From: Anthony Liguori <aliguori@us.ibm.com>
To: Glauber Costa <glommer@redhat.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] [PATCH] introduce on_vcpu
Date: Thu, 16 Jul 2009 16:35:11 -0500 [thread overview]
Message-ID: <4A5F9D0F.6030906@us.ibm.com> (raw)
In-Reply-To: <20090716213520.GB4019@poweredge.glommer>
Glauber Costa wrote:
> On Thu, Jul 16, 2009 at 04:25:12PM -0500, Anthony Liguori wrote:
>
>> Glauber Costa wrote:
>>
>>> Yes. Purpose of using curren_env was just to make it look more like qemu-kvm
>>> But I do understand that we'll have to change it anyway for this code to
>>> have any actual value, so I'm fine with using cpu_single_env.
>>>
>>>
>> Yeah, if qemu-kvm is introduce another global current CPUState variable,
>> then the qemu-kvm code has to change :-)
>>
>> Since qemu-kvm keeps a thread id in CPUState, it would make more sense
>> to check whether gettid() == env->thread_id, no?
>>
> disagree.
> gettid involves a syscall.
You're prematurely optimizing. a gettid syscall likely costs around
150-200 cycles.
> current_env in qemu-kvm is a TLS variable.
> probably much cheaper.
>
>
>
--
Regards,
Anthony Liguori
prev parent reply other threads:[~2009-07-16 21:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-14 16:47 [Qemu-devel] [PATCH] introduce on_vcpu Glauber Costa
2009-07-16 21:19 ` Anthony Liguori
2009-07-16 21:29 ` Glauber Costa
2009-07-16 21:25 ` Anthony Liguori
2009-07-16 21:35 ` Glauber Costa
2009-07-16 21:35 ` Anthony Liguori [this message]
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