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    SubjectRe: [tip:perf/core] tracing: Add unstable sched clock note to the warning
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    On Thu, 2011-02-17 at 18:18 +0100, Ingo Molnar wrote:
    > * Steven Rostedt <rostedt@goodmis.org> wrote:
    >
    > > On Thu, 2011-02-17 at 15:00 +0000, tip-bot for Jiri Olsa wrote:
    > > > Commit-ID: 5e38ca8f3ea423442eaafe1b7e206084aa38120a
    > > > Gitweb: http://git.kernel.org/tip/5e38ca8f3ea423442eaafe1b7e206084aa38120a
    > > > Author: Jiri Olsa <jolsa@redhat.com>
    > > > AuthorDate: Wed, 2 Feb 2011 13:28:18 +0100
    > > > Committer: Steven Rostedt <rostedt@goodmis.org>
    > > > CommitDate: Tue, 8 Feb 2011 11:57:22 -0500
    > > >
    > > > tracing: Add unstable sched clock note to the warning
    > > >
    > > > The warning "Delta way too big" warning might appear on a system with
    > > > unstable shed clock right after the system is resumed and tracing
    > > > was enabled during the suspend.
    > > >
    > > > Since it's not realy bug, and the unstable sched clock is working
    > > > fast and reliable otherwise, Steven suggested to keep using the
    > > > sched clock in any case and just to make note in the warning itself.
    > > >
    > >
    > >
    > > Peter Zijlstra just informed me on IRC that the commit:
    > >
    > > cd7240c0b900eb6d690ccee088a6c9b46dae815a
    > > x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep
    > > states
    > >
    > > Prevents the clock from going backwards triggering the warn on. If this
    > > is the case, I think we can revert this patch.
    > >
    > > I'll wait on the original reporters of the bug to find out. If the clock
    > > does not go backwards when the above commit is applied, then this patch
    > > is not needed.
    > >
    > > If this is the case, do you want me to rebase without it, or should we
    > > just revert it?
    >
    > A revert would be nicer (with an explanation in it), as i've already pushed out the
    > perc/core tree.
    >
    > If you do the revert today against the current perf/core tip (bee96907383e) then i
    > can pull it in a fast-forward way and we'd minimalize the window.

    I've just been informed that even with this patch, the clock still goes
    backwards after resume.

    -- Steve




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