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Date:   Wed, 21 Jun 2023 08:57:41 +0530
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Subject: Re: [PATCH] perf/amd: Prevent grouping of IBS events
To:     Ian Rogers <irogers@google.com>
Cc:     peterz@infradead.org, acme@kernel.org, jolsa@kernel.org,
        namhyung@kernel.org, bp@alien8.de, x86@kernel.org,
        linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
        sandipan.das@amd.com, ananth.narayan@amd.com,
        santosh.shukla@amd.com, Ravi Bangoria <ravi.bangoria@amd.com>
References: <20230620091603.269-1-ravi.bangoria@amd.com>
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From:   Ravi Bangoria <ravi.bangoria@amd.com>
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Hi Ian,

On 20-Jun-23 10:14 PM, Ian Rogers wrote:
> On Tue, Jun 20, 2023 at 2:16 AM Ravi Bangoria <ravi.bangoria@amd.com> wrote:
>>
>> IBS PMUs can have only one event active at any point in time. Restrict
>> grouping of multiple IBS events.
> 
> Thanks Ravi,
> 
> can you provide an example/test for this? Should this be a weak group issue?

Before:
  $ sudo ./perf record -e "{ibs_op//,ibs_op//}" -C 0
  ^C[ perf record: Woken up 1 times to write data ]
  [ perf record: Captured and wrote 0.540 MB perf.data (531 samples) ]

After:
  $ sudo ./perf record -e "{ibs_op//,ibs_op//}" -C 0
  Error:
  AMD IBS may only be available in system-wide/per-cpu mode.
  Try using -a, or -C and workload affinity

The error message is stale and misleading. I have a patch to fix it.
I'll post it separately.

Thanks,
Ravi