From: Avi Kivity <avi@redhat.com>
To: "Langsdorf, Mark" <mark.langsdorf@amd.com>
Cc: Ingo Molnar <mingo@elte.hu>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
"Roedel, Joerg" <Joerg.Roedel@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][KVM][retry 1] Add support for Pause Filtering to AMD SVM
Date: Mon, 11 May 2009 18:40:49 +0300 [thread overview]
Message-ID: <4A084701.1090900@redhat.com> (raw)
In-Reply-To: <6453C3CB8E2B3646B0D020C1126132730362094B@sausexmb4.amd.com>
Langsdorf, Mark wrote:
>> The Linux spinlock is
>>
>> "1:\t"
>> "cmpl %0, %2\n\t"
>> "je 2f\n\t"
>> "rep ; nop\n\t"
>> "movzwl %1, %2\n\t"
>> /* don't need lfence here, because loads are in-order */
>> "jmp 1b\n"
>>
>> 5 instructions, maybe 2-3 cycles, not counting any special rep nop
>> overhead. Mark, any idea what the spin time is?
>>
>
> If I'm understanding the question right, the contested
> spin locks are being held for 5K to 10K iterations of PAUSE.
> So 10K to 30K cycles if your estimate of the spinlock
> cycle time is correct.
>
My estimate is not very reliable. Can you measure this?
btw, I'd expect you'd get much more significant improvement on Windows.
Booting 16-vcpu Windows 2008 x64 took forever on my dual core host, and
my guess is spinlock contention. Of course you'd need a working yield,
as Ingo said schedule() does very little.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2009-05-11 15:41 UTC|newest]
Thread overview: 79+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-05 14:09 [PATCH][KVM] Add support for Pause Filtering to AMD SVM Mark Langsdorf
2009-05-05 16:05 ` Bert Wesarg
2009-05-07 13:55 ` Joerg Roedel
2009-05-07 15:00 ` [PATCH][KVM][retry 1] " Mark Langsdorf
2009-05-07 15:00 ` [PATCH][retry " Mark Langsdorf
2009-05-07 15:31 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 14:15 ` Ingo Molnar
2009-05-11 14:15 ` [PATCH][retry " Ingo Molnar
2009-05-11 14:24 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 14:24 ` [PATCH][retry " Avi Kivity
2009-05-11 14:33 ` [PATCH][KVM][retry " Ingo Molnar
2009-05-11 14:33 ` [PATCH][retry " Ingo Molnar
2009-05-11 14:51 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 14:51 ` [PATCH][retry " Avi Kivity
2009-05-11 14:59 ` [PATCH][KVM][retry " Ingo Molnar
2009-05-11 14:59 ` [PATCH][retry " Ingo Molnar
2009-05-11 15:12 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 15:12 ` [PATCH][retry " Avi Kivity
2009-05-11 15:18 ` [PATCH][KVM][retry " Ingo Molnar
2009-05-11 15:18 ` [PATCH][retry " Ingo Molnar
2009-05-11 15:28 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 15:28 ` [PATCH][retry " Avi Kivity
2009-05-11 15:36 ` [PATCH][KVM][retry " Langsdorf, Mark
2009-05-11 15:36 ` [PATCH][retry " Langsdorf, Mark
2009-05-11 15:40 ` Avi Kivity [this message]
