From: Avi Kivity <avi@redhat.com>
To: Chris Wright <chrisw@redhat.com>
Cc: kvm@vger.kernel.org, qemu-devel@nongnu.org
Subject: Re: KVM call agenda for Feb 9
Date: Tue, 09 Feb 2010 08:56:20 +0200 [thread overview]
Message-ID: <4B710714.1020109@redhat.com> (raw)
In-Reply-To: <20100209012851.GJ25751@x200.localdomain>
On 02/09/2010 03:28 AM, Chris Wright wrote:
> Please send in any agenda items you are interested in covering.
>
hpet overhead on large smp guests
I measured hpet consuming about a half a core's worth of cpu on an idle
Windows 2008 R2 64-way guest. This is mostly due to futex contention,
likely from the qemu mutex.
Options:
- ignore, this is about 1% of the entire system (but overhead might
increase greatly if a workload triggers more hpet accesses)
- push hpet into kernel, with virtio-net, virtio-blk, and kernel-hpet,
there's little reason to exit into qemu
- rcuify/fine-grain qemu locks
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Chris Wright <chrisw@redhat.com>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org
Subject: [Qemu-devel] Re: KVM call agenda for Feb 9
Date: Tue, 09 Feb 2010 08:56:20 +0200 [thread overview]
Message-ID: <4B710714.1020109@redhat.com> (raw)
In-Reply-To: <20100209012851.GJ25751@x200.localdomain>
On 02/09/2010 03:28 AM, Chris Wright wrote:
> Please send in any agenda items you are interested in covering.
>
hpet overhead on large smp guests
I measured hpet consuming about a half a core's worth of cpu on an idle
Windows 2008 R2 64-way guest. This is mostly due to futex contention,
likely from the qemu mutex.
Options:
- ignore, this is about 1% of the entire system (but overhead might
increase greatly if a workload triggers more hpet accesses)
- push hpet into kernel, with virtio-net, virtio-blk, and kernel-hpet,
there's little reason to exit into qemu
- rcuify/fine-grain qemu locks
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
next prev parent reply other threads:[~2010-02-09 6:56 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-09 1:28 KVM call agenda for Feb 9 Chris Wright
2010-02-09 1:28 ` [Qemu-devel] " Chris Wright
2010-02-09 6:56 ` Avi Kivity [this message]
2010-02-09 6:56 ` [Qemu-devel] " Avi Kivity
2010-02-09 7:16 ` Alexander Graf
2010-02-09 8:52 ` Jan Kiszka
2010-02-09 8:52 ` Jan Kiszka
2010-02-09 14:18 ` Anthony Liguori
2010-02-09 14:18 ` Anthony Liguori
2010-02-09 14:38 ` Avi Kivity
2010-02-09 14:38 ` Avi Kivity
2010-02-09 15:08 ` Anthony Liguori
2010-02-09 15:08 ` Anthony Liguori
2010-02-09 15:32 ` Avi Kivity
2010-02-09 15:32 ` Avi Kivity
2010-02-09 14:15 ` Anthony Liguori
2010-02-09 14:15 ` [Qemu-devel] " Anthony Liguori
2010-02-09 14:18 ` Avi Kivity
2010-02-09 14:18 ` [Qemu-devel] " Avi Kivity
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