From: Marc Zyngier <marc.zyngier@arm.com>
To: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Raghavendra KT <raghavendra.kt.linux@gmail.com>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"kvmarm@lists.cs.columbia.edu" <kvmarm@lists.cs.columbia.edu>,
"kvm@vger.kernel.org" <kvm@vger.kernel.org>,
Christoffer Dall <christoffer.dall@linaro.org>
Subject: Re: [PATCH 1/2] ARM: KVM: Yield CPU when vcpu executes a WFE
Date: Tue, 08 Oct 2013 16:06:59 +0100 [thread overview]
Message-ID: <52541F93.4070503@arm.com> (raw)
In-Reply-To: <52541EA3.7010403@linux.vnet.ibm.com>
On 08/10/13 16:02, Raghavendra K T wrote:
> [...]
>>>> + kvm_vcpu_on_spin(vcpu);
>>>
>>> Could you also enable CONFIG_HAVE_KVM_CPU_RELAX_INTERCEPT for arm and
>>> check if ple handler logic helps further?
>>> we would ideally get one more optimization folded into ple handler if
>>> you enable that.
>>
>> Just gave it a go, and the results are slightly (but consistently)
>> worse. Over 10 runs:
>>
>> Without RELAX_INTERCEPT: Average run 3.3623s
>> With RELAX_INTERCEPT: Average run 3.4226s
>>
>> Not massive, but still noticeable. Any clue?
>
> Is it a 4x overcommit? Probably we would have hit the code
> overhead if it were small guests.
Only 2x overcommit (dual core host, quad vcpu guests).
> RELAX_INTERCEPT is worth enabling for large guests with
> overcommits.
I'll try something more aggressive as soon as I get the time. What do
you call a large guest? So far, the hard limit on ARM is 8 vcpus.
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2013-10-08 15:07 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-10-07 15:40 [PATCH 0/2] ARM/arm64: KVM: Yield CPU when vcpu executes a WFE Marc Zyngier
2013-10-07 15:40 ` [PATCH 1/2] ARM: " Marc Zyngier
2013-10-07 16:04 ` Alexander Graf
2013-10-07 16:16 ` Marc Zyngier
2013-10-07 16:30 ` Alexander Graf
2013-10-07 16:53 ` Gleb Natapov
2013-10-09 13:09 ` Alexander Graf
2013-10-09 13:26 ` Gleb Natapov
2013-10-09 14:18 ` Marc Zyngier
2013-10-09 14:50 ` Anup Patel
2013-10-09 14:52 ` Anup Patel
2013-10-09 14:59 ` Marc Zyngier
2013-10-09 15:10 ` Anup Patel
2013-10-09 15:17 ` Marc Zyngier
2013-10-09 15:17 ` Anup Patel
2013-10-07 16:55 ` Marc Zyngier
2013-10-08 11:26 ` Raghavendra KT
2013-10-08 12:43 ` Marc Zyngier
2013-10-08 15:02 ` Raghavendra K T
2013-10-08 15:06 ` Marc Zyngier [this message]
2013-10-08 15:13 ` Raghavendra K T
2013-10-08 16:09 ` Marc Zyngier
2013-10-07 15:40 ` [PATCH 2/2] arm64: " Marc Zyngier
2013-10-07 15:52 ` Bhushan Bharat-R65777
2013-10-07 16:00 ` Marc Zyngier
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=52541F93.4070503@arm.com \
--to=marc.zyngier@arm.com \
--cc=christoffer.dall@linaro.org \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=raghavendra.kt.linux@gmail.com \
--cc=raghavendra.kt@linux.vnet.ibm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).