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xen-devel
Re: [Xen-devel] Performance overhead of paravirt_ops on nativeidentifie
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To: |
Jan Beulich <JBeulich@xxxxxxxxxx> |
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Subject: |
Re: [Xen-devel] Performance overhead of paravirt_ops on nativeidentified |
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From: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
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Date: |
Thu, 14 May 2009 10:45:31 -0700 |
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Cc: |
Nick Piggin <npiggin@xxxxxxx>, Xiaohui Xin <xiaohui.xin@xxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Xin Li <xin.li@xxxxxxxxx>, Jun Nakajima <jun.nakajima@xxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx> |
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Thu, 14 May 2009 10:46:26 -0700 |
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Jan Beulich wrote:
Wouldn't a third solution be to use ticket spinlocks everywhere, i.e. eliminate
the current indirection, and replace it by an indirection for just the
contention
case? As I view it, the problem for Xen aren't really the ticket locks by
themselves, but rather the extra spinning involved, which is of concern only
if a lock is contended. We're using ticket locks quite happily in our kernels,
with directed instead of global wakeup from the unlock path.
Do you have a patch to illustrate what you mean? How do you keep track
of the target vcpu for the directed wakeup? Are you using the
event-poll mechanism to block?
J
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