[OpenAFS] cpu affinity( was: Afs User volume servers in VM's)

Jason Edgecombe jason@rampaginggeek.com
Wed, 26 Oct 2011 15:03:02 -0400


On 10/26/2011 01:03 PM, Andrew Deason wrote:
> On Wed, 26 Oct 2011 12:45:07 -0400
> Jeffrey Altman<jaltman@secure-endpoints.com>  wrote:
>
>>> I wonder why 128 threads (or 256 with 1.6) can't make use of more
>>> than four cores though?
>> Resource contention between threads executing on separate sockets is
>> extremely expensive and there is no practical method of enforcing
>> processor affinity for all of the file server threads to ensure that
>> they only execute on cores within a single socket.  At least not that
>> I am aware of on Linux.  Windows would make such thread execution
>> restrictions trivial.
> Linux, Solaris, and AIX all have this ability; I assume other Unix
> platforms do, as well.
>
Is this what is being asked about?
http://linux.die.net/man/2/sched_setaffinity

On a (single socket)  quad-core box with hyperthreading, is there an 
advantage to restricting the fileserver to use fewer cores?

Thanks,
Jason