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/
Home Products Support Community News


[Xen-devel] Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support p

To: vatsa@xxxxxxxxxxxxxxxxxx
Subject: [Xen-devel] Re: [PATCH 2/3] kvm hypervisor : Add hypercalls to support pv-ticketlock
From: Rik van Riel <riel@xxxxxxxxxx>
Date: Sat, 22 Jan 2011 09:53:46 -0500
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Américo , Nick Piggin <npiggin@xxxxxxxxx>, kvm@xxxxxxxxxxxxxxx, Peter Zijlstra <peterz@xxxxxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Jan Beulich <JBeulich@xxxxxxxxxx>, Eric Dumazet <dada1@xxxxxxxxxxxxx>, Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>, suzuki@xxxxxxxxxx, Avi Kivity <avi@xxxxxxxxxx>, Wang <xiyou.wangcong@xxxxxxxxx>, Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxx>, Linux Virtualization <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>
Delivery-date: Sat, 22 Jan 2011 06:55:23 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <20110122061417.GA7258@xxxxxxxxxxxxxxxxxx>
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: <cover.1289940821.git.jeremy.fitzhardinge@xxxxxxxxxx> <20110119164432.GA30669@xxxxxxxxxxxxxxxxxx> <20110119171239.GB726@xxxxxxxxxxxxxxxxxx> <1295457672.28776.144.camel@laptop> <4D373340.60608@xxxxxxxx> <20110120115958.GB11177@xxxxxxxxxxxxxxxxxx> <4D38774B.6070704@xxxxxxxx> <20110121140208.GA13609@xxxxxxxxxxxxxxxxxx> <4D399CBD.10506@xxxxxxxxxx> <20110122061417.GA7258@xxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv: Gecko/20101209 Fedora/3.1.7-0.35.b3pre.fc13 Lightning/1.0b3pre Thunderbird/3.1.7
On 01/22/2011 01:14 AM, Srivatsa Vaddagiri wrote:

Also it may be possible for the pv-ticketlocks to track owning vcpu and make use
of a yield-to interface as further optimization to avoid the
"others-get-more-time" problem, but Peterz rightly pointed that PI would be a
better solution there than yield-to. So overall IMO kvm_vcpu_on_spin+yield_to
could be the best solution for unmodified guests, while paravirtualized
ticketlocks + some sort of PI would be a better solution where we have the
luxury of modifying guest sources!

Agreed, for unmodified guests (which is what people will mostly be
running for the next couple of years), we have little choice but
to use PLE + kvm_vcpu_on_spin + yield_to.

The main question that remains is whether the PV ticketlocks are
a large enough improvement to also merge those.  I expect they
will be, and we'll see so in the benchmark numbers.

All rights reversed

Xen-devel mailing list

<Prev in Thread] Current Thread [Next in Thread>