|
|
|
|
|
|
|
|
|
|
xen-devel
[Xen-devel] Re: Performance overhead of paravirt_ops on native identifie
To: |
Jeremy Fitzhardinge <jeremy@xxxxxxxx> |
Subject: |
[Xen-devel] Re: Performance overhead of paravirt_ops on native identified |
From: |
"H. Peter Anvin" <hpa@xxxxxxxxx> |
Date: |
Fri, 22 May 2009 15:47:05 -0700 |
Cc: |
Nick Piggin <npiggin@xxxxxxx>, "Xin, Xiaohui" <xiaohui.xin@xxxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Chuck Ebbert <cebbert@xxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, "Li, Xin" <xin.li@xxxxxxxxx>, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx> |
Delivery-date: |
Fri, 22 May 2009 15:47:55 -0700 |
Envelope-to: |
www-data@xxxxxxxxxxxxxxxxxxx |
In-reply-to: |
<4A172ADE.3010702@xxxxxxxx> |
List-help: |
<mailto:xen-devel-request@lists.xensource.com?subject=help> |
List-id: |
Xen developer discussion <xen-devel.lists.xensource.com> |
List-post: |
<mailto:xen-devel@lists.xensource.com> |
List-subscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe> |
List-unsubscribe: |
<http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe> |
References: |
<4A0B62F7.5030802@xxxxxxxx> <20090521184233.3c3e97ad@xxxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4A15DA4E.2090505@xxxxxxxx> <C85CEDA13AB1CF4D9D597824A86D2B9005760A96DA@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4A1629BA.9070309@xxxxxxxx> <C85CEDA13AB1CF4D9D597824A86D2B9005760A9940@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <4A16D3DF.5000600@xxxxxxxxx> <4A172ADE.3010702@xxxxxxxx> |
Sender: |
xen-devel-bounces@xxxxxxxxxxxxxxxxxxx |
User-agent: |
Thunderbird 2.0.0.21 (X11/20090320) |
Jeremy Fitzhardinge wrote:
>
> I did a quick experiment to see how many sites this optimisation could
> actually affect. Firstly, it does absolutely nothing with frame
> pointers enabled. Arranging for no frame pointers is quite tricky,
> since it means disabling all debugging, tracing and other things.
>
> With no frame pointers, its about 26 of 5400 indirect calls are
> immediately followed by ret (not all of those sites are pvops calls).
> With preempt disabled, this goes up to 45 sites.
>
> I haven't done any actual runtime tests, but a quick survey of the
> affected sites shows that only a couple are performance-sensitive;
> _spin_lock and _spin_lock_irq and _spin_lock_irqsave are the most obvious.
>
OK, that doesn't seem like a very productive avenue. Problem still
remains, obviously.
-hpa
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
<Prev in Thread] |
Current Thread |
[Next in Thread> |
- [Xen-devel] [tip:x86/urgent] x86: Fix performance regression caused by paravirt_ops on native kernels, (continued)
- [Xen-devel] [tip:x86/urgent] x86: Fix performance regression caused by paravirt_ops on native kernels, tip-bot for Jeremy Fitzhardinge
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, Chuck Ebbert
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, Jeremy Fitzhardinge
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, H. Peter Anvin
- [Xen-devel] RE: Performance overhead of paravirt_ops on native identified, Xin, Xiaohui
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, H. Peter Anvin
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, Jeremy Fitzhardinge
- [Xen-devel] RE: Performance overhead of paravirt_ops on native identified, Xin, Xiaohui
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, H. Peter Anvin
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified, Jeremy Fitzhardinge
- [Xen-devel] Re: Performance overhead of paravirt_ops on native identified,
H. Peter Anvin <=
|
|
|
|
|