From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>, Waiman Long <waiman.long@hp.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Gleb Natapov <gleb@redhat.com>,
virtualization@lists.linux-foundation.org,
Andi Kleen <andi@firstfloor.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Michel Lespinasse <walken@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org, kvm@vger.kernel.org, x86@kernel.org,
Alok Kataria <akataria@vmware.com>,
Ingo Molnar <mingo@redhat.com>,
xen-devel@lists.xenproject.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Scott J Norton <scott.norton@hp.com>,
Steven Rostedt <rostedt@goodmis.org>,
Chris Wright <chrisw@sous-sol.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Aswin Chandramouleeswaran <aswin@hp.com>,
Oleg Nesterov <oleg@redhat.com>
Subject: Re: [PATCH v6 05/11] pvqspinlock, x86: Allow unfair spinlock in a PV guest
Date: Fri, 14 Mar 2014 09:48:09 +0100 [thread overview]
Message-ID: <5322C249.6060502@redhat.com> (raw)
In-Reply-To: <20140314083001.GN27965@twins.programming.kicks-ass.net>
Il 14/03/2014 09:30, Peter Zijlstra ha scritto:
> Take the situation of 3 (v)CPUs where cpu0 holds the lock but is
> preempted. cpu1 queues, cpu2 queues. Then cpu1 gets preempted, after
> which cpu0 gets back online.
>
> The simple test-and-set lock will now let cpu2 acquire. Your queue
> however will just sit there spinning, waiting for cpu1 to come back from
> holiday.
>
> I think you're way over engineering this. Just do the simple
> test-and-set lock for virt && !paravirt (as I think Paolo Bonzini
> suggested RHEL6 already does).
Exactly.
Paolo
WARNING: multiple messages have this Message-ID (diff)
From: Paolo Bonzini <pbonzini@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>, Waiman Long <waiman.long@hp.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
kvm@vger.kernel.org, Boris Ostrovsky <boris.ostrovsky@oracle.com>,
virtualization@lists.linux-foundation.org,
Andi Kleen <andi@firstfloor.org>,
"H. Peter Anvin" <hpa@zytor.com>,
Michel Lespinasse <walken@google.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arch@vger.kernel.org, Gleb Natapov <gleb@redhat.com>,
x86@kernel.org, Ingo Molnar <mingo@redhat.com>,
xen-devel@lists.xenproject.org,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Rik van Riel <riel@redhat.com>, Arnd Bergmann <arnd@arndb.de>,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
Scott J Norton <scott.norton@hp.com>,
Steven Rostedt <rostedt@goodmis.org>,
Chris Wright <chrisw@sous-sol.org>,
Oleg Nesterov <oleg@redhat.com>,
Alok Kataria <akataria@vmware.com>,
Aswin Chandramouleeswaran <aswin@hp.com>
Subject: Re: [PATCH v6 05/11] pvqspinlock, x86: Allow unfair spinlock in a PV guest
Date: Fri, 14 Mar 2014 09:48:09 +0100 [thread overview]
Message-ID: <5322C249.6060502@redhat.com> (raw)
Message-ID: <20140314084809.bE1y5DCMukHbLNc_n_zm0zKzSL7ZurUYR_b67WUbOfs@z> (raw)
In-Reply-To: <20140314083001.GN27965@twins.programming.kicks-ass.net>
Il 14/03/2014 09:30, Peter Zijlstra ha scritto:
> Take the situation of 3 (v)CPUs where cpu0 holds the lock but is
> preempted. cpu1 queues, cpu2 queues. Then cpu1 gets preempted, after
> which cpu0 gets back online.
>
> The simple test-and-set lock will now let cpu2 acquire. Your queue
> however will just sit there spinning, waiting for cpu1 to come back from
> holiday.
>
> I think you're way over engineering this. Just do the simple
> test-and-set lock for virt && !paravirt (as I think Paolo Bonzini
> suggested RHEL6 already does).
