From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH 02/11] Add "handle page fault" PV helper.
Date: Sun, 8 Nov 2009 13:51:35 +0100 [thread overview]
Message-ID: <20091108125135.GA13099@elte.hu> (raw)
In-Reply-To: <4AF6BCE5.3030701@redhat.com>
* Avi Kivity <avi@redhat.com> wrote:
> On 11/08/2009 01:36 PM, Ingo Molnar wrote:
> >>Three existing callbacks are: kmemcheck, mmiotrace, notifier. Two
> >>of them kmemcheck, mmiotrace are enabled only for debugging, should
> >>not be performance concern. And notifier call sites (two of them)
> >>are deliberately, as explained by comment, not at the function entry,
> >>so can't be unified with others. (And kmemcheck also has two different
> >>call site BTW)
> >
> > We want mmiotrace to be generic distro capable so the overhead when
> > the hook is not used is of concern.
>
> Maybe we should generalize paravirt-ops patching in case if (x) f() is
> deemed too expensive.
Yes, that's a nice idea. We have quite a number of 'conditional
callbacks' in various critical paths that could be made lighter via such
a technique.
It would also free new callbacks from the 'it increases overhead even if
unused' criticism and made it easier to add them.
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@elte.hu>
To: Avi Kivity <avi@redhat.com>
Cc: Gleb Natapov <gleb@redhat.com>,
kvm@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Fr??d??ric Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH 02/11] Add "handle page fault" PV helper.
Date: Sun, 8 Nov 2009 13:51:35 +0100 [thread overview]
Message-ID: <20091108125135.GA13099@elte.hu> (raw)
In-Reply-To: <4AF6BCE5.3030701@redhat.com>
* Avi Kivity <avi@redhat.com> wrote:
> On 11/08/2009 01:36 PM, Ingo Molnar wrote:
> >>Three existing callbacks are: kmemcheck, mmiotrace, notifier. Two
> >>of them kmemcheck, mmiotrace are enabled only for debugging, should
> >>not be performance concern. And notifier call sites (two of them)
> >>are deliberately, as explained by comment, not at the function entry,
> >>so can't be unified with others. (And kmemcheck also has two different
> >>call site BTW)
> >
> > We want mmiotrace to be generic distro capable so the overhead when
> > the hook is not used is of concern.
>
> Maybe we should generalize paravirt-ops patching in case if (x) f() is
> deemed too expensive.
Yes, that's a nice idea. We have quite a number of 'conditional
callbacks' in various critical paths that could be made lighter via such
a technique.
It would also free new callbacks from the 'it increases overhead even if
unused' criticism and made it easier to add them.
Ingo
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next prev parent reply other threads:[~2009-11-08 12:52 UTC|newest]
Thread overview: 112+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-11-01 11:56 [PATCH 00/11] KVM: Add asynchronous page fault for PV guest Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-01 11:56 ` [PATCH 01/11] Add shared memory hypercall to PV Linux guest Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 4:27 ` Rik van Riel
2009-11-02 4:27 ` Rik van Riel
2009-11-02 7:07 ` Gleb Natapov
2009-11-02 7:07 ` Gleb Natapov
2009-11-02 12:18 ` Avi Kivity
2009-11-02 12:18 ` Avi Kivity
2009-11-02 16:18 ` Gleb Natapov
2009-11-02 16:18 ` Gleb Natapov
2009-11-03 5:15 ` Avi Kivity
2009-11-03 5:15 ` Avi Kivity
2009-11-03 7:16 ` Gleb Natapov
2009-11-03 7:16 ` Gleb Natapov
2009-11-03 7:40 ` Avi Kivity
2009-11-03 7:40 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 02/11] Add "handle page fault" PV helper Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 9:22 ` Ingo Molnar
