[Gluster-devel] Is there any advantage or disadvantage to multiple cpu cores?

Raghavendra Gowdappa rgowdapp at redhat.com
Mon Dec 14 11:27:39 UTC 2015

----- Original Message -----
> From: "Joe Julian" <joe at julianfamily.org>
> To: "Gluster Devel" <gluster-devel at gluster.org>
> Sent: Monday, December 14, 2015 2:40:14 PM
> Subject: [Gluster-devel] Is there any advantage or disadvantage to multiple	cpu cores?
> Does the code take advantage of multiple cpu cores?

On client:
* We've multiple threads to receive replies from bricks parallely (multithreaded epoll).
* the thread that reads from /dev/fuse doesn't generally process replies. So, request and reply processing can happen parallely.

On Bricks:
* io-threads enables parallelism for processing all request/reply parallely.

So, we've multiple threads that can execute on multiple cores simultaneously. However, we've don't really assign threads to cores.

> If I assigned a single core to gluster, would it have an effect on
> performance?

Long time back there was this proposal to make sure a request gets assigned to a thread executing on the same core on which application issued the syscall. The idea was to minimize too many process context switches on a core and thereby conserve relevancy of cpu-cache. But nothing concrete happened towards that goal.

> If yes, explain so I can determine a sane number of cores to allocate
> per server.
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