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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Thu, 10 Sep 2015 18:25:50 +0200
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Subject: Re: [Qemu-devel] [RFC v4 1/9] exec.c: Add new exclusive bitmap to
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To: alvise rigo <a.rigo@virtualopensystems.com>
Cc: mttcg@greensocs.com, Claudio Fontana <claudio.fontana@huawei.com>, QEMU Developers <qemu-devel@nongnu.org>, Jani Kokkonen <jani.kokkonen@huawei.com>, VirtualOpenSystems Technical Team <tech@virtualopensystems.com>, =?UTF-8?Q?Alex_Benn=c3=a9e?= <alex.bennee@linaro.org>



On 10/09/2015 15:04, alvise rigo wrote:
> Hi Paolo,
> 
> A brief update on this. I have a first implementation of the idea you
> proposed, though it's not working really well. The failing rate of SCs
> for some reason is very high.
> Instead of trying to fix it, I came up with this alternative design:
> we still use 8 bits per page and we group the smp_cpus in clusters of
> maximum size ceiling(smp_cpus / 8).
> Given a byte describing a certain page, its first bit will represents
> the vCPUs of index 0, 9, 17, ... and so on for the other bits.
> 
> Note that systems with eight vCPUs or less will not be affected by
> this simplified model.
> 
> Now, unless I'm missing some advantages of your proposal except the
> less aggressive memory consumption, I would go with this design.

Sounds great.

Paolo