Messages in this thread Patch in this message | | | Date | Wed, 1 Feb 2006 11:34:18 +0100 | From | Bartlomiej Zolnierkiewicz <> | Subject | Re: [patch] SGIIOC4 limit request size |
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On 01 Feb 2006 03:59:16 -0500, Jes Sorensen <jes@sgi.com> wrote: > Hi,
Hi,
> This one takes care of a problem with the SGI IOC4 driver where it > hits DMA problems if the request grows too large.
Does this happen only for CONFIG_IA64_PAGE_SIZE_4KB=y or CONFIG_IA64_PAGE_SIZE_8KB=y?
from sgiioc4.c:
/* Each Physical Region Descriptor Entry size is 16 bytes (2 * 64 bits) */ /* IOC4 has only 1 IDE channel */ #define IOC4_PRD_BYTES 16 #define IOC4_PRD_ENTRIES (PAGE_SIZE /(4*IOC4_PRD_BYTES))
As limiting request size to 127 sectors punishes performance wouldn't it be better to define IOC4_PRD_ENTRIES to 256 if this is possible (would need 4 pages for PAGE_SIZE=4096 and 2 for PAGE_SIZE=8192)?
Cheers. Bartlomiej
> Cheers, > Jes > > Avoid requests larger than the number of SG table entries, to avoid > DMA timeouts. > > Signed-off-by: Jes Sorensen <jes@sgi.com> > > ---- > > drivers/ide/pci/sgiioc4.c | 8 +++++++- > 1 files changed, 7 insertions(+), 1 deletion(-) > > Index: linux-2.6/drivers/ide/pci/sgiioc4.c > =================================================================== > --- linux-2.6.orig/drivers/ide/pci/sgiioc4.c > +++ linux-2.6/drivers/ide/pci/sgiioc4.c > @@ -1,5 +1,5 @@ > /* > - * Copyright (c) 2003 Silicon Graphics, Inc. All Rights Reserved. > + * Copyright (C) 2003, 2006 Silicon Graphics, Inc. All Rights Reserved. > * > * This program is free software; you can redistribute it and/or modify it > * under the terms of version 2 of the GNU General Public License > @@ -613,6 +613,12 @@ > hwif->ide_dma_lostirq = &sgiioc4_ide_dma_lostirq; > hwif->ide_dma_timeout = &__ide_dma_timeout; > hwif->INB = &sgiioc4_INB; > + > + /* > + * Limit the request size to avoid DMA timeouts when > + * requesting more entries than goes in the sg table. > + */ > + hwif->rqsize = 127; > } > > static int __devinit - 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/
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