From: Avi Kivity <avi@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
KVM <kvm@vger.kernel.org>,
linux-doc@vger.kernel.org,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Andi Kleen <andi@firstfloor.org>,
"H. Peter Anvin" <hpa@zytor.com>, Ingo Molnar <mingo@kernel.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Xen Devel <xen-devel@lists.xensource.com>, X86 <x86@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Thomas Gleixner <tglx@linutronix.de>,
Virtualization <virtualization@lists.linux-foundation.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
LKML <linux-kernel@vger.kernel.org>,
Attilio Rao <attilio.rao@citrix.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>
Subject: Re: [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks
Date: Tue, 08 May 2012 12:08:02 +0300 [thread overview]
Message-ID: <4FA8E272.5040307@redhat.com> (raw)
In-Reply-To: <4FA8579C.3000205@goop.org>
On 05/08/2012 02:15 AM, Jeremy Fitzhardinge wrote:
> On 05/07/2012 06:49 AM, Avi Kivity wrote:
> > On 05/07/2012 04:46 PM, Srivatsa Vaddagiri wrote:
> >> * Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> [2012-05-07 19:08:51]:
> >>
> >>> I 'll get hold of a PLE mc and come up with the numbers soon. but I
> >>> 'll expect the improvement around 1-3% as it was in last version.
> >> Deferring preemption (when vcpu is holding lock) may give us better than 1-3%
> >> results on PLE hardware. Something worth trying IMHO.
> > Is the improvement so low, because PLE is interfering with the patch, or
> > because PLE already does a good job?
>
> How does PLE help with ticket scheduling on unlock? I thought it would
> just help with the actual spin loops.
PLE yields to up a random vcpu, hoping it is the lock holder. This
patchset wakes up the right vcpu. For small vcpu counts the difference
is a few bad wakeups (and even a bad wakeup sometimes works, since it
can put the spinner to sleep for a bit). I expect that large vcpu
counts would show a greater difference.
--
error compiling committee.c: too many arguments to function
WARNING: multiple messages have this Message-ID (diff)
From: Avi Kivity <avi@redhat.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@suse.de>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Marcelo Tosatti <mtosatti@redhat.com>, X86 <x86@kernel.org>,
Gleb Natapov <gleb@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Attilio Rao <attilio.rao@citrix.com>,
Virtualization <virtualization@lists.linux-foundation.org>,
Xen Devel <xen-devel@lists.xensource.com>,
linux-doc@vger.kernel.org, KVM <kvm@vger.kernel.org>,
Andi Kleen <andi@firstfloor.org>,
Stefano Stabellini <stefano.stabellini@eu.citrix.com>,
Stephan Diestelhorst <stephan.diestelhorst@amd.com>,
LKML <linux-kernel@vger.kernel.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks
Date: Tue, 08 May 2012 12:08:02 +0300 [thread overview]
Message-ID: <4FA8E272.5040307@redhat.com> (raw)
In-Reply-To: <4FA8579C.3000205@goop.org>
On 05/08/2012 02:15 AM, Jeremy Fitzhardinge wrote:
> On 05/07/2012 06:49 AM, Avi Kivity wrote:
> > On 05/07/2012 04:46 PM, Srivatsa Vaddagiri wrote:
> >> * Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com> [2012-05-07 19:08:51]:
> >>
> >>> I 'll get hold of a PLE mc and come up with the numbers soon. but I
> >>> 'll expect the improvement around 1-3% as it was in last version.
> >> Deferring preemption (when vcpu is holding lock) may give us better than 1-3%
> >> results on PLE hardware. Something worth trying IMHO.
> > Is the improvement so low, because PLE is interfering with the patch, or
> > because PLE already does a good job?
>
> How does PLE help with ticket scheduling on unlock? I thought it would
> just help with the actual spin loops.
PLE yields to up a random vcpu, hoping it is the lock holder. This
patchset wakes up the right vcpu. For small vcpu counts the difference
is a few bad wakeups (and even a bad wakeup sometimes works, since it
can put the spinner to sleep for a bit). I expect that large vcpu
counts would show a greater difference.
