Merge tag 'perf-c2c-for-mingo-20161021' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core
Pull new 'perf c2c' tool from Arnaldo Carvalho de Melo:
- The 'perf c2c' tool provides means for Shared Data C2C/HITM analysis.
It allows you to track down cacheline contention. The tool is based
on x86's load latency and precise store facility events provided by
Intel CPUs.
It was tested by Joe Mario and has proven to be useful, finding some
cacheline contentions. Joe also wrote a blog about c2c tool with
examples:
https://joemario.github.io/blog/2016/09/01/c2c-blog/
Excerpt of the content on this site:
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At a high level, “perf c2c” will show you:
* The cachelines where false sharing was detected.
* The readers and writers to those cachelines, and the offsets where those accesses occurred.
* The pid, tid, instruction addr, function name, binary object name for those readers and writers.
* The source file and line number for each reader and writer.
* The average load latency for the loads to those cachelines.
* Which numa nodes the samples a cacheline came from and which CPUs were involved.
Using perf c2c is similar to using the Linux perf tool today.
First collect data with “perf c2c record” Then generate a report output with “perf c2c report”
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There one finds extensive details on using the tool, with tips on
reducing the volume of samples while still capturing enough to do
its job. (Dick Fowles, Joe Mario, Don Zickus, Jiri Olsa)
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
