lkml.org 
[lkml]   [2017]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH 1/2] mm: NUMA stats code cleanup and enhancement
Date
Vlastimil Babka <vbabka@suse.cz> writes:
>
> I'm worried about the "for_each_possible..." approach here and elsewhere
> in the patch as it can be rather excessive compared to the online number
> of cpus (we've seen BIOSes report large numbers of possible CPU's). IIRC

Even if they report a few hundred extra reading some more shared cache lines
is very cheap. The prefetcher usually quickly figures out such a pattern
and reads it all in parallel.

I doubt it will be noticeable, especially not in a slow path
like reading something from proc/sys.

> the general approach with vmstat is to query just online cpu's / nodes,
> and if they go offline, transfer their accumulated stats to some other
> "victim"?

That's very complicated, and unlikely to be worth it.

-Andi

\
 
 \ /
  Last update: 2017-11-28 19:41    [W:0.066 / U:0.156 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site