lkml.org 
[lkml]   [2006]   [Nov]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [patch] Mark rdtsc as sync only for netburst, not for core2
Date
On Tuesday 28 November 2006 11:28, Arjan van de Ven wrote:
> Hi,
>
> On the Core2 cpus, the rdtsc instruction is not serializing (as defined
> in the architecture reference since rdtsc exists) and due to the deep
> speculation of these cores, it's possible that you can observe time go
> backwards between cores due to this speculation. Since the kernel
> already deals with this with the SYNC_RDTSC flag, the solution is
> simple, only assume that the instruction is serializing on family 15...
>
> The price one pays for this is a slightly slower gettimeofday (by a
> dozen or two cycles), but that increase is quite small to pay for a
> really-going-forward tsc counter.

Added thanks

-Andi
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-11-28 11:45    [W:0.088 / U:0.056 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site