Exactly.
Paolo
next prev parent reply other threads:[~2014-03-14 8:48 UTC|newest]
Thread overview: 135+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-12 18:54 [PATCH v6 00/11] qspinlock: a 4-byte queue spinlock with PV support Waiman Long
2014-03-12 18:54 ` [PATCH v6 01/11] qspinlock: A generic 4-byte queue spinlock implementation Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 02/11] qspinlock, x86: Enable x86-64 to use queue spinlock Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 03/11] qspinlock: More optimized code for smaller NR_CPUS Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 04/11] qspinlock: Optimized code path for 2 contending tasks Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 19:08 ` Waiman Long
2014-03-12 19:08 ` Waiman Long
2014-03-12 19:08 ` Waiman Long
2014-03-13 13:57 ` Peter Zijlstra
2014-03-13 13:57 ` Peter Zijlstra
2014-03-13 13:57 ` Peter Zijlstra
2014-03-17 17:23 ` Waiman Long
2014-03-17 17:23 ` Waiman Long
2014-03-17 17:23 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 05/11] pvqspinlock, x86: Allow unfair spinlock in a PV guest Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-13 10:54 ` David Vrabel
2014-03-13 10:54 ` David Vrabel
2014-03-13 10:54 ` David Vrabel
2014-03-13 13:16 ` Paolo Bonzini
2014-03-13 13:16 ` Paolo Bonzini
2014-03-13 13:16 ` Paolo Bonzini
2014-03-13 13:16 ` Paolo Bonzini
2014-03-17 19:05 ` Konrad Rzeszutek Wilk
2014-03-17 19:05 ` Konrad Rzeszutek Wilk
2014-03-17 19:05 ` Konrad Rzeszutek Wilk
2014-03-18 8:14 ` Paolo Bonzini
2014-03-18 8:14 ` Paolo Bonzini
2014-03-19 3:15 ` Waiman Long
2014-03-19 3:15 ` Waiman Long
2014-03-19 3:15 ` Waiman Long
2014-03-19 3:15 ` Waiman Long
2014-03-19 10:07 ` Paolo Bonzini
2014-03-19 16:58 ` Waiman Long
2014-03-19 16:58 ` Waiman Long
2014-03-19 17:08 ` Paolo Bonzini
2014-03-19 17:08 ` Paolo Bonzini
2014-03-19 17:08 ` Paolo Bonzini
2014-03-19 16:58 ` Waiman Long
2014-03-19 10:07 ` Paolo Bonzini
2014-03-19 10:07 ` Paolo Bonzini
2014-03-19 3:15 ` Waiman Long
2014-03-18 8:14 ` Paolo Bonzini
2014-03-17 19:05 ` Konrad Rzeszutek Wilk
2014-03-13 19:03 ` Waiman Long
2014-03-13 19:03 ` Waiman Long
2014-03-13 19:03 ` Waiman Long
2014-03-13 15:15 ` Peter Zijlstra
2014-03-13 15:15 ` Peter Zijlstra
2014-03-13 20:05 ` Waiman Long
2014-03-13 20:05 ` Waiman Long
2014-03-13 20:05 ` Waiman Long
2014-03-14 8:30 ` Peter Zijlstra
2014-03-14 8:30 ` Peter Zijlstra
2014-03-14 8:30 ` Peter Zijlstra
2014-03-14 8:48 ` Paolo Bonzini [this message]
2014-03-14 8:48 ` Paolo Bonzini
2014-03-14 8:48 ` Paolo Bonzini
2014-03-17 17:44 ` Waiman Long
2014-03-17 17:44 ` Waiman Long
2014-03-17 17:44 ` Waiman Long
2014-03-17 18:54 ` Peter Zijlstra
