From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Waiman Long <waiman.long@hp.com>,
linux-arch@vger.kernel.org, Rik van Riel <riel@redhat.com>,
Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>,
Gleb Natapov <gleb@redhat.com>,
kvm@vger.kernel.org, Oleg Nesterov <oleg@redhat.com>,
Scott J Norton <scott.norton@hp.com>,
x86@kernel.org, Paolo Bonzini <paolo.bonzini@gmail.com>,
linux-kernel@vger.kernel.org,
virtualization@lists.linux-foundation.org,
Ingo Molnar <mingo@redhat.com>, Chegu Vinod <chegu_vinod@hp.com>,
David Vrabel <david.vrabel@citrix.com>,
"H. Peter Anvin" <hpa@zytor.com>,
xen-devel@lists.xenproject.org,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>
Subject: Re: [PATCH v11 14/16] pvqspinlock: Add qspinlock para-virtualization support
Date: Tue, 17 Jun 2014 16:59:15 -0400 [thread overview]
Message-ID: <20140617205915.GC29634@laptop.dumpdata.com> (raw)
In-Reply-To: <20140615131654.GJ11371@laptop.programming.kicks-ass.net>
On Sun, Jun 15, 2014 at 03:16:54PM +0200, Peter Zijlstra wrote:
> On Thu, Jun 12, 2014 at 04:48:41PM -0400, Waiman Long wrote:
> > I don't have a good understanding of the kernel alternatives mechanism.
>
> I didn't either; I do now, cost me a whole day reading up on
> alternative/paravirt code patching.
>
> See the patches I just send out; I got the 'native' case with paravirt
> enabled to be one NOP worse than the native case without paravirt -- for
> queue_spin_unlock.
>
> The lock slowpath is several nops and some pointless movs more expensive.
You could use the asm goto which would optimize the fast path to be the
'native' case. That way you wouldn't have the the nops and movs in the
path.
(And asm goto also uses the alternative_asm macros).
prev parent reply other threads:[~2014-06-17 20:59 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1401464642-33890-1-git-send-email-Waiman.Long@hp.com>
2014-05-30 15:43 ` [PATCH v11 01/16] qspinlock: A simple generic 4-byte queue spinlock Waiman Long
2014-05-30 15:43 ` [PATCH v11 02/16] qspinlock, x86: Enable x86-64 to use " Waiman Long
2014-05-30 15:43 ` [PATCH v11 03/16] qspinlock: Add pending bit Waiman Long
2014-05-30 15:43 ` [PATCH v11 04/16] qspinlock: Extract out the exchange of tail code word Waiman Long
2014-05-30 15:43 ` [PATCH v11 05/16] qspinlock: Optimize for smaller NR_CPUS Waiman Long
2014-05-30 15:43 ` [PATCH v11 06/16] qspinlock: prolong the stay in the pending bit path Waiman Long
2014-05-30 15:43 ` [PATCH v11 07/16] qspinlock: Use a simple write to grab the lock, if applicable Waiman Long
2014-05-30 15:43 ` [PATCH v11 08/16] qspinlock: Prepare for unfair lock support Waiman Long
2014-05-30 15:43 ` [PATCH v11 09/16] qspinlock, x86: Allow unfair spinlock in a virtual guest Waiman Long
2014-06-11 10:54 ` Peter Zijlstra
2014-06-11 11:38 ` Peter Zijlstra
2014-06-12 1:37 ` Long, Wai Man
2014-06-12 5:50 ` Peter Zijlstra
2014-06-12 21:08 ` Waiman Long
2014-06-15 13:14 ` Peter Zijlstra
2014-05-30 15:43 ` [PATCH v11 10/16] qspinlock: Split the MCS queuing code into a separate slowerpath Waiman Long
2014-05-30 15:43 ` [PATCH v11 11/16] pvqspinlock, x86: Rename paravirt_ticketlocks_enabled Waiman Long
2014-05-30 15:43 ` [PATCH v11 12/16] pvqspinlock, x86: Add PV data structure & methods Waiman Long
2014-05-30 15:43 ` [PATCH v11 13/16] pvqspinlock: Enable coexistence with the unfair lock Waiman Long
2014-05-30 15:44 ` [PATCH v11 14/16] pvqspinlock: Add qspinlock para-virtualization support Waiman Long
2014-05-30 15:44 ` [PATCH v11 15/16] pvqspinlock, x86: Enable PV qspinlock PV for KVM Waiman Long
2014-05-30 15:44 ` [PATCH v11 16/16] pvqspinlock, x86: Enable PV qspinlock for XEN Waiman Long
[not found] ` <1401464642-33890-7-git-send-email-Waiman.Long@hp.com>
2014-06-11 10:26 ` [PATCH v11 06/16] qspinlock: prolong the stay in the pending bit path Peter Zijlstra
2014-06-11 21:22 ` Long, Wai Man
2014-06-12 6:00 ` Peter Zijlstra
[not found] ` <20140612060032.GQ6758@twins.programming.kicks-ass.net>
2014-06-12 20:54 ` Waiman Long
2014-06-15 13:12 ` Peter Zijlstra
[not found] ` <1401464642-33890-15-git-send-email-Waiman.Long@hp.com>
2014-06-12 8:17 ` [PATCH v11 14/16] pvqspinlock: Add qspinlock para-virtualization support Peter Zijlstra
2014-06-12 20:48 ` Waiman Long
2014-06-15 13:16 ` Peter Zijlstra
2014-06-17 20:59 ` Konrad Rzeszutek Wilk [this message]
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