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    SubjectRe: [PATCH] timers/nohz: Update nohz load even if tick already stopped
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    On Tue, 2019-11-05 at 13:43 +0100, Peter Zijlstra wrote:
    > On Tue, Nov 05, 2019 at 01:30:58AM -0600, Scott Wood wrote:
    > > As for the warning in sched_tick_remote(), it seems like a test for time
    > > since the last tick on this cpu (remote or otherwise) would be better
    > > than
    > > relying on curr->se.exec_start, in order to detect things like this.
    >
    > I don't think we have a timestamp that is shared between the remote and
    > local tick.

    Why wouldn't rq_clock_task() work on the local tick? It's what
    ->task_tick() itself uses.

    > Also, there is a reason this warning uses the task time
    > accounting, there used to be (as in, I can't find it in a hurry) code
    > that could not deal with >u32 (~4s) clock updates.

    Detecting a 3 second interval between ticks for a given cpu should assert in
    a superset of the situations the current check asserts in -- it just avoids
    the false negative of exec_runtime getting updated by something other than
    the tick.

    -Scott


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