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Message-ID: <79fd7c1d-2d3a-46b4-8a0c-56bfda036a94@amd.com>
Date: Fri, 21 Jun 2024 14:19:13 +0530
From: Dhananjay Ugwekar <Dhananjay.Ugwekar@....com>
To: K Prateek Nayak <kprateek.nayak@....com>
Cc: linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-hardening@...r.kernel.org, ananth.narayan@....com,
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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,
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gustavoars@...nel.org
Subject: Re: [PATCH v2 0/9] Add per-core RAPL energy counter support for AMD
CPUs
Hello Prateek,
On 6/21/2024 1:54 PM, K Prateek Nayak wrote:
> 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.
I think my assumption that topology_core_id() will return a unique core ID
across the system might not be correct. It seems the core ID is unique only
within a package, will fix this in the next version.
Thanks a lot for testing and helping narrow down the issue!
Regards,
Dhananjay
> >>
>> 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..]
>>
>
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