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From: "Jaya Kumar" <jayakumar.lkml@gmail.com>
To: "Paul Mundt" <lethal@linux-sh.org>,
	"Jaya Kumar" <jayakumar.lkml@gmail.com>,
	"Peter Zijlstra" <a.p.zijlstra@chello.nl>,
	linux-fbdev-devel@lists.sourceforge.net,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	jsimmons@infradead.org, Geert.Uytterhoeven@sonycom.com
Subject: Re: [PATCH 2.6.20 1/1] fbdev,mm: hecuba/E-Ink fbdev driver
Date: Wed, 21 Feb 2007 11:46:21 -0500	[thread overview]
Message-ID: <45a44e480702210846u218045bmfe6854fb894d7bbd@mail.gmail.com> (raw)
In-Reply-To: <45a44e480702192211i78b8f4b1lecb3dfc284fb9eea@mail.gmail.com>

On 2/20/07, Jaya Kumar <jayakumar.lkml@gmail.com> wrote:
> On 2/19/07, Paul Mundt <lethal@linux-sh.org> wrote:
> > That works for me, though I'd prefer for struct page_list to be done with
> > a scatterlist, then it's trivial to setup from the workqueue context
> > without having to shuffle things around.
> >
>
> Ok. Will check out when implementing.
>

Took  a quick look. If I used scatterlist, I'd still need to build a
list of scatterlist to pass to the driver callback. The alternative
being a preallocated array of scatterlist based on the page count of
the framebuffer, which seems expensive since scatterlist has page,
offset, dma and length.

On a separate note, Peter pointed out that it may be possible to reuse
page->lru instead of using a struct page_list. This would enable
something like:

in mkwrite:
mutex_lock
list_add(page->lru, defio->pagelist)
mutex_unlock

in deferred handler:
mutex_lock
for_each page {
lock_page
mkclean
unlock_page
}
callback(fb_info, pagelist)
for_each page {
list_del
}
mutex_unlock

The advantage of reusing page->lru is that avoids needing the struct
page_list and allocation in mkwrite. Is the above exploitation of
->lru ok with mm folk?

In above, we're iterating over the page list twice. I have to mkclean
before calling the callback to avoid the situation where a touched
page is missed by the callback. I don't see a way around that part.

Thanks,
jaya

  reply	other threads:[~2007-02-21 16:46 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-17 10:42 Jaya Kumar
2007-02-17 12:34 ` Peter Zijlstra
2007-02-17 13:25   ` Jaya Kumar
2007-02-17 13:59     ` Paul Mundt
2007-02-18 11:31       ` Jaya Kumar
2007-02-18 23:57         ` Paul Mundt
2007-02-20  4:13           ` Jaya Kumar
2007-02-20  4:38             ` Paul Mundt
2007-02-20  6:11               ` Jaya Kumar
2007-02-21 16:46                 ` Jaya Kumar [this message]
2007-02-20  8:07             ` Geert Uytterhoeven
2007-02-21 16:55               ` Jaya Kumar
2007-02-21 21:52                 ` James Simmons
2007-02-21 23:22                   ` Jaya Kumar
2007-02-28 16:50                     ` [Linux-fbdev-devel] [PATCH 2.6.20 1/1] fbdev, mm: " James Simmons
2007-02-21 23:43                 ` Antonino A. Daplas
2007-02-21 23:47                   ` Jaya Kumar
2007-02-21 23:43             ` Antonino A. Daplas

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