--
error compiling committee.c: too many arguments to function
next prev parent reply other threads:[~2012-05-08 9:08 UTC|newest]
Thread overview: 139+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-02 10:06 [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks Raghavendra K T
2012-05-02 10:06 ` Raghavendra K T
2012-05-02 10:06 ` [PATCH RFC V8 1/17] x86/spinlock: Replace pv spinlocks with pv ticketlocks Raghavendra K T
2012-05-02 10:06 ` Raghavendra K T
2012-05-02 10:06 ` [PATCH RFC V8 2/17] x86/ticketlock: Don't inline _spin_unlock when using paravirt spinlocks Raghavendra K T
2012-05-02 10:06 ` Raghavendra K T
2012-05-02 10:06 ` [PATCH RFC V8 3/17] x86/ticketlock: Collapse a layer of functions Raghavendra K T
2012-05-02 10:06 ` Raghavendra K T
2012-05-02 10:07 ` [PATCH RFC V8 4/17] xen: Defer spinlock setup until boot CPU setup Raghavendra K T
2012-05-02 10:07 ` Raghavendra K T
2012-05-02 10:07 ` [PATCH RFC V8 5/17] xen/pvticketlock: Xen implementation for PV ticket locks Raghavendra K T
2012-05-02 10:07 ` Raghavendra K T
2012-05-02 10:07 ` [PATCH RFC V8 6/17] xen/pvticketlocks: Add xen_nopvspin parameter to disable xen pv ticketlocks Raghavendra K T
2012-05-02 10:07 ` Raghavendra K T
2012-05-02 10:07 ` [PATCH RFC V8 7/17] x86/pvticketlock: Use callee-save for lock_spinning Raghavendra K T
2012-05-02 10:07 ` Raghavendra K T
2012-05-02 10:07 ` [PATCH RFC V8 8/17] x86/pvticketlock: When paravirtualizing ticket locks, increment by 2 Raghavendra K T
2012-05-02 10:07 ` Raghavendra K T
2012-05-02 10:08 ` [PATCH RFC V8 9/17] Split out rate limiting from jump_label.h Raghavendra K T
2012-05-02 10:08 ` Raghavendra K T
2012-05-02 10:08 ` [PATCH RFC V8 10/17] x86/ticketlock: Add slowpath logic Raghavendra K T
2012-05-02 10:08 ` Raghavendra K T
2012-05-02 10:08 ` [PATCH RFC V8 11/17] xen/pvticketlock: Allow interrupts to be enabled while blocking Raghavendra K T
2012-05-02 10:08 ` Raghavendra K T
2012-05-02 10:08 ` [PATCH RFC V8 12/17] xen: Enable PV ticketlocks on HVM Xen Raghavendra K T
2012-05-02 10:08 ` Raghavendra K T
2012-05-02 10:08 ` [PATCH RFC V8 13/17] kvm hypervisor : Add a hypercall to KVM hypervisor to support pv-ticketlocks Raghavendra K T
2012-05-02 10:08 ` Raghavendra K T
2012-05-02 10:09 ` [PATCH RFC V8 14/17] kvm : Fold pv_unhalt flag into GET_MP_STATE ioctl to aid migration Raghavendra K T
2012-05-02 10:09 ` Raghavendra K T
2012-05-02 10:09 ` [PATCH RFC V8 15/17] kvm guest : Add configuration support to enable debug information for KVM Guests Raghavendra K T
2012-05-02 10:09 ` Raghavendra K T
2012-05-02 10:09 ` [PATCH RFC V8 16/17] kvm : Paravirtual ticketlocks support for linux guests running on KVM hypervisor Raghavendra K T
2012-05-02 10:09 ` Raghavendra K T
2012-05-02 10:09 ` [PATCH RFC V8 17/17] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock Raghavendra K T
2012-05-02 10:09 ` Raghavendra K T
2012-05-30 11:54 ` Jan Kiszka
2012-05-30 13:44 ` Raghavendra K T
2012-05-30 13:44 ` Raghavendra K T
2012-05-30 11:54 ` Jan Kiszka
2012-05-07 8:29 ` [PATCH RFC V8 0/17] Paravirtualized ticket spinlocks Ingo Molnar
2012-05-07 8:29 ` Ingo Molnar
2012-05-07 8:32 ` Avi Kivity
2012-05-07 8:32 ` Avi Kivity
2012-05-07 10:58 ` Raghavendra K T
2012-05-07 10:58 ` Raghavendra K T
