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[Qemu-devel] Re: KVM call agenda for Feb 9

From: Anthony Liguori
Subject: [Qemu-devel] Re: KVM call agenda for Feb 9
Date: Tue, 09 Feb 2010 08:15:57 -0600
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On 02/09/2010 12:56 AM, Avi Kivity wrote:
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.

- 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

Security, shamurity, let's just stick all of qemu in the kernel :-)

- rcuify/fine-grain qemu locks

Should be pretty straight forward. It would start with removing the locking within kvm*.c such that qemu_mutex isn't acquired until we dispatch I/O operations. Then we can add lockless paths for dispatch as we convert device models over.


Anthony Liguori

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