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SubjectRe: [PATCH] Radix-tree pagecache for 2.5

On 1 Feb 2002, Momchil Velikov wrote:

> Ingo> definitely, because in the case of page buckets there are many locks
> Ingo> hashed in a mapping-neutral way. Ie. different parts of the same file will
> Ingo> likely map to different spinlocks.
>
> That's why it's likely to miss on each access.

yes, you are right.

> Ingo> In the radix tree case all pages in the inode will map to the
> Ingo> same spinlock.
>
> That's why it's likely to bounce on each access.
>
> So, is there any difference ? :)

no difference. I tried to create a testcase that shows the difference
(multiple processes read()ing a single big file on an 8-way box), but
performance was equivalent. So given the clear advantages of radix trees
in other areas, they win hands down. :)

Ingo

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