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    SubjectRe: [PATCH][RESEND] Export per-tid and per-tgid cputime in nanoseconds.
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    On Mon, 2010-03-01 at 07:44 -0800, Divyesh Shah wrote:
    > On Sat, Feb 27, 2010 at 3:43 AM, Peter Zijlstra <peterz@infradead.org> wrote:
    > >
    > > On Fri, 2010-02-26 at 18:03 -0800, Divyesh Shah wrote:
    > > > This can be used by applications to get finer granularity cputime usage on
    > > > platforms that use timestamp counters or HPET.
    > >
    > > I guess the patch looks good, I'm just not sure what HPET got to do with
    > > anything.. the scheduler certainly doesn't use HPET for timekeeping, its
    > > terribly slow to read.
    >
    > Yes you're right. Please ignore the HPET comment.
    >
    > >
    > > Also, it would be good to get some more justification than 'some
    > > applications can use this', which is basically a truism for any patch
    > > that adds a user interface.
    >
    > 1) This should be useful for a shared or virtualized environment where
    > the shared management infrastructure needs to charge each application
    > as accurately as possible for cpu usage.
    > 2) An application that services different users and does some
    > cpu-intensive work may want to measure cpu time spent for each user by
    > the serving thread.
    >
    > I think applications like web servers, remote database servers, etc.
    > fit into the second category.
    >
    > For units of work smaller than a jiffy, this really helps as some
    > threads could potentially hide from the jiffy based accounting.
    >
    > Please let me know if you want me to send the patch again with the
    > corrected description and added justification.


    Its all should and may, anything concrete?

    Also, doesn't muck like schedstat, task_delay_accounting, cpuacct-cgroup
    or some other stuff expose this number already?



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