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Date: Tue, 11 Aug 2015 18:11:12 +0200
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From: alvise rigo <a.rigo@virtualopensystems.com>
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Subject: Re: [Qemu-devel] [RFC v4 1/9] exec.c: Add new exclusive bitmap to
	ram_list
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To: Paolo Bonzini <pbonzini@redhat.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?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>

On Tue, Aug 11, 2015 at 5:55 PM, Paolo Bonzini <pbonzini@redhat.com> wrote:
>
>
> On 11/08/2015 17:54, alvise rigo wrote:
>> This can lead to an excessive rate of flush requests, since for one
>> CPU that removes the TLB_EXCL flag, all the others that are competing
>> for the same excl address will need to flush the entire cache and
>> start all over again.
>
> Why flush the entire cache (I understand you mean TLB)?

Sorry, I meant the TLB.
If for each removal of an exclusive entry we set also the bit to 1, we
force the following LL to make a tlb_flush() on every vCPU.

alvise

>
> Paolo
>
>> If for a start we want to have a simpler implementation, I can revert
>> back to the one-bit design.