From: Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@redhat.com>
Cc: Mark Langsdorf <mark.langsdorf@amd.com>,
Joerg Roedel <joerg.roedel@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][KVM][retry 3] Add support for Pause Filtering to AMD SVM
Date: Wed, 20 May 2009 10:54:17 +0200 [thread overview]
Message-ID: <1242809657.26820.559.camel@twins> (raw)
In-Reply-To: <4A13C40B.8080608@redhat.com>
On Wed, 2009-05-20 at 11:49 +0300, Avi Kivity wrote:
> Peter Zijlstra wrote:
> >>> That said, I still thoroughly dislike this whole approach.
> >>>
> >>>
> >> Can you explain why? We have a thread that has detected that it's
> >> spinning. Keeping on spinning is a waste of cpu time. Why not let
> >> something else use the cpu?
> >>
> >
> > Because its a polling interface. I much prefer it if we were to get a
> > wakeup notification when the vcpu holding the lock releases it.
> >
>
> It's a fully virtualized guest. There's no way to get this without
> patching the guest kernel.
Yes there is.. virtualized monitor-wait stuff coupled with a
monitor-wait based spinlock implementation.
Once we go change silicon, you might as well do it right.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Avi Kivity <avi@redhat.com>
Cc: Mark Langsdorf <mark.langsdorf@amd.com>,
Joerg Roedel <joerg.roedel@amd.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][retry 3] Add support for Pause Filtering to AMD SVM
Date: Wed, 20 May 2009 10:54:17 +0200 [thread overview]
Message-ID: <1242809657.26820.559.camel@twins> (raw)
In-Reply-To: <4A13C40B.8080608@redhat.com>
On Wed, 2009-05-20 at 11:49 +0300, Avi Kivity wrote:
> Peter Zijlstra wrote:
> >>> That said, I still thoroughly dislike this whole approach.
> >>>
> >>>
> >> Can you explain why? We have a thread that has detected that it's
> >> spinning. Keeping on spinning is a waste of cpu time. Why not let
> >> something else use the cpu?
> >>
> >
> > Because its a polling interface. I much prefer it if we were to get a
> > wakeup notification when the vcpu holding the lock releases it.
> >
>
> It's a fully virtualized guest. There's no way to get this without
> patching the guest kernel.
Yes there is.. virtualized monitor-wait stuff coupled with a
monitor-wait based spinlock implementation.
Once we go change silicon, you might as well do it right.
next prev parent reply other threads:[~2009-05-20 8:54 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 ` [PATCH][KVM][retry " Avi Kivity
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 ` Peter Zijlstra [this message]
2009-05-20 8:54 ` 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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