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From: Harald Servat <harald.servat@bsc.es>
To: linux-perf-users@vger.kernel.org
Subject: Latency = weigth in perf mem record/report?
Date: Thu, 13 Feb 2014 18:08:43 +0100	[thread overview]
Message-ID: <52FCFC1B.1000703@bsc.es> (raw)

Dear list,

   table 18-18 from the Vol 3b part 2 of the Intel® 64 and IA-32 
Architectures  Software Developer’s Manual (labeled as Table 18-18. PEBS 
Record Format for Intel Core i7 Processor Family ) [1] indicates that 
the PEBS samples report the latency value (in core cycles) for that 
particular load/store that emitted the sample at the address 0xa8 from 
the begin of the PEBS sample address.

   I've seen that there is a weight field in the output of the perf 
report -D associated to the PERF_RECORD_SAMPLE. Looking at the kernel 
code I found in file arch/x86/kernel/cpu/perf_event_intel_ds.c the 
following code which seems to be storing the info I want

  819         /*
  820          * Use latency for weight (only avail with PEBS-LL)
  821          */
  822         if (fll && (sample_type & PERF_SAMPLE_WEIGHT))
  823             data.weight = pebs->lat;

   and then in tools/perf/builtin-mem.c the routine dump_raw_samples 
seems to dump this info. Am I right? Can anyone kindly confirm this?

Thank you very much.

[1] 
http://www.intel.com/content/dam/www/public/us/en/documents/manuals/64-ia-32-architectures-software-developer-vol-3b-part-2-manual.pdf

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             reply	other threads:[~2014-02-13 17:08 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-02-13 17:08 Harald Servat [this message]
2014-02-17 16:02 ` Latency = weigth in perf mem record/report? Jiri Olsa

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