Re: "fb-defio: fix page list with concurrent processes"

From: Jaya Kumar
Date: Tue Jun 17 2008 - 04:21:44 EST


On Tue, Jun 17, 2008 at 12:34 AM, Markus Armbruster <armbru@xxxxxxxxxx> wrote:
> "Jaya Kumar" <jayakumar.lkml@xxxxxxxxx> writes:
>
>> On Mon, Jun 16, 2008 at 3:05 PM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>>> Your patch "fb-defio: fix page list with concurrent processes" definitely
>>> seems to help with the suspend/resume problem I had with the Xen pvfb
>>> device. Is it queued up anywhere? It seems to be a real bugfix, and should
>>> probably be queued for 2.6.26...
>>
>> It isn't currently queued. I had intended to improve its performance
>> by taking advantage of Andrew's suggestion of using !list_empty on the
>> page->lru to avoid walking the page list to find the duplicate page,
>> but I ran into trouble since the page starts off being on the lru
>> list. I'll try to take a look at doing this next weekend.
>>
>> Thanks,
>> jaya
>
> Well, we got a bug that makes the code useless in practice for us, and
> a fix for it that's not quite as fast as it could be. Which is
> better, somewhat slow code, or somewhat useless code? I'd like to see
> the fix merged as soon as possible. You can always improve its
> performance later.
>

Ok, I didn't realize there was any time pressure. Keep in mind, I'm
just a person doing this stuff for fun on weekends not someone under
commercial pressures. Yup, I've got no problem if the old patch is
requeued and merged.

Thanks,
jaya
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