Messages in this thread | | | Subject | Re: [RFC PATCHv3] perf tools: add event grouping capability to "perf stat" | From | Peter Zijlstra <> | Date | Thu, 25 Nov 2010 15:02:00 +0100 |
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On Thu, 2010-11-25 at 14:19 +0100, Stephane Eranian wrote:
> I think using PERF_SAMPLE_READ may expose a problem in the > perf.data format. To correctly parse a sample created with SAMPLE_READ, > you need to know the attr.read_format. But for that you need to know the > event which caused the sample, but for that you need the SAMPLE_ID, > and you don't know if it's there or not. In other words, there is a chicken > and egg problem. > > I think the issue is that PERF_RECORD_SAMPLE is missing a mandatory > piece of information: overflow event ID. This must a mandatory field, not > optional as it is today. It is okay when you have only one group, but we'd > like to go beyond that.
I'm not sure I get it, there's both PERF_FORMAT_ID and PERF_SAMPLE_ID, so afaict there's a working combination for what you want to do.
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