RE: [Xen-devel] unnecessary VCPU migration happens again

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Emmanuel Ackaouy write on 2006年12月14日 6:05:
> Anthony,
> 
> I checked in a change to the scheduler multi-core/thread
> mechanisms in xen-unstable which should address the over
> aggressive migrations you were seeing.
> 
> Can you pull that change, try your experiments again, and
> let me know how it works for you?


Hi Emmanuel,

Sorry for late response,

I did some performances tests based on your patch, SMP VTI Kernel build
and SMP VTI LTP.

Your patch is good, and reduce the majority of unnecessary migrations.
But the unnecessary migration still exist. I can still see about 5% performance
degradation on above benchmark( KB and LTP).
In fact this patch had helped a lot (from 27% to 5%)

I can understand it is impossible to implement spreading VCPU over all 
sockets/cores
and eliminate all unnecessary migration in the same time.

Is it possible for us to add a argument to function scheduler_init to 
enable/disable 
spreading VCPU feature?

It's caller's responsibilty to enable/disable this feature.

BTW, I used attatched patch to disable spreading VCPU feature.



Thanks,
Anthony



> 
> Cheers,
> Emmanuel.
> 
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Attachment: sched.patch
Description: sched.patch

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