[Gluster-devel] lookup caching

[Raghavendra G]

On Thu, Apr 8, 2010 at 1:21 AM, Olivier Le Cam <
Olivier.LeCam at crdp.ac-versailles.fr> wrote:

> Olivier Le Cam wrote:
>
>> Hi -
>>
>> Apologize for my insistance, but would it be possible to help on the stats
>> caching? This seriously decreases performances with small files readings!
>>
>> I am volunteer to try to deal with stats caching by myself but I would
>> appreciate some guidance in order to know where I could interact in the code
>> for.
>>
>
> Well, as far as I understand the problem is rather that folders on the path
> of the targeted file are not cached at all by io-cache.


Did you mean caching dentries, when you said "caching directories"? io-cache
only caches file data. Also note that it is not a translator which does
metadata (stats) caching.

This is why accessing a file makes (quite a lot) network traffic and can
> introduce bottlenecks because each folder is stated on the servers before
> delivering the file, even if that file is indeed cached by io-cache.
>

io-cache only sends stat on the file being read not to all of its parent
directories. I am not getting the reason you are concerned with too many
stat calls. io-cache (during read and when file is cached) only sends a
single stat call and that too if "cache-timeout" number of seconds have been
elapsed since last validation.


> I'm still trying to figure out how I can get this cached as well and will
> appreciate any pointers.
>
>
> Thanks and best regards,
> --
> Olivier
>
>
>
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-- 
Raghavendra G
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