lkml.org 
[lkml]   [2011]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFC][PATCH 1/3] sched, block: Move unplug
    On 2011-06-22 01:34, Peter Zijlstra wrote:
    > Thomas found that we're doing a horrendous amount of work in that scheduler
    > unplug hook while having preempt and IRQs disabled.
    >
    > Move it to the head of schedule() where both preemption and IRQs are enabled
    > such that we don't get these silly long IRQ/preempt disable times.
    >
    > This allows us to remove a lot of special magic in the unplug path,
    > simplifying that code as a bonus.

    The major change here is moving the queue running inline, instead of
    punting to a thread. The worry is/was that we risk blowing the stack if
    something ends up blocking inadvertently further down the call path.
    Since it's the unlikely way to unplug, a bit of latency was acceptable
    to prevent this problem.

    I'm curious why you made that change? It seems orthogonal to the change
    you are actually describing in the commit message.

    --
    Jens Axboe



    \
     
     \ /
      Last update: 2011-06-22 09:03    [W:0.022 / U:30.248 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site