lkml.org 
[lkml]   [2014]   [May]   [18]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH] x86/mce: Distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU
From
Date
On Sun, 2014-05-18 at 18:35 +0200, Borislav Petkov wrote:
> On Sun, May 18, 2014 at 11:05:04PM +0800, Chen Yucong wrote:a
> > mces_seen is a Per-CPU variable which should only be accessed by
> > Per-CPU as possible. So the clear operation of mces_seen should also
> > be lcoal to Per-CPU rather than monarch CPU.
>
> No, you need to do the cleaning in mce_reign because the monarch cpu has
> to run last after all other cpus have scanned their mce banks.
>
But all other CPUs also have to wait monarch CPU to exit from mce_end.
What's the difference between monarch CPU and Per-CPU for clearing
mces_seen? In practice, there is no difference between them. If we use
monarch CPU to clear mces_seen, then Per-CPU variable can not play out
its advantage.

> > Meanwhile, there is also a potential risk that mces_seen will not
> > be be cleared if a timeout occors in mce_end for monarch CPU. As a
> > reuslt, the stale value of mces_seen will reappear on the next mce.
>
> If that happens, we have a bigger problem.
Well, in that case, why is there a need for time-out machine in MCE
handler?

Any potential risks --both logical and realistic-- should be avoided as
possible if there are no more questions and performance penalty.

thx!
cyc
>
> Is that a real issue you're trying to address?





\
 
 \ /
  Last update: 2014-05-19 04:41    [W:0.072 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site