Re: [PATCH] perf/amd: Prevent grouping of IBS events

[Ravi Bangoria]

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@xxxxxxx> 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