[Gluster-devel] Setup recommendations - 2 (io-threads)

Raghavendra G raghavendra.hg at gmail.com
Tue Aug 19 03:42:04 UTC 2008

Hi Martin,

On Tue, Aug 19, 2008 at 1:16 AM, Martin Fick <mogulguy at yahoo.com> wrote:

> --- On Thu, 5/15/08, Amar S. Tumballi <amar at zresearch.com> wrote:
> > ''io-threads'' translator creates seperate
> > threads (as specified by the option). But, it doesn't
> > make sense to have more threads than number of CPUs
> > available. It works good if the thread
> > count is same as number of CPUs you have in server.
> Could you please explain the reasoning behind this statement?
> Wouldn't adding multiple threads on a single CPU server still
> allow a server thread to potentially serve files to other
> clients while it is blocked serving one client?

Couple of points to be noted are,

* Apart from the io-threads, there is a separate fuse thread which
reads/writes to /dev/fuse.
* Since glusterfs operates in asynchronous framework, potentially there are
very less scenarios, where a thread can block.

Hence the purpose of io-threads is only for simultaneous executions. And the
number of simultaneous execution paths is determined by the number of
processors present.

Can anyone confirm this?

> -Martin
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Raghavendra G

A centipede was happy quite, until a toad in fun,
Said, "Prey, which leg comes after which?",
This raised his doubts to such a pitch,
He fell flat into the ditch,
Not knowing how to run.

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