On Sun, Jan 06 2002, Davide Libenzi wrote:
> > Davide,
> >
> > If this is caused by ISA bounce problems, then you should be able to
> > reproduce by doing something ala
> >
> > [ drivers/ide/ide-dma.c ]
> >
> > ide_toggle_bounce()
> > {
> > ...
> >
> > + addr = BLK_BOUNCE_ISA;
> > blk_queue_bounce_limit(&drive->queue, addr);
> > }
> >
> > pseudo-diff, just add the addr = line. Now compare performance with and
> > without your scheduler changes.
>
> I fail to understand where the scheduler code can influence this.
> There's basically nothing inside blk_queue_bounce_limit()
Eh of course not, no time will be spent inside blk_queue_bounce_limit. I
don't think you looked very long at this :-)
The point is that ISA bouncing will spend some time scheduling waiting
for available memory in the __GFP_DMA zone.
-- Jens Axboe- 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 : Mon Jan 07 2002 - 21:00:33 EST