Re: DMA transfers in 2.5.67

From: Ivan Kokshaysky (ink@jurassic.park.msu.ru)
Date: Wed Apr 16 2003 - 03:36:54 EST


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.

Ivan.
-
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/



This archive was generated by hypermail 2b29 : Wed Apr 23 2003 - 22:00:17 EST