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

Anand Avati avati at zresearch.com
Fri Jan 4 16:14:20 UTC 2008

> 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.


If I traveled to the end of the rainbow
As Dame Fortune did intend,
Murphy would be there to tell me
The pot's at the other end.

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