Messages in this thread | | | From | Namhyung Kim <> | Subject | Re: [PATCH perf/core 0/6] perf-probe: Bugfix and add new options for cache | Date | Wed, 05 Nov 2014 15:23:44 +0900 |
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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.
> >> >>> 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.
Also this function entry level event cache can be used with uprobes..
Thanks, Namhyung
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