From: Waiman Long <longman@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Will Deacon <will.deacon@arm.com>, Joe Mario <jmario@redhat.com>
Subject: Re: [PATCH] x86/pvqspinlock: Use LOCK_PREFIX in __pv_queued_spin_unlock assembly code
Date: Wed, 18 Jul 2018 09:28:04 -0400 [thread overview]
Message-ID: <5d381d80-21c7-c8a7-db01-24fbbf8b1041@redhat.com> (raw)
In-Reply-To: <20180718081918.GO2494@hirez.programming.kicks-ass.net>
On 07/18/2018 04:19 AM, Peter Zijlstra wrote:
> On Tue, Jul 17, 2018 at 04:16:00PM -0400, Waiman Long wrote:
>> The LOCK_PREFIX macro should be used in the assembly
>> __raw_callee_save___pv_queued_spin_unlock code so that the lock prefix
>> can be patched out on UP systems.
> True; but does paravirt locking realy make sense on UP guests?
>
Yes, it doesn't make sense. That is why I have another kvm patch that
turns off pvqspinlock for UP guest. However, I am not that familiar with
the Xen code. So I don't have a corresponding one for Xen.
Cheers,
Longman
next prev parent reply other threads:[~2018-07-18 13:28 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-17 20:16 [PATCH] x86/pvqspinlock: Use LOCK_PREFIX in __pv_queued_spin_unlock assembly code Waiman Long
2018-07-18 8:19 ` Peter Zijlstra
2018-07-18 13:28 ` Waiman Long [this message]
2018-07-25 14:20 ` [tip:locking/urgent] locking/pvqspinlock/x86: Use LOCK_PREFIX in __pv_queued_spin_unlock() " tip-bot for Waiman Long
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