Re: [PATCH] 2.4.20-rmap15a

[Jens Axboe <axboe@suse.de>]

On Mon, Dec 02 2002, Andrew Morton wrote:
> Jens Axboe wrote:
> > 
> > On Sun, Dec 01 2002, Rik van Riel wrote:
> > > > So, here my patch proposal. Ontop of 2.4.20-rmap15a.
> > >
> > > Looks good, now lets test it.  If the patch is as needed as you
> > > say we should push it to marcelo ;)
> > 
> > Yes lets for heavens sake not fix the problem, merge the hack.
> 
> If it fails to find a merge or insert the current 2.4 elevator
> will stick a read at the far end of the request queue.  That's
> quite arbitrary, and is the worst possible thing to do with it.
> 
> read-latency2 will put the read a tunable distance from the head.
> Add a few embellishments to avoid permanent writer starvation,
> and that's basically all it does.

I just think that the design of the thing is ugly. It's clamped on to
the current elevator instead of redoing the core based on the principles
of read-starvation that it introduces (this is the only good thing that
has come out of the patch).

> So rather than just keeping on calling it a "hack" could you please
> describe what is actually wrong with the idea?

I've never said that the idea is wrong, it's the solution that is an
ugly hack.

-- 
Jens Axboe