Re: [PATCH 02/18] xstat: Add a pair of system calls to make extended file stats available [ver #6]

From: David Howells
Date: Sat Jul 31 2010 - 15:27:49 EST


utz lehmann <lkml123@xxxxxxxxxx> wrote:

> How does this works right with noatime or relatime (which is default)?

Don't do that then.

> We had used FS-Cache with a few 10000s files cached. Doesn't it mean
> that the cleanup has to stat them all?

Yes.

> Why didn't cachefilesd managed the cache index in a separate database
> like other caches?

Because using atime is much simpler since the filesystem updates it
automatically. If you have a separate database then you have redundant
information and you need to maintain metadata integrity which has a cost, both
in terms of disk usage and performance. I'm working on it, but you don't get
it for free.

David
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