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[Xen-devel][RFC]degradation on IPF due to hypercall set irq

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: [Xen-devel][RFC]degradation on IPF due to hypercall set irq
From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
Date: Wed, 22 Nov 2006 11:33:49 +0800
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel][RFC]degradation on IPF due to hypercall set irq
Keir,

After moving from sharing PIC to hypercall set irq.
KB on UP VTI domain incurs > 10% degradation.

The root cause is hypercall is very expensive on IPF side
due to huge processor context.

I revert to sharing PIC in lastest Cset of IPF side,
Then We can get performance back.


I prepare to use shared IOSAPIC to deliver interrupt from 
Qemu to VTI domain.
In IPF side, PIC is not needed,
In the same time, we can assign more interrupt pins(24) to qemu.


What's your opinion?


Thanks,
Anthony

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