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    SubjectRe: [PATCH v6 2/2] Output stall data in debugfs
    On Thu, Aug 11, 2011 at 1:23 PM, Peter Zijlstra <> wrote:
    > On Thu, 2011-08-11 at 13:10 -0700, Alex Neronskiy wrote:
    > Ah, right, yeah, stick another lock in there.. One does worry about the
    > whole writer concurrency thing though, isn't it likely all cpus will
    > tickle the thing in quick succession? Putting a global lock in that path
    > isn't good,.. always think of the poor sod with the 4096 cpu machine.
    Is it common to disable interrupts on all 4096 CPU's at once?

    > Also, is all of this really useful? The hardlockup watchdog is useful
    > when you mess up bad, but other than that I've never found it to be
    > useful at all.
    > I mean, we're at the point where a PREEMPT=y kernel has a pretty decent
    > latency and the PREEMPT_RT kernels live at ~30us. So wth are you
    > measuring?
    Well, not all kernels have PREEMPT. Chromebook kernels don't, for example.

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