Re: [PATCH] use slots_lock to protect writes to the wall clock

[Glauber Costa <gcosta@redhat.com>]

Avi Kivity wrote:
> Glauber Costa wrote:
>>>
>>> This lock is fairly annoying.  What do you think about taking it in 
>>> vcpu_run unconditionally and only dropping it while in guest mode?  
>>> Most exits are mmu (or with npt, mmio) so they need to take it anyway.
>>>
>> Can't see the point. This is taken before updates to the wall clock, 
>> not system time.
> 
> I mean in general, not related to wall clock.

Oh, sorry.

>> [avi@firebolt linux-2.6 (master)]$ git grep  down_read.*slots_lock 
>> arch/x86/kvm/ | wc -l
>> 16
> 
> We take the lock for read 16 times, could be narrowed down to probably 
> once (with a drop and re-take around guest mode).

Since it will be written to so rarely, that's probably fine.



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