linux-kernel - Re: VM performance issue in KVM guests.

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Sat, 17 Apr 2010 22:04:38 +0300
From:	Avi Kivity <avi@...hat.com>
To:	Peter Zijlstra <peterz@...radead.org>
CC:	Srivatsa Vaddagiri <vatsa.ml@...il.com>,
	"Zhang, Xiantao" <xiantao.zhang@...el.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	Marcelo Tosatti <mtosatti@...hat.com>,
	"Yang, Xiaowei" <xiaowei.yang@...el.com>,
	"Dong, Eddie" <eddie.dong@...el.com>, "Li, Xin" <xin.li@...el.com>,
	Ingo Molnar <mingo@...e.hu>, Mike Galbraith <efault@....de>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	vatsa@...ux.vnet.ibm.com
Subject: Re: VM performance issue in KVM guests.

On 04/15/2010 04:33 PM, Peter Zijlstra wrote:
> On Thu, 2010-04-15 at 11:18 +0300, Avi Kivity wrote:
>    
>> Certainly that has even greater potential for Linux guests.  Note that
>> we spin on mutexes now, so we need to prevent preemption while the lock
>> owner is running.
>>      
> either that, or disable spinning on (para) virt kernels.

What would you do instead?

Note we can't disable spinning on Windows or pre 2.6.36 kernels.

> Para virt
> kernels could possibly extend the thing by also checking to see if the
> owner's vcpu is running.
>    

Certainly that's worth doing.

-- 
Do not meddle in the internals of kernels, for they are subtle and quick to panic.

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/