linux-kernel - Re: [PATCH v2 0/4] KVM: optimize the kvm_vcpu_on

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:   Tue, 8 Aug 2017 16:14:27 +0800
From:   "Longpeng (Mike)" <longpeng2@...wei.com>
To:     Cornelia Huck <cohuck@...hat.com>
CC:     <pbonzini@...hat.com>, <rkrcmar@...hat.com>, <agraf@...e.com>,
        <borntraeger@...ibm.com>, <christoffer.dall@...aro.org>,
        <marc.zyngier@....com>, <james.hogan@...tec.com>,
        <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <weidong.huang@...wei.com>, <arei.gonglei@...wei.com>,
        <wangxinxin.wang@...wei.com>, <longpeng.mike@...il.com>,
        <david@...hat.com>
Subject: Re: [PATCH v2 0/4] KVM: optimize the kvm_vcpu_on_spin



On 2017/8/8 15:41, Cornelia Huck wrote:

> On Tue, 8 Aug 2017 12:05:31 +0800
> "Longpeng(Mike)" <longpeng2@...wei.com> wrote:
> 
>> This is a simple optimization for kvm_vcpu_on_spin, the
>> main idea is described in patch-1's commit msg.
> 
> I think this generally looks good now.
> 
>>
>> I did some tests base on the RFC version, the result shows
>> that it can improves the performance slightly.
> 
> Did you re-run tests on this version?


Hi Cornelia,

I didn't re-run tests on V2. But the major difference between RFC and V2
is that V2 only cache result for X86 (s390/arm needn't) and V2 saves a
expensive operation ( 440-1400 cycles on my test machine ) for X86/VMX.

So I think V2's performance is at least the same as RFC or even slightly
better. :)

> 
> I would also like to see some s390 numbers; unfortunately I only have a
> z/VM environment and any performance numbers would be nearly useless
> there. Maybe somebody within IBM with a better setup can run a quick
> test?
> 
> .
> 


-- 
Regards,
Longpeng(Mike)