Re: [Qemu-devel] [RFC v2 08/11] tcg: add options for enabling MTTCG

[Sergey Fedorov]

On 12/04/16 14:59, Peter Maydell wrote:
> On 12 April 2016 at 12:48, Alex Bennée <address@hidden> wrote:
>> Sergey Fedorov <address@hidden> writes:
>>> Maybe we'd better use existing qemu accelerator framework and introduce
>>> "-machine accel=mttcg" option?
>> My worry would be breaking existing code which assumes kvm | tcg. We
>> will want to enable mttcg by default for combos that work without having
>> to tweak tooling that already uses the -machine options.
> Comments from the peanut gallery:
>  * We definitely want to just default to MTTCG where it works:
> users shouldn't have to add new command line switches to get the
> better performance etc, because in practice that won't happen
>  * Anything that adds a new command line option at all has to
> be supported practically forever, so options that are only
> useful for a transitional period are worth thinking twice about

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.

Kind regards,
Sergey