Re: [PATCH 1/1 2.6.25] fbdev: bugfix for multiprocess defio

On Mon, May 5, 2008 at 3:23 AM, Jaya Kumar [off-list ref] wrote:

On Wed, Apr 30, 2008 at 1:37 PM, Andrew Morton
[off-list ref] wrote:

quoted

On Sun, 27 Apr 2008 22:01:40 -0400
 Jaya Kumar [off-list ref] wrote:

 > +     /* we loop through the pagelist before adding in order
 > +     to keep the pagelist sorted */
 > +     list_for_each_entry(cur, &fbdefio->pagelist, lru) {

 Did you consider using !list_empty(&page->lru) to avoid the linear search?

Ah, no, I didn't think of that. I agree that checking list_empty would
be far better. I'll redo the patch using that.

Thanks,
jaya

Hi Andrew,

I encountered some complexity when trying to use page->lru because its
not empty on its first mkwrite. I think there are probably deeper
issues that repurposing page->lru for use in defio causes. I'm working
on it.

In the meantime, it turns out that suspend/resume of xen pvfb is
affected by the same bug that raised this patch. Markus suggested,
http://marc.info/?l=linux-kernel&m=121368814027583&w=2 , that perhaps
this existing patch could be merged in the interim while a better
solution is worked on.

Would you be okay with adding this patch back into the queue? If so,
should I repost it here?

Thanks,
jaya

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