[Xen-users] Pthreads Overhead

Bent Masriya
Fri, 23 Oct 2009 18:59:55 -0000

Hi all,
I have been seeing a considerable (2x-3x) overhead when using Posix pthreads
and pthreads mutux synchronization on Xen dom0. I am not sure if this is an
inherent overhead of Xen or a wrong configuration on my side.

Basically,  I run a simple benchmark to time pthread_create and
pthread_mutex_lock/unlock for 200 threads and the overhead I am measuring
for xen dom0 is  1.5x-2.9x relative to the non-xenified (native)
performance. Can someone please confirm if they have seen similar overhead
and/or shed some light on the source of this overhead

I am using 2.6.26-2-xen-amd64Xen with eight VCPU, and 8 physical cores/ 2
sockets and comparing it to Linux 2.6.18.8 SMP on the same machine.  This is
Xen 3.2 with a credit scheduler. I am seeing this overhead for both HVM and
paravirtualized Xen. Please, advise.


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