Messages in this thread | | | Date | Tue, 21 Sep 2010 15:38:56 +0200 | Subject | Re: [RFC PATCH 0/2] perf_events: add support for per-cpu per-cgroup monitoring (v3) | From | Stephane Eranian <> |
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On Tue, Sep 21, 2010 at 2:42 PM, Peter Zijlstra <peterz@infradead.org> wrote: > On Tue, 2010-09-21 at 13:48 +0200, Stephane Eranian wrote: >> The main issue I see with this is that it relies on having at least one >> task in the cgroup when you start the measurement. That is certainly >> not always the case. > > Hmm, indeed. One thing we can do about that is move perf into the > cgroup, create the counter (disabled) using self to identify the cgroup, > move perf back to where it came from, and enable the counter. > Yes, that's another possibility. I wonder if there are any non-obvious difficulties with this approach. Is it as simple as: FILE *fp; fp = fopen("/dev/cgroup/test/tasks", "w"); fprintf(fp, "%d", gettid()); close(fp):
> Its just that I prefer to keep the attach state in the syscall arguments > and not the perf_event_attr struct. > I understand that.
> cgroups are task objects, so it makes sense to use the task attach to > indicate the cgroup. The empty cgroup case is indeed a tad unfortunate. > Not having to open more files and pass fds around was also a nice > benefit. > Sure.
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