2014-03-17 18:54 ` Peter Zijlstra
2014-03-18 8:16 ` Paolo Bonzini
2014-03-18 8:16 ` Paolo Bonzini
2014-03-18 8:16 ` Paolo Bonzini
2014-03-19 3:08 ` Waiman Long
2014-03-19 3:08 ` Waiman Long
2014-03-19 3:08 ` Waiman Long
2014-03-17 18:54 ` Peter Zijlstra
2014-03-17 19:10 ` Konrad Rzeszutek Wilk
2014-03-17 19:10 ` Konrad Rzeszutek Wilk
2014-03-19 3:11 ` Waiman Long
2014-03-19 3:11 ` Waiman Long
2014-03-19 15:25 ` Konrad Rzeszutek Wilk
2014-03-19 15:25 ` Konrad Rzeszutek Wilk
2014-03-19 15:25 ` Konrad Rzeszutek Wilk
2014-03-19 3:11 ` Waiman Long
2014-03-17 19:10 ` Konrad Rzeszutek Wilk
2014-03-13 15:15 ` Peter Zijlstra
2014-03-12 18:54 ` [PATCH v6 06/11] pvqspinlock, x86: Allow unfair queue spinlock in a KVM guest Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 07/11] pvqspinlock, x86: Allow unfair queue spinlock in a XEN guest Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH v6 08/11] pvqspinlock, x86: Rename paravirt_ticketlocks_enabled Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH RFC v6 09/11] pvqspinlock, x86: Add qspinlock para-virtualization support Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-13 11:21 ` David Vrabel
2014-03-13 11:21 ` David Vrabel
2014-03-13 11:21 ` David Vrabel
2014-03-13 13:57 ` Paolo Bonzini
2014-03-13 13:57 ` Paolo Bonzini
2014-03-13 13:57 ` Paolo Bonzini
2014-03-13 13:57 ` Paolo Bonzini
2014-03-13 19:49 ` Waiman Long
2014-03-13 19:49 ` Waiman Long
2014-03-13 19:49 ` Waiman Long
2014-03-14 9:44 ` Paolo Bonzini
2014-03-14 9:44 ` Paolo Bonzini
2014-03-14 9:44 ` Paolo Bonzini
2014-03-13 19:49 ` Waiman Long
2014-03-13 19:49 ` Waiman Long
2014-03-13 13:57 ` Paolo Bonzini
2014-03-13 19:05 ` Waiman Long
2014-03-13 19:05 ` Waiman Long
2014-03-13 19:05 ` Waiman Long
2014-03-12 18:54 ` [PATCH RFC v6 10/11] pvqspinlock, x86: Enable qspinlock PV support for KVM Waiman Long
2014-03-13 13:59 ` Paolo Bonzini
2014-03-13 13:59 ` Paolo Bonzini
2014-03-13 19:13 ` Waiman Long
2014-03-13 19:13 ` Waiman Long
2014-03-14 8:42 ` Paolo Bonzini
2014-03-14 8:42 ` Paolo Bonzini
2014-03-17 17:47 ` Waiman Long
2014-03-17 17:47 ` Waiman Long
2014-03-17 17:47 ` Waiman Long
2014-03-18 8:18 ` Paolo Bonzini
2014-03-18 8:18 ` Paolo Bonzini
2014-03-18 8:18 ` Paolo Bonzini
2014-03-14 8:42 ` Paolo Bonzini
2014-03-13 13:59 ` Paolo Bonzini
2014-03-13 15:25 ` Peter Zijlstra
2014-03-13 15:25 ` Peter Zijlstra
2014-03-13 15:25 ` Peter Zijlstra
2014-03-13 20:09 ` Waiman Long
2014-03-13 20:09 ` Waiman Long
2014-03-13 20:09 ` Waiman Long
2014-03-12 18:54 ` Waiman Long
2014-03-12 18:54 ` [PATCH RFC v6 11/11] pvqspinlock, x86: Enable qspinlock PV support for XEN Waiman Long
2014-03-12 18:54 ` Waiman Long
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