Re: [PATCH] speed up SATA

[Jens Axboe]

On Mon, Mar 29 2004, Arjan van de Ven wrote:
> On Mon, 2004-03-29 at 14:44, Jens Axboe wrote:
> > On Mon, Mar 29 2004, Jamie Lokier wrote:
> > > Jens Axboe wrote:
> > > > Could be used to limit tcq depth, not just request sizes solving two
> > > > problems at once. I already have a tiny bit of keeping this
> > > > accounting to do proper unplugs (right now it just looks at missing
> > > > requests from the pool, doesn't work on tcq).
> > > 
> > > Does it make sense to allow different numbers of outstanding TCQ-reads
> > > and TCQ-writes?
> > 
> > Might not be a silly thing to experiment with, definitely something that
> > should be tested (added to list...)
> 
> I wonder if the max read size could/should be correlated with the
> readahead size for such devices... it sounds like a related property at
> least.

Indeed, it would be best to keep the read-ahead window at least a
multiple of the max read size. So you don't get the nasty effects of
having a 128k read-ahead window, but device with 255 sector limit
resulting in 124KB + 4KB read.

-- 
Jens Axboe

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