From: Avi Kivity <avi@qumranet.com>
To: Glauber Costa <gcosta@redhat.com>
Cc: kvm-devel@lists.sourceforge.net, Marcelo Tosatti <marcelo@kvack.org>
Subject: Re: [PATCH] use slots_lock to protect writes to the wall clock
Date: Tue, 18 Mar 2008 11:52:20 +0200 [thread overview]
Message-ID: <47DF90D4.7090801@qumranet.com> (raw)
In-Reply-To: <47DF8F5B.9080606@redhat.com>
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.
> [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).
--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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next prev parent reply other threads:[~2008-03-18 9:52 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-17 20:10 [PATCH] use slots_lock to protect writes to the wall clock Glauber Costa
2008-03-18 6:42 ` Avi Kivity
2008-03-18 9:46 ` Glauber Costa
2008-03-18 9:52 ` Avi Kivity [this message]
2008-03-18 9:55 ` Glauber Costa
2008-03-18 9:58 ` Avi Kivity
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