Messages in this thread | | | Subject | Re: [PATCH 6/9] perf report: Support instruction latency | From | "Liang, Kan" <> | Date | Fri, 5 Feb 2021 09:51:24 -0500 |
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On 2/5/2021 7:55 AM, Athira Rajeev wrote: >>> Because in other archs, the var2_w of ‘perf_sample_weight’ could be used to capture something else than the Local INSTR Latency. >>> Can we have some weak function to populate the header string ? >> I agree that the var2_w has different meanings among architectures. We should not force it to data->ins_lat. >> >> The patch as below should fix it. Does it work for you? > My point about weak function was actually for the arch specific header string. But I guess we should not force it to data->ins_lat
Yes, I don't think PowerPC should force var2_w to data->ins_lat. I think you can create your own field.
> as you mentioned. I checked the below patch defining an ‘arch_perf_parse_sample_weight' for powerpc and it works. > > But one observation is that, for cases with kernel having support for PERF_SAMPLE_WEIGHT_STRUCT but missing arch specific support for ‘arch_perf_parse_sample_weight', it will report ‘Local Weight’ wrongly since weak function takes it as 64 bit. Not sure if that is a valid case to consider though.
Currently, the PERF_SAMPLE_WEIGHT_STRUCT is only enabled on X86 by default. https://lore.kernel.org/lkml/1612296553-21962-6-git-send-email-kan.liang@linux.intel.com/
For PowerPC, the PERF_SAMPLE_WEIGHT is still the default setting. There is no way to set PERF_SAMPLE_WEIGHT_STRUCT via perf tool. I don't think the above case will happen.
Thanks, Kan
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