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From: Pierre Ossman <drzeus@drzeus•cx>
To: Tejun Heo <htejun@gmail•com>
Cc: "Rafael J. Wysocki" <rjw@sisk•pl>,
	James Bottomley <James.Bottomley@hansenpartnership•com>,
	Stephen Rothwell <sfr@canb•auug.org.au>,
	linux-next@vger•kernel.org, LKML <linux-kernel@vger•kernel.org>,
	Andrew Morton <akpm@linux-foundation•org>,
	Kernel Testers List <kernel-testers@vger•kernel.org>,
	scsi <linux-scsi@vger•kernel.org>,
	Jens Axboe <jens.axboe@oracle•com>,
	linux-ide <linux-ide@vger•kernel.org>,
	Jeff Garzik <jeff@garzik•org>, Takashi Iwai <tiwai@suse•de>,
	tino.keitel@gmx•de
Subject: Re: linux-next: Tree for July 16 (crash on quad core AMD)
Date: Sat, 19 Jul 2008 03:30:50 +0200	[thread overview]
Message-ID: <20080719033050.552f9b49@mjolnir.drzeus.cx> (raw)
In-Reply-To: <48813C5F.70007@gmail.com>

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On Sat, 19 Jul 2008 09:59:11 +0900
Tejun Heo <htejun@gmail•com> wrote:

> Pierre Ossman wrote:
> > I just have one objection to your version, and that is that it cannot
> > be used to nibble away at the sg list. The _next() call jumps an entire
> > page, whereas you sometimes need to consume that page in two different
> > sweeps. This could be handled by some external buffer that keeps the
> > remainder of the page, but the point of these functions was to keep
> > things simple for the callers.
> 
> Well, I don't know how often such usages would be necessary.  If it's a
> very common ops, you can add a param to the next function but frankly I
> think it's better to build a inside control structure for that.  There's
> no need for external buffer, just an inner loop is sufficient.
> 

I'm not sure how this can be solved by an inner loop. My primary use
case is:

1. Wait for interrupt
2. Write n bytes
3. goto 1

n has no guarantee of being aligned to any page boundaries, so state
needs to be kept between each invokation of writing a chunk of data. I
doubt I'm alone in this use pattern (in fact, most device drivers using
PIO should do something similar).

-- 
     -- Pierre Ossman

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  reply	other threads:[~2008-07-19  1:30 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-07-16 13:50 linux-next: Tree for July 16 Stephen Rothwell
2008-07-16 18:15 ` Takashi Iwai
2008-07-16 22:53 ` linux-next: Tree for July 16 (crash on quad core AMD) Rafael J. Wysocki
2008-07-16 23:01   ` James Bottomley
     [not found]     ` <1216249292.3358.66.camel-bi+AKbBUZKY6gyzm1THtWbp2dZbC/Bob@public.gmane.org>
2008-07-16 23:09       ` Rafael J. Wysocki
2008-07-18 12:38         ` Tejun Heo
     [not found]           ` <48808EE0.2060603-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2008-07-18 22:47             ` Pierre Ossman
2008-07-19  0:59               ` Tejun Heo
2008-07-19  1:30                 ` Pierre Ossman [this message]
     [not found]                   ` <20080719033050.552f9b49-OhHrUh4vRMSnewYJFaQfwJ5kstrrjoWp@public.gmane.org>
2008-07-19  2:12                     ` Tejun Heo
2008-07-19 12:07                       ` Pierre Ossman
2008-07-19 14:03                         ` Tejun Heo
2008-07-20 22:40                           ` Pierre Ossman
     [not found]                             ` <20080721004033.1fc66aa3-OhHrUh4vRMSnewYJFaQfwJ5kstrrjoWp@public.gmane.org>
2008-07-21  0:38                               ` Tejun Heo
     [not found]                                 ` <4883DA8C.5030306-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2008-07-21 11:32                                   ` Pierre Ossman
2008-07-21 15:35                                     ` Tejun Heo

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