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mrmeswani
Journeyman III

Profiling L3 counters on AMD EPYC

I have a system with AMD EPYC 7551 32-Core Processor running Ubuntu and with AMDuProf installed

I have been trying to collect L3 counters but i get the following message

Running the example cmd in uProf User guide

AMDuProfCLI collect -e event=timer,interval=1 -e event=0xb001,umask=0x80,slicemask=0xF,threadmask=0xFF -a -d 10

There was a problem configuring the L3 profile event(0xb001).

Also tried the command posted in another discussion thread

./AMDuProfCLI collect -e event=timer,interval=1 -e event=0xb006,umask=0x01,slicemask=0xF,threadmask=0xFF -a -d 10 -o /tmp/out

There was a problem configuring the L3 profile event(0xb006).

Why is this counter not working ? I am running as root.

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5 Replies
linux_monkey
Staff
Staff

Re: Profiling L3 counters on AMD EPYC

Recall that EPYC implements multiple L3 caches where each L3 is part of a Compute Complex (CCX). When you are collecting thread counts you need to specify which CCX for which you want to collect L3 counts.

Please try a threadmask where the only set bit is the first CPU in the CCX you wish to profile (e.g. CPU 0 for CCX0 on die 0 socket 0, CPU 4 on a 32 core part for CCX1 on die 0 socket 0). The lstopo program from the Portable Hardware Locality library (hwloc) on Linux is handy for showing you which CPUs are sharing which L3.

Not 100% sure this is your problem, but even if not, this may be helpful.

-Monkey

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mrmeswani
Journeyman III

Re: Profiling L3 counters on AMD EPYC

I tried with different threadmasks like Ox01 , but I still get the same error. I want to profile and L3 miss counts from all slices, are you able to collect L3 misses on your system, if so can you share the profiling command?

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swarup
Staff
Staff

Re: Profiling L3 counters on AMD EPYC

L3 profiling is not yet supported on Linux platforms, so far supported only on Windows platforms. This is in our pipeline and should be available in the future releases.

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mrmeswani
Journeyman III

Re: Profiling L3 counters on AMD EPYC

What counters are functional in Linux? Can we also know which counters are DF ?

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swarup
Staff
Staff

Re: Profiling L3 counters on AMD EPYC

L3/DF counters are not supported on Linux yet.To get the list of supported events on a system, please use the command "./AMDuProfCLI collect --list cpu-events". The list of supported events might be different on different systems/platforms.

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