Re: Linux v2.4.19-rc5

Jens Axboe (axboe@suse.de)
Thu, 1 Aug 2002 10:10:10 +0200

On Thu, Aug 01 2002, Marcelo Tosatti wrote:
>
> On Thu, 1 Aug 2002, Jens Axboe wrote:
>
> > On Thu, Aug 01 2002, Marcelo Tosatti wrote:
> > > <akpm@zip.com.au> (02/08/01 1.663)
> > > [PATCH] disable READA
> >
> > Since -rc5 is not to be found yet, I don't know what version of this
> > made it in. Is READA just being disabled on SMP, or was it the general
> > #if 0 change that got included?
>
> Its being disabled on UP and SMP. I dont like having such readahead IO
> mode working only for UP.

You are right, that would be ugly. Should only be the last resort.

> > I'm asking since plain disabling READA might have nasty performance
> > effects. Andrew, I bet you did some numbers on this, care to share?
>
> If thats true (the performance effects) I'll release -final with IMO not
> very coherent READA semantics :)
>
> Anyway, lets wait for the numbers.

It just 'feels' like the sort of change that might have odd side
effects.

-- 
Jens Axboe


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