lkml.org 
[lkml]   [2003]   [Apr]   [16]   [last100]   RSS Feed
Views: [more markup]  [less markup]  [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: DMA transfers in 2.5.67
From(Måns_Rullgård)
Date16 Apr 2003 10:43:47 +0200
Ivan Kokshaysky <ink@jurassic.park.msu.ru> writes:

> On Wed, Apr 16, 2003 at 12:09:00AM +0200, Måns Rullgård wrote:
> > Btw, I just noticed that hard disk throughput is much lower with 2.5
> > than 2.4.  With 2.4.21-pre5 I get ~40 MB/s, but with 2.5.67 the speed
> > drops to 25-30 MB/s.  Everything according to hdparm.  Is it possible
> > that DMA is generally slow for some reason?
> 
> Possible reason is that in 2.4 we've forced reasonable latency timer
> value for all PCI devices, while in 2.5 we haven't as yet.

Do you mean whatever causes this message (for a 3com NIC)?

PCI: Setting latency timer of device 00:05.0 to 64

Would that also explain why my hard disks are slow under 2.5?  There
is no corresponding message for the ide controller (htp374).

-- 
Måns Rullgård
mru@users.sf.net
-
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: 2005-03-22 12:34    [from the cache]
©2003-2008