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Message-ID: <a26b9774-f9da-763e-aebf-5d66a6d44377@amd.com>
Date: Fri, 21 Jun 2024 13:54:22 +0530
From: K Prateek Nayak <kprateek.nayak@....com>
To: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
CC: <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
<linux-hardening@...r.kernel.org>, <ananth.narayan@....com>,
<gautham.shenoy@....com>, <ravi.bangoria@....com>, <sandipan.das@....com>,
<linux-pm@...r.kernel.org>, <rui.zhang@...el.com>,
<oleksandr@...alenko.name>, <peterz@...radead.org>, <mingo@...hat.com>,
<acme@...nel.org>, <namhyung@...nel.org>, <mark.rutland@....com>,
<alexander.shishkin@...ux.intel.com>, <jolsa@...nel.org>,
<irogers@...gle.com>, <adrian.hunter@...el.com>, <kan.liang@...ux.intel.com>,
<tglx@...utronix.de>, <bp@...en8.de>, <dave.hansen@...ux.intel.com>,
<x86@...nel.org>, <kees@...nel.org>, <gustavoars@...nel.org>
Subject: Re: [PATCH v2 0/9] Add per-core RAPL energy counter support for AMD
CPUs
Hello Dhananjay,
On 6/20/2024 6:26 PM, Dhananjay Ugwekar wrote:
> Currently the energy-cores event in the power PMU aggregates energy
> consumption data at a package level. On the other hand the core energy
> RAPL counter in AMD CPUs has a core scope (which means the energy
> consumption is recorded separately for each core). Earlier efforts to add
> the core event in the power PMU had failed [1], due to the difference in
> the scope of these two events. Hence, there is a need for a new core scope
> PMU.
>
> This patchset adds a new "power_per_core" PMU alongside the existing
> "power" PMU, which will be responsible for collecting the new
> "energy-per-core" event.
>
> Tested the package level and core level PMU counters with workloads
> pinned to different CPUs.
>
> Results with workload pinned to CPU 1 in Core 1 on an AMD Zen4 Genoa
> machine:
>
> $ perf stat -a --per-core -e power_per_core/energy-per-core/ sleep 1
When testing this on a 2P 3rd Generation EPYC System (2 x 64/128T), I
ran into an issue where it seems like the energy reporting for the
system is coming from the second socket. Following are the CPUs on each
socket of the system:
Node 0: 0-63, 128-191
Node 1: 64-127, 192-255
Following are the experiments I ran:
$ # Run a busy loop on each thread of the first socket
$ for i in `seq 0 63` `seq 128 191`; do taskset -c $i ~/scripts/loop & done
$ sudo perf stat -a --per-core -e power_per_core/energy-per-core/ -- sleep 5
S0-D0-C0 1 0.00 Joules power_per_core/energy-per-core/
S0-D0-C1 1 0.00 Joules power_per_core/energy-per-core/
S0-D0-C2 1 0.00 Joules power_per_core/energy-per-core/
S0-D0-C3 1 0.00 Joules power_per_core/energy-per-core/
...
S0-D0-C63 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C0 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C1 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C2 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C3 1 0.00 Joules power_per_core/energy-per-core/
...
S1-D1-C63 1 0.00 Joules power_per_core/energy-per-core/
From the energy data, it looks as if the system is entirely idle.
If I repeat the same, pinning the running busy loop on the threads of
second socket, I see the following:
$ # Run a busy loop on each thread of the second socket
$ for i in `seq 64 127` `seq 192 255`; do taskset -c $i ~/scripts/loop & done
$ sudo perf stat -a --per-core -e power_per_core/energy-per-core/ -- sleep 5
S0-D0-C0 1 11.79 Joules power_per_core/energy-per-core/
S0-D0-C1 1 11.80 Joules power_per_core/energy-per-core/
S0-D0-C2 1 11.90 Joules power_per_core/energy-per-core/
S0-D0-C3 1 11.88 Joules power_per_core/energy-per-core/
...
S0-D0-C63 1 11.76 Joules power_per_core/energy-per-core/
S1-D1-C0 1 11.81 Joules power_per_core/energy-per-core/
S1-D1-C1 1 11.80 Joules power_per_core/energy-per-core/
S1-D1-C2 1 11.90 Joules power_per_core/energy-per-core/
S1-D1-C3 1 11.88 Joules power_per_core/energy-per-core/
...
S1-D1-C63 1 11.76 Joules power_per_core/energy-per-core/
The whole system seems to be busy this time around. I've verified that
only half the system is busy using htop in either case.
Running some more experiments, I see the following:
$ taskset -c 1 ~/scripts/loop& # First thread from Core 1, Socket
$ sudo perf stat -a --per-core -e power_per_core/energy-per-core/ -- sleep 5
S0-D0-C0 1 0.02 Joules power_per_core/energy-per-core/
S0-D0-C1 1 0.21 Joules power_per_core/energy-per-core/
S0-D0-C2 1 0.20 Joules power_per_core/energy-per-core/
S0-D0-C3 1 0.00 Joules power_per_core/energy-per-core/
...
(Seemingly idle system)
$ taskset -c 65 ~/scripts/loop&
$ sudo perf stat -a --per-core -e power_per_core/energy-per-core/ -- sleep 5
S0-D0-C0 1 0.01 Joules power_per_core/energy-per-core/
S0-D0-C1 1 16.73 Joules power_per_core/energy-per-core/
S0-D0-C2 1 0.00 Joules power_per_core/energy-per-core/
S0-D0-C3 1 0.00 Joules power_per_core/energy-per-core/
...
S0-D0-C63 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C0 1 0.01 Joules power_per_core/energy-per-core/
S1-D1-C1 1 16.73 Joules power_per_core/energy-per-core/
S1-D1-C2 1 0.00 Joules power_per_core/energy-per-core/
S1-D1-C3 1 0.00 Joules power_per_core/energy-per-core/
...
S1-D1-C63 1 0.00 Joules power_per_core/energy-per-core/
(Core 1 from both sockets look busy reporting identical energy
values)
Hope it helps narrow down the issue.
>
> Performance counter stats for 'system wide':
>
> S0-D0-C0 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C1 1 5.72 Joules power_per_core/energy-per-core/
> S0-D0-C2 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C3 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C4 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C5 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C6 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C7 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C8 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C9 1 0.02 Joules power_per_core/energy-per-core/
> S0-D0-C10 1 0.02 Joules power_per_core/energy-per-core/
>
> [1]: https://lore.kernel.org/lkml/3e766f0e-37d4-0f82-3868-31b14228868d@linux.intel.com/
>
> This patchset applies cleanly on top of v6.10-rc4 as well as latest
> tip/master.
P.S. I tested these changes on top of tip:perf/core
>
> [..snip..]
>
--
Thanks and Regards,
Prateek
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