From: Christoph Hellwig <hch@infradead.org>
To: James Bottomley <James.Bottomley@SteelEye.com>
Cc: Mark Haverkamp <markh@osdl.org>,
linux-scsi <linux-scsi@vger.kernel.org>,
Mark Salyzyn <mark_salyzyn@adaptec.com>
Subject: Re: [PATCH 3/5] aacraid: update dma mapping
Date: Wed, 30 Nov 2005 18:49:51 +0000 [thread overview]
Message-ID: <20051130184951.GA18583@infradead.org> (raw)
In-Reply-To: <1133376327.3312.43.camel@mulgrave>
On Wed, Nov 30, 2005 at 12:45:27PM -0600, James Bottomley wrote:
> On Wed, 2005-11-30 at 10:36 -0800, Mark Haverkamp wrote:
> > This patch changes map_single to map_page in compliance with
> > recommendations made in the IO-Perf howto document to prevent bounce
> > buffering of DMA requests.
>
> Erm, there's a misunderstanding somewhere. You're replacing correct
> pci_map_single calls with its more difficult to use pci_map_page. This
> has absolutely zero performance impact and adds the risk that because
> pci_map_page is more complex to use, someone gets it wrong somewhere.
> Really, for block devices pci_map_single is the absolutely correct
> interface. pci_map_page should really only be used by the net stack for
> packet fragment mapping.
And the really nice thing is that this whole non-S/G I/O path will go away
completely for 2.6.16 :)
next prev parent reply other threads:[~2005-11-30 18:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-11-30 18:36 [PATCH 3/5] aacraid: update dma mapping Mark Haverkamp
2005-11-30 18:45 ` James Bottomley
2005-11-30 18:49 ` Christoph Hellwig [this message]
2005-11-30 18:55 ` Mark Haverkamp
-- strict thread matches above, loose matches on Subject: below --
2005-11-30 19:23 Salyzyn, Mark
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20051130184951.GA18583@infradead.org \
--to=hch@infradead.org \
--cc=James.Bottomley@SteelEye.com \
--cc=linux-scsi@vger.kernel.org \
--cc=mark_salyzyn@adaptec.com \
--cc=markh@osdl.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.