2009-11-02 9:22 ` Ingo Molnar
2009-11-02 16:04 ` Gleb Natapov
2009-11-02 16:04 ` Gleb Natapov
2009-11-02 16:12 ` Ingo Molnar
2009-11-02 16:12 ` Ingo Molnar
2009-11-02 16:22 ` Gleb Natapov
2009-11-02 16:22 ` Gleb Natapov
2009-11-02 16:29 ` Ingo Molnar
2009-11-02 16:29 ` Ingo Molnar
2009-11-02 16:31 ` Gleb Natapov
2009-11-02 16:31 ` Gleb Natapov
2009-11-02 17:42 ` Gleb Natapov
2009-11-02 17:42 ` Gleb Natapov
2009-11-08 11:36 ` Ingo Molnar
2009-11-08 11:36 ` Ingo Molnar
2009-11-08 12:43 ` Avi Kivity
2009-11-08 12:43 ` Avi Kivity
2009-11-08 12:51 ` Ingo Molnar [this message]
2009-11-08 12:51 ` Ingo Molnar
2009-11-08 13:01 ` Avi Kivity
2009-11-08 13:01 ` Avi Kivity
2009-11-08 13:05 ` Ingo Molnar
2009-11-08 13:05 ` Ingo Molnar
2009-11-08 13:08 ` Avi Kivity
2009-11-08 13:08 ` Avi Kivity
2009-11-08 16:44 ` H. Peter Anvin
2009-11-08 16:44 ` H. Peter Anvin
2009-11-08 16:47 ` Ingo Molnar
2009-11-08 16:47 ` Ingo Molnar
2009-11-02 19:03 ` Rik van Riel
2009-11-02 19:03 ` Rik van Riel
2009-11-02 19:33 ` Avi Kivity
2009-11-02 19:33 ` Avi Kivity
2009-11-02 23:35 ` Rik van Riel
2009-11-02 23:35 ` Rik van Riel
2009-11-03 4:57 ` Avi Kivity
2009-11-03 4:57 ` Avi Kivity
2009-11-03 4:57 ` Avi Kivity
2009-11-05 6:44 ` Tian, Kevin
2009-11-05 6:44 ` Tian, Kevin
2009-11-05 8:22 ` Avi Kivity
2009-11-05 8:22 ` Avi Kivity
2009-11-05 8:22 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 03/11] Handle asynchronous page fault in a PV guest Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 12:38 ` Avi Kivity
2009-11-02 12:38 ` Avi Kivity
2009-11-02 15:54 ` Gleb Natapov
2009-11-02 15:54 ` Gleb Natapov
2009-11-03 14:14 ` Marcelo Tosatti
2009-11-03 14:14 ` Marcelo Tosatti
2009-11-03 14:25 ` Gleb Natapov
2009-11-03 14:25 ` Gleb Natapov
2009-11-03 14:32 ` Marcelo Tosatti
2009-11-03 14:32 ` Marcelo Tosatti
2009-11-03 14:38 ` Avi Kivity
2009-11-03 14:38 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 04/11] Export __get_user_pages_fast Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 9:23 ` Ingo Molnar
2009-11-02 9:23 ` Ingo Molnar
2009-11-01 11:56 ` [PATCH 05/11] Add get_user_pages() variant that fails if major fault is required Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 19:05 ` Rik van Riel
2009-11-02 19:05 ` Rik van Riel
2009-11-01 11:56 ` [PATCH 06/11] Inject asynchronous page fault into a guest if page is swapped out Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 12:56 ` Avi Kivity
2009-11-02 12:56 ` Avi Kivity
2009-11-02 15:41 ` Gleb Natapov
2009-11-02 15:41 ` Gleb Natapov
2009-11-01 11:56 ` [PATCH 07/11] Retry fault before vmentry Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 13:03 ` Avi Kivity
2009-11-02 13:03 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 08/11] Add "wait for page" hypercall Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 13:05 ` Avi Kivity
2009-11-02 13:05 ` Avi Kivity
2009-11-02 15:13 ` Gleb Natapov
2009-11-02 15:13 ` Gleb Natapov
2009-11-02 15:19 ` Avi Kivity
2009-11-02 15:19 ` Avi Kivity
2009-11-01 11:56 ` [PATCH 09/11] Maintain preemptability count even for !CONFIG_PREEMPT kernels Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-02 9:24 ` Ingo Molnar
2009-11-02 9:24 ` Ingo Molnar
2009-11-01 11:56 ` [PATCH 10/11] Handle async PF in non preemptable context Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
2009-11-01 11:56 ` [PATCH 11/11] Send async PF when guest is not in userspace too Gleb Natapov
2009-11-01 11:56 ` Gleb Natapov
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