Messages in this thread | | | Date | Wed, 05 Nov 2014 17:46:10 +0900 | From | Masami Hiramatsu <> | Subject | Re: Re: [PATCH perf/core 0/6] perf-probe: Bugfix and add new options for cache |
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(2014/11/05 15:23), Namhyung Kim wrote: > On Wed, 05 Nov 2014 01:22:46 +0900, Masami Hiramatsu wrote: >> (2014/11/04 23:38), Arnaldo Carvalho de Melo wrote: >>> Em Tue, Nov 04, 2014 at 01:36:31PM +0900, Masami Hiramatsu escreveu: >>>> OK, I agree using .debug/.buildid/ to store caches. >>>> Here is what I'm thinking, >>> >>>> # this makes caches for given pattern instead of adding probes. >>>> perf probe --cache '* $params' >>> >>>> # the cache is stored in .debug/.buildid/<buildid>.probe >>>> # the cache entry can be queried by buildid and eventname >>> >>> To follow the existing standard this would instead go to: >>> >>>> # the cache is stored in .debug/probes/path/to/dso/name/buildid >>>> # And can be found via its buildid link .debug/.buildid/bu/ildid -> ../../probes/path/to/dso/name/buildid >> >> Ah, I see. so you meant adding a top-level .debug/probes/ dir. >> But in that case, shouldn't we change .debug/.buildid/bu/ildid to >> .debug/probes/.buildid/bu/ildid ? > > Either is fine to me. But my concern is that it might be bloated as > system/package update is going on, so we need to control it somehow. > That's why I suggested the probe-cache command.
Yes, that is also my question. Should we really have 3 cache management commands? At the first step, maybe we can have those as separated, but it would better be consolidated to one perf-cache command, I think.
>>>> perf probe --query ${remote_buildid}:do_fork >>>> p:probe/do_fork _text+298722 clone_flags=%di:u64 stack_start=%si:u64 stack_size=%dx:u64 parent_tidptr=%cx:u64 child_tidptr=%r8:u64 >>> >>>> # or perf can set it up directly to local >>>> perf probe --query-add do_fork >>> >>> You missed the build id above, no? I.e. it would be: >>> >>>> # or perf can set it up directly to local >>>> perf probe --query-add ${remote_buildid}:do_fork >> >> No, since this command set the event to local machine, perf-probe >> should check the local build-id and query the appropriate event >> from the cache. >> # BTW, maybe we'd better use perf probe --add '$do_fork' (calls >> # "cache of do_fork") instead of long --query-add. :) > > It should take care of uprobe case too. So simple do_fork should have > group/event or provider/marker form instead so that it can help to find > which binary defines the cached event. Maybe we also need to keep a > event-to-binary table and then check (current?) build-id somehow to > identify correct event to be used. >
Good catch! :)
perf probe --add '$group:event $params' # for cached event perf probe --add '%provider[@path]:marker $params' # for SDT event
and these are automatically check the build-id.
> Also this function entry level event cache can be used with uprobes..
Yes, of course :)
Thank you,
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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