lkml.org 
[lkml]   [2009]   [Jul]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 1/2] vmscan don't isolate too many pages
KOSAKI Motohiro wrote:

> FAQ
> -------
> Q: Why do you compared zone accumulate pages, not individual zone pages?
> A: If we check individual zone, #-of-reclaimer is restricted by smallest zone.
> it mean decreasing the performance of the system having small dma zone.

That is a clever solution! I was playing around a bit with
doing it on a per-zone basis. Your idea is much nicer.

However, I can see one potential problem with your patch:

+ nr_inactive += zone_page_state(zone, NR_INACTIVE_ANON);
+ nr_inactive += zone_page_state(zone, NR_INACTIVE_FILE);
+ nr_isolated += zone_page_state(zone, NR_ISOLATED_ANON);
+ nr_isolated += zone_page_state(zone, NR_ISOLATED_FILE);
+ }
+
+ return nr_isolated > nr_inactive;

What if we ran out of swap space, or are not scanning the
anon list at all for some reason?

It is possible that there are no inactive_file pages left,
with all file pages already isolated, and your function
still letting reclaimers through.

This means you could still get a spurious OOM.

I guess I should mail out my (ugly) approach, so we can
compare the two :)


\
 
 \ /
  Last update: 2009-07-07 21:03    [W:0.104 / U:0.704 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site