2009-05-11 15:58 ` [PATCH][KVM][retry 1] Add support for Pause Filtering to AMDSVM Langsdorf, Mark
2009-05-11 15:58 ` [PATCH][retry " Langsdorf, Mark
2009-05-11 15:01 ` [PATCH][KVM][retry 1] Add support for Pause Filtering to AMD SVM Peter Zijlstra
2009-05-11 15:01 ` [PATCH][retry " Peter Zijlstra
2009-05-11 15:06 ` [PATCH][KVM][retry " Avi Kivity
2009-05-11 15:06 ` [PATCH][retry " Avi Kivity
2009-05-11 14:42 ` [PATCH][KVM][retry " Peter Zijlstra
2009-05-11 15:05 ` Avi Kivity
2009-05-11 15:05 ` [PATCH][retry " Avi Kivity
2009-05-08 17:03 ` [PATCH][KVM][retry 2] " Mark Langsdorf
2009-05-08 17:03 ` [PATCH][retry " Mark Langsdorf
2009-05-08 18:44 ` [PATCH][KVM][retry " Avi Kivity
2009-05-08 18:44 ` [PATCH][retry " Avi Kivity
2009-05-08 18:47 ` [PATCH][KVM][retry " Langsdorf, Mark
2009-05-08 18:47 ` [PATCH][retry " Langsdorf, Mark
2009-05-19 18:56 ` [PATCH][KVM][retry 3] " Mark Langsdorf
2009-05-19 18:56 ` [PATCH][retry " Mark Langsdorf
2009-05-20 7:40 ` [PATCH][KVM][retry " Ingo Molnar
2009-05-20 7:59 ` Peter Zijlstra
2009-05-20 7:59 ` [PATCH][retry " Peter Zijlstra
2009-05-20 8:38 ` [PATCH][KVM][retry " Avi Kivity
2009-05-20 8:38 ` [PATCH][retry " Avi Kivity
2009-05-20 8:42 ` [PATCH][KVM][retry " Peter Zijlstra
2009-05-20 8:42 ` [PATCH][retry " Peter Zijlstra
2009-05-20 8:49 ` [PATCH][KVM][retry " Avi Kivity
2009-05-20 8:49 ` [PATCH][retry " Avi Kivity
2009-05-20 8:54 ` [PATCH][KVM][retry " Peter Zijlstra
2009-05-20 8:54 ` [PATCH][retry " Peter Zijlstra
2009-05-20 9:04 ` [PATCH][KVM][retry " Avi Kivity
2009-05-20 9:04 ` [PATCH][retry " Avi Kivity
2009-05-20 9:10 ` [PATCH][KVM][retry " Peter Zijlstra
2009-05-20 9:10 ` [PATCH][retry " Peter Zijlstra
2009-05-20 9:17 ` [PATCH][KVM][retry " Avi Kivity
2009-05-20 9:17 ` [PATCH][retry " Avi Kivity
2009-05-20 13:52 ` [PATCH][KVM][retry " Langsdorf, Mark
2009-05-20 13:52 ` [PATCH][retry " Langsdorf, Mark
2009-05-20 12:00 ` [PATCH][KVM][retry " Avi Kivity
2009-05-20 12:00 ` [PATCH][retry " Avi Kivity
2009-05-20 22:25 ` [PATCH][KVM][retry 4] " Mark Langsdorf
2009-05-20 22:25 ` [PATCH][retry " Mark Langsdorf
2009-05-21 8:47 ` [PATCH][KVM][retry " Avi Kivity
2009-05-21 8:47 ` [PATCH][retry " Avi Kivity
2009-07-08 5:19 ` [PATCH][KVM][retry " Sheng Yang
2009-07-08 5:19 ` [PATCH][retry " Sheng Yang
2009-07-08 14:59 ` [PATCH][KVM][retry " Langsdorf, Mark
2009-07-08 14:59 ` [PATCH][retry " Langsdorf, Mark
2009-07-09 1:50 ` [PATCH][KVM][retry " Sheng Yang
2009-07-09 1:50 ` [PATCH][retry " Sheng Yang
2009-07-22 22:40 ` [PATCH][KVM][retry " Langsdorf, Mark
2009-07-22 22:40 ` [PATCH][retry " Langsdorf, Mark
2009-08-05 9:08 ` [PATCH][KVM][retry " Zhai, Edwin
2009-08-05 9:08 ` [PATCH][retry " Zhai, Edwin
2009-05-11 14:38 ` [PATCH][KVM] " Peter Zijlstra
2009-05-11 14:51 ` Ingo Molnar
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