From: Peter Zijlstra <peterz@infradead.org>
To: Waiman Long <Waiman.Long@hp.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
Scott J Norton <scott.norton@hp.com>,
Douglas Hatch <doug.hatch@hp.com>
Subject: Re: [PATCH 2/7] locking/pvqspinlock: Allow vCPUs kick-ahead
Date: Mon, 13 Jul 2015 15:52:20 +0200 [thread overview]
Message-ID: <20150713135220.GI3644@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <1436647018-49734-3-git-send-email-Waiman.Long@hp.com>
On Sat, Jul 11, 2015 at 04:36:53PM -0400, Waiman Long wrote:
> Frequent CPU halting (vmexit) and CPU kicking (vmenter) lengthens
> critical section and block forward progress. This patch implements
> a kick-ahead mechanism where the unlocker will kick the queue head
> vCPUs as well as up to two additional vCPUs next to the queue head if
> they were halted. The kickings are done after exiting the critical
> section to improve parallelism.
>
> The amount of kick-ahead allowed depends on the number of vCPUs in
> the VM guest. This change should improve overall system performance
> in a busy overcommitted guest.
-ENONUMBERS... also highly workload sensitive, if the lock hold time is
just above our spin time you're wasting gobs of runtime.
next prev parent reply other threads:[~2015-07-13 13:52 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-11 20:36 [PATCH 0/7] locking/qspinlock: Enhance pvqspinlock & introduce queued unfair lock Waiman Long
2015-07-11 20:36 ` [PATCH 1/7] locking/pvqspinlock: Only kick CPU at unlock time Waiman Long
2015-07-13 12:02 ` Peter Zijlstra
2015-07-13 12:31 ` Peter Zijlstra
2015-07-15 1:24 ` Waiman Long
2015-07-13 13:48 ` Peter Zijlstra
2015-07-14 9:31 ` Peter Zijlstra
2015-07-15 1:31 ` Waiman Long
2015-08-03 17:00 ` [tip:locking/core] " tip-bot for Waiman Long
2015-07-11 20:36 ` [PATCH 2/7] locking/pvqspinlock: Allow vCPUs kick-ahead Waiman Long
2015-07-13 13:52 ` Peter Zijlstra [this message]
2015-07-15 1:38 ` Waiman Long
2015-07-11 20:36 ` [PATCH 3/7] locking/pvqspinlock: Implement wait-early for overcommitted guest Waiman Long
2015-07-12 8:23 ` Peter Zijlstra
2015-07-13 19:50 ` Davidlohr Bueso
2015-07-15 1:39 ` Waiman Long
2015-07-11 20:36 ` [PATCH 4/7] locking/pvqspinlock: Collect slowpath lock statistics Waiman Long
2015-07-12 8:22 ` Peter Zijlstra
2015-07-14 18:48 ` Waiman Long
2015-07-11 20:36 ` [PATCH 5/7] locking/pvqspinlock: Add pending bit support Waiman Long
2015-07-12 8:21 ` Peter Zijlstra
2015-07-14 18:47 ` Waiman Long
2015-07-11 20:36 ` [PATCH 6/7] locking/qspinlock: A fairer queued unfair lock Waiman Long
2015-07-12 8:21 ` Peter Zijlstra
2015-07-14 18:47 ` Waiman Long
2015-07-14 20:45 ` Peter Zijlstra
2015-07-11 20:36 ` [PATCH 7/7] locking/qspinlock: Collect queued unfair lock slowpath statistics Waiman Long
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