Re: [PATCH V6 08/17] perf tools: Add Intel PT support

From: Arnaldo Carvalho de Melo
Date: Fri Jun 26 2015 - 16:34:29 EST


Em Fri, Jun 26, 2015 at 09:48:20AM +0300, Adrian Hunter escreveu:
> On 26/06/15 03:09, Arnaldo Carvalho de Melo wrote:
> > Em Thu, Jun 25, 2015 at 08:56:34PM -0300, Arnaldo Carvalho de Melo escreveu:
> >> Will do the same tests with intel_pt as well, on a remote machine, add examples
> >> to the changeset logs and everything going well, aim for pushing for Ingo soon,
> >
> > So, I asked for callchains, with:
> >
> > perf record -g -e intel_bts// ls
> >
> > And it got stuck somewhere, then I did a perf top to see where it was,
> > and got to:
> >
> > 96.24% perf [.] intel_bts_process_queue
> >
> > Annotating I get to:
> >
> > 1.17 â1a0:âââmov 0x8(%r13),%rdx
> > â â test %rdx,%rdx
> > 98.83 â âââje 1a0
> >
> >
> > Which is an endless loop! Source code for intel_bts_process_buffer(),
> > inlined there:
> >
> > while (sz > sizeof(struct branch)) {
> > if (!branch->from && !branch->to)
> > continue;
> > err = intel_bts_synth_branch_sample(btsq, branch);
> > if (err)
> > break;
> > branch += 1;
> > sz -= sizeof(struct branch);
> > }
> >
> > Can you fix this, please, so that I can fold it into where it was
> > introduced, namely:
> >
> > commit 439ad895a2aecea09416206f023336297cc72efe
> > Author: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > Date: Fri May 29 16:33:39 2015 +0300
> >
> > perf tools: Add Intel BTS support
>
> It is fixed as an unexpected side-effect of a following patch (which is probably why I didn't notice it - or perhaps I rolled the fix into the wrong patch O_o). The fix is in:
>
> perf tools: Output sample flags and insn_len from intel_bts
>
> intel_bts synthesizes samples. Fill in the new flags and insn_len
> members with instruction information.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>
>
> So what you want is:

Ok, folded that, fixed the problem, moving on...

- Arnaldo
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