WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

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: "Xin, Xiaohui" <xiaohui.xin@xxxxxxxxx>
Date: Fri, 22 May 2009 13:59:42 +0800
Accept-language: en-US
Acceptlanguage: en-US
Cc: Nick Piggin <npiggin@xxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Chuck Ebbert <cebbert@xxxxxxxxxx>, Linux, List <linux-kernel@xxxxxxxxxxxxxxx>, "Li, Xin" <xin.li@xxxxxxxxx>, "Nakajima, Jun" <jun.nakajima@xxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Ingo Molnar <mingo@xxxxxxx>
Delivery-date: Thu, 21 May 2009 23:00:48 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <4A1629BA.9070309@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>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcnalaaE5TVoYk48Qv+MGvUsKaOYBwADHAwQ
Thread-topic: Performance overhead of paravirt_ops on native identified
What I mean is that if the binary of _spin_lock is like this:
(gdb) disassemble _spin_lock
Dump of assembler code for function _spin_lock:
0xffffffff80497c0f <_spin_lock+0>:      mov    1252634(%rip),%r11        # 
#0xffffffff805c9930 <test_lock_ops+16>
0xffffffff80497c16 <_spin_lock+7>:      jmpq   *%r11
End of assembler dump.
(gdb) disassemble

In this situation the binary contains a jump, the overhead is more than the 
call.

Thanks
Xiaohui

-----Original Message-----
From: Jeremy Fitzhardinge [mailto:jeremy@xxxxxxxx] 
Sent: 2009年5月22日 12:28
To: Xin, Xiaohui
Cc: Chuck Ebbert; Ingo Molnar; Li, Xin; Nakajima, Jun; H. Peter Anvin; Nick 
Piggin; Linux Kernel Mailing List; Xen-devel
Subject: Re: Performance overhead of paravirt_ops on native identified

Xin, Xiaohui wrote:
> Remember we have done one experiment with "jump", the result shows seems the 
> overhead is even more than the call.
>   

I don't think you had mentioned that. You're saying that a
call->jmp->ret is slower than call->call->ret->ret?

J
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel