Re: [reiserfs-list] Re: [reiserfs-dev] Re: Note describing poor dcache utilization under high memory pressure

From: Oliver Xymoron (oxymoron@waste.org)
Date: Wed Jan 30 2002 - 02:17:50 EST


On Tue, 29 Jan 2002, Andrew Morton wrote:

> Andreas Dilger wrote:
> >
> > But if it is unused and not recently referenced, there is little benefit
> > in keeping it around, is there?
>
> In all of this, please remember that all caches are not of
> equal value-per-byte. A single page contains 32 dentries,
> and can thus save up to 32 disk seeks. It's potentially
> a *lot* more valuable than a (single-seek) pagecache page.

Or it might equally well be 32 contiguous directory entries that you
scanned over to get to the file you wanted. If it's 32 hot items, as a
page it's going to be aged significantly less than one equally hot
pagecache page, so I don't think we need to worry about that too much.

-- 
 "Love the dolphins," she advised him. "Write by W.A.S.T.E.."

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