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

Daniel Phillips
2001-08-27T15:58:06Z

On August 27, 2001 05:14 pm, Rik van Riel wrote:
> On Mon, 27 Aug 2001, Alex Bligh - linux-kernel wrote:
>
> > A nit: I think it's a MRU list you want.
>
> Absolutely, however ...
>
> > If you are reading
> > ahead (let's have caps for a page that has been used for reading,
> > as well as read from the disk, and lowercase for read-ahead that
> > has not been used):
> > ABCDefghijklmnopq
> > | |
> > read disk
> > ptr head
> > and you want to reclaim memory, you want to drop (say) 'pq'
> > to get
> > ABCDefghijklmno
> > for two reasons: firstly because 'efg' etc. are most likely
> > to be used NEXT, and secondly because the diskhead is nearer
> > 'pq' when you (inevitably) have to read it again.
>
> This is NOT MRU, since p and q have not been used yet.
> In this example you really want to drop D and C instead.

What we mean by "drop" is "deactivate".

--
Daniel