[Devel] Re: seems to be a flaw in cfq

[Jens Axboe]

On Thu, Dec 21 2006, Vasily Tarasov wrote:
> Jens Axboe wrote:
> > On Thu, Dec 21 2006, Vasily Tarasov wrote:
> >   
> >> Hello,
> >>
> >> On 2.6.19 "buffered randread" bizarre behavior persists. So it was fixed
> >> somewhere in 2.6.20... Can you give me a guess, what changes in 2.6.20
> >> cause this fix? The point is that we want to port it back to 2.6.18
> >> (rhel-5), if possible.
> >>     
> >
> > Is the 2.6.19 buffered randread case a CFQ only problem?
> >   
> Yes, deadline and anticipatory don't have no such problem at all.

My best uneducated guess would be this one:

http://git.kernel.dk/?p=linux-2.6-block.git;a=commit;h=5fccbf61be2a7f32d2002b04afca4c5009612a58

Try and apply that to 2.6.18 and see if that fixes it.

-- 
Jens Axboe