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xen-devel
Re: [Xen-devel] Performance overhead of paravirt_ops on nativeidentifie
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To: |
"Jeremy Fitzhardinge" <jeremy@xxxxxxxx> |
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Subject: |
Re: [Xen-devel] Performance overhead of paravirt_ops on nativeidentified |
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From: |
"Jan Beulich" <JBeulich@xxxxxxxxxx> |
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Date: |
Fri, 15 May 2009 09:10:20 +0100 |
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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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Fri, 15 May 2009 01:11:16 -0700 |
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>>> Jeremy Fitzhardinge <jeremy@xxxxxxxx> 14.05.09 19:45 >>>
>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?
A patch for the pv-ops kernel would require some time. What I can give you
right away - just for reference - are the sources we currently use in our
kernel:
attached.
Jan
spinlock.h
Description: Binary data
spinlock.c
Description: Binary data
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