Messages in this thread | | | Date | Thu, 1 Dec 2011 16:15:20 +0100 | From | Robert Richter <> | Subject | Re: [PATCH] perf: make perf.data more self-descriptive (v8) |
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On 01.12.11 16:01:55, Frederic Weisbecker wrote: > On Wed, Nov 30, 2011 at 02:49:46PM -0200, acme@redhat.com wrote: > > Em Wed, Nov 30, 2011 at 04:08:29PM +0100, Robert Richter escreveu: > > > On 29.11.11 10:35:24, Stephane Eranian wrote: > > > > sec_start = header->data_offset + header->data_size; > > > > lseek(fd, sec_start + sec_size, SEEK_SET); > > > > > > > > err = do_write_feat(fd, header, HEADER_TRACE_INFO, &p, evlist); > > > > if (err) > > > > goto out_free; > > > > > > > > err = do_write_feat(fd, header, HEADER_BUILD_ID, &p, evlist); > > > > if (err) { > > > > perf_header__clear_feat(header, HEADER_BUILD_ID); > > > > goto out_free; > > > > } > > > > > > The 'clear_feat' is missing for TRACE_INFO, that's all. The question is: > > > > is case do_write_feat(trace_info) fails, is there still a way to parse the file > > > > correctly? If not, then perf should bail out, if yes, then we need to add the > > > > clear_feat(TRACE_INFO) in case of error. > > > > > The question is, if do_write_feat() fails for HEADER_TRACE_INFO or > > > HEADER_BUILD_ID then perf_header__adds_write() fails. A failure of any > > > other feature simple disables it by calling clear_feat(). I noticed > > > this asymmetry and wonder why? > > Not sure either. I must confess I didn't write that fixup part...
I am asking this because I want to change code in a way that treats all features the same, that is just to disable the feature bit on failure and then continue anyway.
> > > > > > > Also, is there a reason why HEADER_TRACE_INFO starts with bit 1 instead > > > of bit 0. Is bit 0 reserved for some reason? > > Looks like a mistake I made from the beginning. And we can't really fix that > without breaking all perf.data :)
Ok, wasn't sure if the bit was used for other purposes, but seems to be always zero then.
Thanks,
-Robert
-- Advanced Micro Devices, Inc. Operating System Research Center
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