Re: [resent PATCH] Re: very slow parallel read performance

Daniel Phillips
2001-08-26T05:26:15Z

On August 26, 2001 05:40 am, Rik van Riel wrote:
> On Sat, 25 Aug 2001, John Stoffel wrote:
>
> > Ummm... is this really more of an agreement that Daniel's used-once
> > patch is a good idea on a system. Keep a page around if it's used
> > once, but drop it quickly if only used once?
>
> There's a very big difference, though. With use-once we'll
> also quickly drop the pages we have not yet used, that is,
> the pages we _are about to use_.

You're really complaining about the treatment of readahead pages, not the
used-once pages. We can arrange things so that readahead pages get higher
priority than used-once pages, then become used-once pages when... they get
used once. Simple idea, but not a one-line implementation.

> Drop-behind specifically drops the pages we have already
> used, giving better protection to the pages we are about
> to use.
>
> http://linux-mm.org/wiki/moin.cgi/StreamingIo

How will you know not to drop the pages of that header file that is used
constantly by the compiler?

--
Daniel