Since the release of NetBSD 5.0, it is said that the work of Doran Andrew concerning SMP in the NetBSD kernel has improve drastically performance for multi-threaded and/or multi-core processors.

Assuming my server has a multi-core processor, I want to know if this work has an (good) impact when using NetBSD as Dom0 ? as DomU ?

MySQL Benchmark, 8 core Xeon

  • I think when used in Dom0, it is the Xen "kernel" which make the scheduler. But in DomU (with more than 1 vcpu) is there any increase of performance ? – Kortex786 Oct 14 '09 at 4:36

According to the release notes...

NetBSD 5.0 features greatly improved performance and scalability on modern multiprocessor (SMP) and multi-core systems. Multi-threaded applications can now efficiently make use of more than one CPU or core, and system performance is much better under I/O and network load.

I know that 5.0 went from giant lock to fine-grained locking, and also to a 1:1 thread:process model. These will make SMP much faster on bare hardware. There doesn't seem to be any released information w.r.t SMP on the Xen port specifically. It does look like they have the framework to do a good job in the long run.


I don't believe it affects Xen at all. Xen itself is multi-core capable, but as far as I know the NetBSD dom0 and domU kernels are not SMP capable yet.

So, currently, no performance gain, but no loss either.

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