2012-05-07 12:06 ` Avi Kivity
2012-05-07 12:06 ` Avi Kivity
2012-05-07 13:20 ` Raghavendra K T
2012-05-07 13:20 ` Raghavendra K T
2012-05-07 13:20 ` Raghavendra K T
2012-05-07 13:20 ` Raghavendra K T
2012-05-07 13:22 ` Avi Kivity
2012-05-07 13:22 ` Avi Kivity
2012-05-07 13:38 ` Raghavendra K T
2012-05-07 13:38 ` Raghavendra K T
2012-05-07 13:38 ` Raghavendra K T
2012-05-07 13:46 ` Srivatsa Vaddagiri
2012-05-07 13:46 ` Srivatsa Vaddagiri
2012-05-07 13:46 ` Srivatsa Vaddagiri
2012-05-07 13:49 ` Avi Kivity
2012-05-07 13:49 ` Avi Kivity
2012-05-07 13:53 ` Raghavendra K T
2012-05-07 13:53 ` Raghavendra K T
2012-05-07 13:53 ` Raghavendra K T
2012-05-07 13:53 ` Raghavendra K T
2012-05-07 13:58 ` Avi Kivity
2012-05-07 13:58 ` Avi Kivity
2012-05-07 14:47 ` Raghavendra K T
2012-05-07 14:47 ` Raghavendra K T
2012-05-07 14:52 ` Avi Kivity
2012-05-07 14:52 ` Avi Kivity
2012-05-07 14:54 ` Avi Kivity
2012-05-07 14:54 ` Avi Kivity
2012-05-07 17:25 ` Ingo Molnar
2012-05-07 17:25 ` Ingo Molnar
2012-05-07 17:25 ` Ingo Molnar
2012-05-07 17:25 ` Ingo Molnar
2012-05-07 20:42 ` Thomas Gleixner
2012-05-07 20:42 ` Thomas Gleixner
2012-05-07 20:42 ` Thomas Gleixner
2012-05-08 6:46 ` Nikunj A Dadhania
2012-05-08 6:46 ` Nikunj A Dadhania
2012-05-08 6:46 ` Nikunj A Dadhania
2012-05-08 6:46 ` Nikunj A Dadhania
2012-05-07 20:42 ` Thomas Gleixner
2012-05-15 11:26 ` [Xen-devel] " Jan Beulich
2012-05-15 11:26 ` Jan Beulich
2012-05-15 11:26 ` Jan Beulich
2012-05-08 5:25 ` Raghavendra K T
2012-05-08 5:25 ` Raghavendra K T
2012-05-08 5:25 ` Raghavendra K T
2012-05-08 5:25 ` Raghavendra K T
2012-05-13 18:45 ` Raghavendra K T
2012-05-13 18:45 ` Raghavendra K T
2012-05-13 18:45 ` Raghavendra K T
2012-05-14 4:57 ` Nikunj A Dadhania
2012-05-14 4:57 ` Nikunj A Dadhania
2012-05-14 4:57 ` Nikunj A Dadhania
2012-05-14 4:57 ` Nikunj A Dadhania
2012-05-14 9:01 ` Raghavendra K T
2012-05-14 9:01 ` Raghavendra K T
2012-05-14 9:01 ` Raghavendra K T
2012-05-14 9:01 ` Raghavendra K T
2012-05-14 7:38 ` Jeremy Fitzhardinge
2012-05-14 7:38 ` Jeremy Fitzhardinge
2012-05-14 8:11 ` Raghavendra K T
2012-05-14 8:11 ` Raghavendra K T
2012-05-16 3:19 ` Raghavendra K T
2012-05-16 3:19 ` Raghavendra K T
2012-05-16 3:19 ` Raghavendra K T
2012-05-30 11:26 ` Raghavendra K T
2012-05-30 11:26 ` Raghavendra K T
2012-05-30 11:26 ` Raghavendra K T
2012-05-30 11:26 ` Raghavendra K T
2012-06-14 12:21 ` Raghavendra K T
2012-06-14 12:21 ` Raghavendra K T
2012-06-14 12:21 ` Raghavendra K T
2012-06-14 12:21 ` Raghavendra K T
2012-05-07 13:55 ` Srivatsa Vaddagiri
2012-05-07 13:55 ` Srivatsa Vaddagiri
2012-05-07 13:55 ` Srivatsa Vaddagiri
2012-05-07 23:15 ` Jeremy Fitzhardinge
2012-05-07 23:15 ` Jeremy Fitzhardinge
2012-05-08 1:13 ` Raghavendra K T
2012-05-08 1:13 ` Raghavendra K T
2012-05-08 9:08 ` Avi Kivity [this message]
2012-05-08 9:08 ` Avi Kivity
2012-05-07 13:56 ` Raghavendra K T
2012-05-07 13:56 ` Raghavendra K T
2012-05-07 13:56 ` Raghavendra K T
2012-05-07 13:56 ` Raghavendra K T
2012-05-07 13:46 ` Srivatsa Vaddagiri
2012-05-07 13:38 ` Raghavendra K T
2012-05-13 17:59 ` Raghavendra K T
2012-05-13 17:59 ` Raghavendra K T
2012-05-13 17:59 ` Raghavendra K T
2012-05-13 17:59 ` Raghavendra K T
2012-05-07 8:29 ` Ingo Molnar
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