Messages in this thread | | | From | "Metzger, Markus T" <> | Date | Fri, 7 Aug 2009 12:34:46 +0100 | Subject | RE: [patch] x86, perf_counter, bts: add bts to perf_counter |
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>-----Original Message----- >From: Ingo Molnar [mailto:mingo@elte.hu] >Sent: Friday, August 07, 2009 1:20 PM >To: Metzger, Markus T >Cc: Peter Zijlstra; tglx@linutronix.de; hpa@zytor.com; markus.t.metzger@gmail.com; linux- >kernel@vger.kernel.org >Subject: Re: [patch] x86, perf_counter, bts: add bts to perf_counter > > >note, i had this running in the background, as root: > >/home/mingo/bin/perf top >/dev/null 2>/dev/null& > >that is what interacted most likely.
I'll try that, as well.
> I killed that task and did a >user-space only recording via: > >titan:~> perf record -f -e branches:u -c 1 ./loop_1b_instructions > >and that succeeded: > >^C[ perf record: Captured and wrote 827.901 MB perf.data (~36171547 samples) ] > >to make BTS sampling really practical we need a 'flight data >recorder' mode for the mmap buffer (overwrite mode), right? Peter >sent you a patch for that some time ago - did anything good happen >to that patch?
You mean the patch to find the beginning of the buffer?
Seems that we only get one type of record in those buffers, so a debugger can read the trace from tail to head.
I had been expecting that we can have multiple counters write into the same mmap buffer, but when I actually tried to do that, it looked like I would need a separate mmap buffer per counter.
thanks and regards, markus.
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