lkml.org 
[lkml]   [2015]   [Nov]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 3/4] sched: introduce synchronized idle injection
    On Wed, Nov 18, 2015 at 12:27:04PM +0000, Morten Rasmussen wrote:
    > On Wed, Nov 18, 2015 at 11:35:41AM +0100, Peter Zijlstra wrote:
    > > On Wed, Nov 18, 2015 at 09:36:22AM +0100, Ingo Molnar wrote:
    > > > What will such throttling do to latencies, as observed by user-space tasks? What's
    > > > the typical expected frequency of the throttling frequency that you are targeting?
    > >
    > > The default has 5ms (iirc) of forced idle, so depending on what you do,
    > > noticeable to outright painful.
    >
    > IIUC, it is 5 ticks, not ms.

    The code uses hrtimers (badly), this means there _should_ not be a tick
    dependency.

    > Which raises the question, doesn't that mean that we get disturbed four
    > times on each cpu during the forced idle period? So idle injection only
    > makes sense if the platform has package states with a target residency
    > less than a jiffy. Or, do we enter NOHZ idle? I haven't looked closely
    > enough to figure out yet.

    The idea is to hit NOHZ.


    \
     
     \ /
      Last update: 2015-11-18 14:01    [W:2.879 / U:0.192 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site