lkml.org 
[lkml]   [2014]   [May]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: vmstat: On demand vmstat workers V5
On Mon, 12 May 2014, Christoph Lameter wrote:

>
> V4->V5:
> - Shepherd thread on a specific cpu (HOUSEKEEPING_CPU).

That's going to fail for the NOHZ_IDLE case, e.g. for the little/big
cluster support on ARM. They need to be able to move it from the
housekeeper on the big to the housekeeper on the little cluster.

So as I said before: This wants to be on a dedicated housekeeper
workqueue. Where the thread is placed is decided by the core depending
on system configuration and state.

nohz = off CPU0
nohz = idle core decision depending on state
nohz = full CPU0

Your solution solves only the off and full case and will fail when in
the idle case CPU0 should be sent into deep idle sleep until the user
decides to do some work which requires CPU0 to come back.

Thanks,

tglx


\
 
 \ /
  Last update: 2014-05-13 18:01    [W:0.108 / U:0.920 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site