[Gluster-users] Concurrency limitation?

[Brian Candler]

On Tue, Feb 07, 2012 at 08:18:24AM -0600, Greg Swift wrote:
>    concurrency will be affected by your underlying filesystem as well.
>    which filesystem you got?

XFS. But as I said, I am comparing direct-to-filesystem versus
via-gluster-to-same-filesystem.

I have been digging through source code. If I am reading it right, it seems
that xlators/performance/io-threads only sets the number of threads to be
log(base2) of the number of outstanding I/O entries in the queue.  That is,
to get 8 concurrent threads you need 256 outstanding requests in the queue.

This doesn't seem right to me. The default limit is 16 threads, but you'd
need 64K+ outstanding queued operations to ever hit that.  I will try
playing with the code a bit.

Regards,

Brian.