 66.67% 24.43% 0.00% 0.00% 0.00% 0x28 0 1 0x401034 4095 3470 3643 413 4 [.] reader tugtest tugtest.c:187 0 1
>
> ----------------------------------------------------------------------
> 1 0 7 0 0 0 0xffffd976e63ae5c0
> ----------------------------------------------------------------------
> 0.00% 57.14% 0.00% 0.00% 0.00% 0x0 1 1 0xffffd976e4815fbc 0 1333 0 4 2 [k] ktime_get [kernel.kallsyms] seqlock.h:276 1
> 0.00% 14.29% 0.00% 0.00% 0.00% 0x0 1 1 0xffffd976e4816d10 0 266 794 4 3 [k] ktime_get_update_offsets_n [kernel.kallsyms] seqlock.h:276 0 1
> 0.00% 28.57% 0.00% 0.00% 0.00% 0x30 1 1 0xffffd976e4816d20 0 87 150 4 3 [k] ktime_get_update_offsets_n [kernel.kallsyms] timekeeping.c:2298 0 1
>
> ----------------------------------------------------------------------
> 2 2 2 0 0 0 0xffff07ffbf290980
> ----------------------------------------------------------------------
> 50.00% 100.00% 0.00% 0.00% 0.00% 0x4 0 1 0xffffd976e47d2bdc 1217 1600 1147 4 3 [k] queued_spin_lock_slowpath [kernel.kallsyms] qspinlock.c:511 0 1
> 50.00% 0.00% 0.00% 0.00% 0.00% 0x4 0 1 0xffffd976e47d2a2c 4033 0 0 1 1 [k] queued_spin_lock_slowpath [kernel.kallsyms] qspinlock.c:382 0 1
>
> ----------------------------------------------------------------------
>
> Thanks for doing this. It looks good.
You are welcome! And very appreicate your helping to mature the code.
> I'll assume someone else is reviewing your code changes.
Yeah, let's give a bit more time for reviewing.
Thanks,
Leo
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