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From: Sergey Fedorov <serge.fdrv@gmail.com>
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Date: Tue, 12 Apr 2016 16:19:42 +0300
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Subject: Re: [Qemu-devel] [RFC v2 08/11] tcg: add options for enabling MTTCG
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To: Pavel Dovgalyuk <dovgaluk@ispras.ru>, 'KONRAD Frederic' <fred.konrad@greensocs.com>, 'Peter Maydell' <peter.maydell@linaro.org>, =?UTF-8?Q?'Alex_Benn=c3=a9e'?= <alex.bennee@linaro.org>
Cc: 'MTTCG Devel' <mttcg@listserver.greensocs.com>, 'Alvise Rigo' <a.rigo@virtualopensystems.com>, "'Emilio G. Cota'" <cota@braap.org>, 'QEMU Developers' <qemu-devel@nongnu.org>, 'Mark Burton' <mark.burton@greensocs.com>, 'Paolo Bonzini' <pbonzini@redhat.com>, "'J. Kiszka'" <jan.kiszka@siemens.com>, 'Richard Henderson' <rth@twiddle.net>, 'Claudio Fontana' <claudio.fontana@huawei.com>, 'Peter Crosthwaite' <crosthwaite.peter@gmail.com>, =?UTF-8?Q?'Andreas_F=c3=a4rber'?= <afaerber@suse.de>

On 12/04/16 16:03, Pavel Dovgalyuk wrote:
>> From: mttcg-request@listserver.greensocs.com [mailto:mttcg-request@listserver.greensocs.com]
>> On 12/04/16 15:50, KONRAD Frederic wrote:
>>>> Yes, but users may like to have an option to disable MTTCG for some
>>>> reason. I'm also concerned about icount mode: not sure how to account
>>>> virtual time when all vCPUs run in parallel.
>>> I'm thinking the same, we don't have a solution for icount yet.
>>> The reverse execution support is probably badly broken as well.
>> Reverse execution doesn't even seem to support more than a single core.
>> As of icount, it looks like to be incompatible with MTTCG.
> It doesn't, because there is no multicore support for tcg yet.
> I think, that we have to find some solution for icount (even if it will be slow).

Synchronize all vCPUs against their instruction counters? I wonder would
it be of much use in MTTCG mode if it turns out to be quite slow?
Anyhow, valid point, we should think about it.

Kind regards,
Sergey