Re: [RFC PATCH -tip 0/2 v3] pagecache tracepoints proposal

From: Keiichi KII
Date: Fri Feb 05 2010 - 16:20:59 EST


Hello,

(02/05/10 02:28), Ingo Molnar wrote:
> Looks really nice IMO! It also demonstrates nicely the extensibility via
> Tom's perf trace scripting engine. (which will soon get a Python script
> engine as well, so Perl and C wont be the only possibility to extend perf
> with.)
>
> I've Cc:-ed a few parties who might be interested in this. Wu Fengguang has
> done MM instrumentation in this area before - there might be some common
> ground instead of scattered functionality in /proc, debugfs, perf and
> elsewhere?
>
> Note that there's also these older experimental commits in tip:tracing/mm
> that introduce the notion of 'object collections' and adds the ability to
> trace them:
>
> 3383e37: tracing, page-allocator: Add a postprocessing script for page-allocator-related ftrace events
> c33b359: tracing, page-allocator: Add trace event for page traffic related to the buddy lists
> 0d524fb: tracing, mm: Add trace events for anti-fragmentation falling back to other migratetypes
> b9a2817: tracing, page-allocator: Add trace events for page allocation and page freeing
> 08b6cb8: perf_counter tools: Provide default bfd_demangle() function in case it's not around
> eb46710: tracing/mm: rename 'trigger' file to 'dump_range'
> 1487a7a: tracing/mm: fix mapcount trace record field
> dcac8cd: tracing/mm: add page frame snapshot trace
>
> this concept, if refreshed a bit and extended to the page cache, would allow
> the recording/snapshotting of the MM state of all currently present pages in
> the page-cache - a possibly nice addition to the dynamic technique you apply
> in your patches.
> there's similar "object collections" work underway for 'perf lock' btw., by
> Hitoshi Mitake and Frederic.
>
> So there's lots of common ground and lots of interest.
>
> Btw., instead of "perf trace record pagecache-usage", you might want to think
> about introducing a higher level tool as well: 'perf mm' or 'perf pagecache'
> - just like we have 'perf kmem' for SLAB instrumentation, 'perf sched' for
> scheduler instrumentation and 'perf lock' for locking instrumentation. [with
> 'perf timer' having been posted too.]
>
> 'perf mm' could then still map to Perl scripts, it's just a convenience. It
> could then harbor other MM related instrumentation bits as well. Just an idea
> - this is a possibility, if you are trying to achieve higher organization.

Thank you for your information about "perf lock" and "tip:tracing/mm" things.
I think it's very useful to merge 'object collections' about tracing/mm into
"perf mm". So, I will introduce a higer level tool like "perf mm" for the
mm related things as next step.
These will help me implement "perf mm".

And tom's perf trace scripting engine is very flexible.
I will try to implement "perf mm" based on his scripting engine and
harbor other MM related instrumentation like the above if I can.

Thanks,
Keiichi
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