lkml.org 
[lkml]   [2005]   [May]   [30]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
DateMon, 30 May 2005 10:55:17 +0100
From P@draigBra ...
SubjectRe: The values of gettimeofday() jumps.
Liangchen Zheng wrote:
> Hello,
> 	We have several SMP machines (Tyan Tiger MPX motherboard, 2
> AthlonMP 1900+ CPU, linux-2.4.21-20.EL).  When running some time
> sensitive programs, I observed that the values of gettimeofday() jumped
> sometimes on a couple of machines (other machines are fine), from
> several hundreds milliseconds to a couple of seconds.

That sounds like what I described here:
http://lkml.org/lkml/2005/4/4/57

2 options as far as I can see.

1. Use irq affinity to bind the timer irq to a particular CPU,
    while using CPU affinity to bind your process to a particular CPU.

2. Change the code to maintain a last_tsc_low for each CPU.

-- 
Pádraig Brady - http://www.pixelbeat.org
--
-
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: 2005-05-30 12:01    [from the cache]
©2003-2008