lkml.org 
[lkml]   [2015]   [Dec]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFCv6 PATCH 09/10] sched: deadline: use deadline bandwidth in scale_rt_capacity
On Tue, Dec 15, 2015 at 09:50:14AM +0100, Luca Abeni wrote:
> On 12/15/2015 05:59 AM, Vincent Guittot wrote:

> >The 2nd definition is used to compute the remaining capacity for the
> >CFS scheduler. This one doesn't need to be updated at each wake/sleep
> >of a deadline task but should reflect the capacity used by deadline in
> >a larger time scale. The latter will be used by the CFS scheduler at
> >the periodic load balance pace

> Ok, so as I wrote above this really looks like an average utilisation.
> My impression (but I do not know the CFS code too much) is that the mainline
> kernel is currently doing the right thing to compute it, so maybe there is no
> need to change the current code in this regard.
> If the current code is not acceptable for some reason, an alternative would
> be to measure the active utilisation for frequency scaling, and then apply a
> low-pass filter to it for CFS.

So CFS really only needs a 'vague' average idea on how much time it will
not get. Its best effort etc., so being a little wrong isn't a problem.

The current code suffices, but I think the reason its been changed in
this series is that they want/need separate tracking for fifo/rr and
deadline in the next patch, and taking out deadline like proposed was
the easiest way of achieving that.




\
 
 \ /
  Last update: 2015-12-15 13:41    [W:0.142 / U:0.240 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site