[Gluster-devel] how to measuere the effectiveness of io-cache?

[Anand Avati]

> thanks, that sounds like "wow, when will it be there?" :-)
>
> my I add another question: do the caches communitcate with each other?
> that
> is, how does the cache on client A know that a file was just
> changed/deleted/overwritten by client B, that is, became "dirty"?


by checking mtime. Whenever io-cache gets a chance (any call which is
returning mtime of the file) it validates the cache for a configurable time.
you can set the cache time to be 0 so that every read is verified for cache
validity by an mtime check. if you load read-ahead over io-cache, this
verification overhead is reduced since a single stat call is done for
pipelined verifications.

avati


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