lkml.org 
[lkml]   [2010]   [Jun]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 1/4, v2] x86: enlightenment for ticket spin locks - base implementation
>>> On 30.06.10 at 14:53, Jeremy Fitzhardinge <jeremy@goop.org> wrote:
> On 06/30/2010 01:52 PM, Jan Beulich wrote:
>> I fail to see that: Depending on the hypervisor's capabilities, the
>> two main functions could be much smaller (potentially there wouldn't
>> even be a need for the unlock hook in some cases),
>
> What mechanism are you envisaging in that case?

A simple yield is better than not doing anything at all.

>> The list really juts is needed to not pointlessly tickle CPUs that
>> won't own the just released lock next anyway (or would own
>> it, but meanwhile went for another one where they also decided
>> to go into polling mode).
>
> Did you measure that it was a particularly common case which was worth
> optimising for?

I didn't measure this particular case. But since the main problem
with ticket locks is when (host) CPUs are overcommitted, it
certainly is a bad idea to create even more load on the host than
there already is (the more that these are bursts).

Jan



\
 
 \ /
  Last update: 2010-06-30 15:23    [from the cache]
©2003-2014 Jasper Spaans. Advertise on this site