lkml.org 
[lkml]   [2013]   [Apr]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH 3/3] mm: when handling percpu_pagelist_fraction, use on_each_cpu() to set percpu pageset fields.
From
On Fri, Apr 5, 2013 at 11:33 PM, Cody P Schafer <cody@linux.vnet.ibm.com> wrote:
> In free_hot_cold_page(), we rely on pcp->batch remaining stable.
> Updating it without being on the cpu owning the percpu pageset
> potentially destroys this stability.
>
> Change for_each_cpu() to on_each_cpu() to fix.

Are you referring to this? -

1329 if (pcp->count >= pcp->high) {
1330 free_pcppages_bulk(zone, pcp->batch, pcp);
1331 pcp->count -= pcp->batch;
1332 }

I'm probably missing the obvious but won't it be simpler to do this in
free_hot_cold_page() -

1329 if (pcp->count >= pcp->high) {
1330 unsigned int batch = ACCESS_ONCE(pcp->batch);
1331 free_pcppages_bulk(zone, batch, pcp);
1332 pcp->count -= batch;
1333 }

Now the batch value used is stable and you don't have to IPI every CPU
in the system just to change a config knob...

Thanks,
Gilad



--
Gilad Ben-Yossef
Chief Coffee Drinker
gilad@benyossef.com
Israel Cell: +972-52-8260388
US Cell: +1-973-8260388
http://benyossef.com

"If you take a class in large-scale robotics, can you end up in a situation
where the homework eats your dog?"
-- Jean-Baptiste Queru


\
 
 \ /
  Last update: 2013-04-08 15:04    [W:0.174 / U:0.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site