From: James Bottomley <James.Bottomley@SteelEye.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Matthew Wilcox <matthew@wil.cx>, Jeremy Higdon <jeremy@sgi.com>,
Grant Grundler <grundler@parisc-linux.org>,
Jesse Barnes <jbarnes@engr.sgi.com>,
Matthew Wilcox <willy@debian.org>,
Andrew Vasquez <andrew.vasquez@qlogic.com>,
pj@sgi.com, SCSI Mailing List <linux-scsi@vger.kernel.org>,
mdr@cthulhu.engr.sgi.com, jeremy@cthulhu.engr.sgi.com,
djh@cthulhu.engr.sgi.com, Andrew Morton <akpm@osdl.org>,
Richard Henderson <rth@twiddle.net>,
Paul Mackerras <paulus@samba.org>
Subject: Re: I/O write ordering
Date: 22 Sep 2004 11:43:37 -0400 [thread overview]
Message-ID: <1095867824.2295.13.camel@mulgrave> (raw)
In-Reply-To: <1095866930.6340.11.camel@gaston>
On Wed, 2004-09-22 at 11:28, Benjamin Herrenschmidt wrote:
> - consistent memory is either cacheable or non-cacheable depending on
> the CPU type (some embedded CPUs who don't implement cache coherency
> will map consistent memory as non-cacheable, most desktop CPUs and all
> 64 bits CPU don't mind and will map it cacheable).
Yes, this was what I feared, since streaming memory has exact ownership
and handoff paradigms for handling it.
Your problem case is consistent memory access vs readX/writeX then.
Could you not just make consistent memory always uncacheable ... then
you'd look identical to everyone else...
The alternative in I/O terms is to implement an ownership model for
consistent PCI memory itself...which is sort of what I had to do in the
dma_noncoherent_alloc() API, but to make that more general would be
quite a bit of work.
James
next prev parent reply other threads:[~2004-09-22 15:44 UTC|newest]
Thread overview: 63+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <B179AE41C1147041AA1121F44614F0B060EF48@AVEXCH02.qlogic.org>
[not found] ` <20040916121235.5e4f9c32.pj@sgi.com>
[not found] ` <1095362263.16326.12.camel@praka>
2004-09-16 19:56 ` SCSI QLA not working on latest *-mm SN2 Paul Jackson
2004-09-16 20:05 ` Jesse Barnes
2004-09-16 20:56 ` Andrew Vasquez
2004-09-16 21:09 ` Jesse Barnes
2004-09-16 21:40 ` Andrew Vasquez
2004-09-16 22:25 ` Andrew Morton
2004-09-16 22:29 ` Jesse Barnes
2004-09-17 17:21 ` Jesse Barnes
2004-09-18 6:10 ` Grant Grundler
2004-09-18 17:57 ` Documentation/io_ordering.txt is wrong Matthew Wilcox
2004-09-20 23:39 ` Jesse Barnes
2004-09-21 0:38 ` Jesse Barnes
2004-09-20 22:40 ` SCSI QLA not working on latest *-mm SN2 Jesse Barnes
2004-09-20 23:27 ` Grant Grundler
2004-09-21 0:09 ` Jesse Barnes
2004-09-21 5:46 ` Grant Grundler
2004-09-21 6:45 ` Jeremy Higdon
2004-09-21 13:29 ` Jesse Barnes
2004-09-21 13:25 ` Jesse Barnes
2004-09-21 15:13 ` Jesse Barnes
2004-09-21 15:41 ` James Bottomley
2004-09-21 15:58 ` Jesse Barnes
2004-09-21 16:01 ` Matthew Wilcox
2004-09-21 16:05 ` Jesse Barnes
2004-09-21 16:11 ` James Bottomley
2004-09-21 16:18 ` Jesse Barnes
2004-09-21 16:24 ` James Bottomley
2004-09-21 17:03 ` Jesse Barnes
2004-09-21 17:15 ` Matthew Wilcox
2004-09-21 17:24 ` Jesse Barnes
2004-09-21 17:20 ` James Bottomley
2004-09-21 17:46 ` Jesse Barnes
2004-09-21 17:56 ` James Bottomley
2004-09-21 18:09 ` Jesse Barnes
2004-09-21 19:06 ` Grant Grundler
2004-09-21 19:40 ` Jesse Barnes
2004-09-21 22:44 ` Grant Grundler
2004-09-21 21:03 ` Jeremy Higdon
2004-09-21 21:11 ` Matthew Wilcox
2004-09-21 21:43 ` Jeremy Higdon
2004-09-21 22:33 ` Jesse Barnes
2004-09-22 0:02 ` Matthew Wilcox
2004-09-22 1:16 ` Jeremy Higdon
2004-09-22 1:44 ` Grant Grundler
2004-09-22 2:58 ` Jeremy Higdon
2004-09-22 14:32 ` I/O write ordering Matthew Wilcox
2004-09-22 14:40 ` Benjamin Herrenschmidt
2004-09-22 14:50 ` Jesse Barnes
2004-09-22 14:47 ` James Bottomley
2004-09-22 14:51 ` Benjamin Herrenschmidt
2004-09-22 15:11 ` James Bottomley
2004-09-22 15:11 ` Benjamin Herrenschmidt
2004-09-22 15:22 ` James Bottomley
2004-09-22 15:28 ` Benjamin Herrenschmidt
2004-09-22 15:43 ` James Bottomley [this message]
2004-09-23 0:19 ` Benjamin Herrenschmidt
2004-09-23 1:58 ` Matthew Wilcox
2004-09-23 3:01 ` James Bottomley
2004-09-23 3:40 ` Benjamin Herrenschmidt
2004-09-23 4:26 ` Grant Grundler
2004-09-21 23:03 ` SCSI QLA not working on latest *-mm SN2 Guennadi Liakhovetski
2004-09-16 23:14 ` Jeremy Higdon
2004-09-16 20:11 ` Andrew Morton
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