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Re: [libvirt] [PATCH v2] Remove qemuDriverLock from almost everywhere



On Mon, Feb 11, 2013 at 04:47:29PM +0000, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange redhat com>
> 
> With the majority of fields in the virQEMUDriverPtr struct
> now immutable or self-locking, there is no need for practically
> any methods to be using the QEMU driver lock. Only a handful
> of helper APIs in qemu_conf.c now need it

BTW, example of the performance improvements this brings

With the 0.10.2 release of libvirt, running 4 threads in
parallel, each starting + stopping 50 VMs, takes 2 mins 11
seconds.

This is on a 2 CPU machine. I'd expect the win to be even
greater on a machine with more CPUs.


In terms of testing, I am using a torture test which runs
multiple threads, each creating+destroying VMs in parallel.
I've successfully run this for over 5000 VM create+delete
pairs so far, without any issues (it has previously detected
a few crashes and deadlocks during my earlier testing of
previous versions of this patch).

Daniel
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