From: Boris Ostrovsky <boris.ostrovsky@oracle.com>
To: Waiman Long <longman@redhat.com>, Juergen Gross <jgross@suse.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Cc: x86@kernel.org, xen-devel@lists.xenproject.org,
linux-kernel@vger.kernel.org,
Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: Re: [PATCH v2] xen/spinlock: Don't use pvqspinlock if only 1 vCPU
Date: Tue, 31 Jul 2018 13:05:39 -0400 [thread overview]
Message-ID: <a57a15cb-162f-6248-79c9-311756bd9560@oracle.com> (raw)
In-Reply-To: <1532036397-19449-1-git-send-email-longman@redhat.com>
On 07/19/2018 05:39 PM, Waiman Long wrote:
> On a VM with only 1 vCPU, the locking fast paths will always be
> successful. In this case, there is no need to use the the PV qspinlock
> code which has higher overhead on the unlock side than the native
> qspinlock code.
>
> The xen_pvspin veriable is also turned off in this 1 vCPU case to
> eliminate unneeded pvqspinlock initialization in xen_init_lock_cpu()
> which is run after xen_init_spinlocks().
>
> Signed-off-by: Waiman Long <longman@redhat.com>
Applied to for-linus-4.19.
-boris
prev parent reply other threads:[~2018-07-31 17:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-19 21:39 [PATCH v2] xen/spinlock: Don't use pvqspinlock if only 1 vCPU Waiman Long
2018-07-19 21:54 ` Davidlohr Bueso
2018-07-19 22:02 ` Waiman Long
2018-07-23 3:31 ` Wanpeng Li
2018-07-23 4:42 ` Davidlohr Bueso
2018-07-23 4:50 ` Davidlohr Bueso
2018-07-23 13:52 ` Waiman Long
2018-07-23 13:33 ` Waiman Long
2018-07-19 22:35 ` Boris Ostrovsky
2018-07-31 17:05 ` Boris Ostrovsky [this message]
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