Re: 2.4.20: Proccess stuck in __lock_page ...

[Andrew Morton]

Andrea Arcangeli <[e-mail]> wrote:
>
> On Tue, May 27, 2003 at 03:18:30PM -0700, Andrew Morton wrote:
> > Andrea Arcangeli <[e-mail]> wrote:
> > >
> > > However the last numbers from Randy showed my tree going faster than 2.5
> > > with bonnie and tiotest so I think we don't need to worry and I would
> > > probably not fix it in a different way in 2.4 even if it would mean a 1%
> > > degradation.
> > 
> > That could be because -aa quadruples the size of the VM readahead window.
> > 
> > Changes such as that should be removed when assessing the performance
> > impact of this particular patch.
> 
> I understand that was a generic benchmark against 2.5, not meant to
> evaluate the effect of the fixed readahead (see the name of the patch
> "readahead-got-broken-somehwere"). I don't see any good reason why
> should Randy cripple down my tree before benchmarking against 2.5? if
> something it's ok to apply some of my patches to 2.5, that's great, the
> other way around not IMHO.
> 

No.

What I am saying is that evaluation of the effect of an IO scheduler change
cannot be performed when there is a 4:1 change in the readhead window present
in the same tree.

ie: we cannot conclude anything about the effect of the IO scheduler change
from Randy's numbers.  Too many variables.