From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Nick Piggin <npiggin@suse.de>, Jan Beulich <JBeulich@novell.com>,
Avi Kivity <avi@redhat.com>,
Xen-devel <xen-devel@lists.xensource.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH 00/20] x86: ticket lock rewrite and paravirtualization
Date: Fri, 12 Nov 2010 14:12:35 -0800 [thread overview]
Message-ID: <4CDDBBD3.5050903@zytor.com> (raw)
In-Reply-To: <cover.1288794124.git.jeremy.fitzhardinge@citrix.com>
On 11/03/2010 07:59 AM, Jeremy Fitzhardinge wrote:
>
> - with an unmodified struct spinlock, it can check to see if
> head == tail after unlock; if not, then there's someone else
> trying to lock, and we can do a kick. Unfortunately this
> generates very high level of redundant kicks, because the
> waiting CPU might not have blocked yet (which is the common
> case)
>
How high is "very high" here -- most of the time (so that any mitigation
on the slow patch is useless)?
-hpa
next prev parent reply other threads:[~2010-11-12 22:14 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-03 14:59 [PATCH 00/20] x86: ticket lock rewrite and paravirtualization Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 01/20] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2010-11-13 9:57 ` Américo Wang
2010-11-15 19:36 ` Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 02/20] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2010-11-03 15:11 ` Eric Dumazet
2010-11-03 15:38 ` Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 03/20] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2010-11-03 15:13 ` Eric Dumazet
2010-11-03 18:00 ` Jeremy Fitzhardinge
2010-11-13 10:05 ` Américo Wang
2010-11-13 22:34 ` Paolo Bonzini
2010-11-15 19:38 ` Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 04/20] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2010-11-12 12:19 ` Srivatsa Vaddagiri
2010-11-12 16:27 ` Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 05/20] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 06/20] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2010-11-13 10:17 ` Américo Wang
2010-11-13 10:48 ` Eric Dumazet
2010-11-15 19:39 ` Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 07/20] x86/spinlocks: replace pv spinlocks with pv ticketlocks Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 08/20] x86/ticketlock: collapse a layer of functions Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 09/20] xen/pvticketlock: Xen implementation for PV ticket locks Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 10/20] x86/pvticketlock: keep count of blocked cpus Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 11/20] x86/pvticketlock: use callee-save for lock_spinning Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 12/20] x86/pvticketlock: use callee-save for unlock_kick as well Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 13/20] x86/pvticketlock: make sure unlock is seen by everyone before checking waiters Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 14/20] x86/ticketlock: loosen ordering restraints on unlock Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 15/20] x86/ticketlock: prevent compiler reordering into locked region Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 16/20] x86/ticketlock: don't inline _spin_unlock when using paravirt spinlocks Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 17/20] x86/ticketlock: clarify barrier in arch_spin_lock Jeremy Fitzhardinge
2010-11-03 14:59 ` [PATCH 18/20] x86/ticketlock: remove .slock Jeremy Fitzhardinge
2010-11-03 15:00 ` [PATCH 19/20] x86/ticketlocks: use overlapping read to eliminate mb() Jeremy Fitzhardinge
2010-11-03 15:00 ` [PATCH 20/20] x86/ticketlock: rename ticketpair to head_tail Jeremy Fitzhardinge
2010-11-12 22:12 ` H. Peter Anvin [this message]
2010-11-12 22:17 ` [PATCH 00/20] x86: ticket lock rewrite and paravirtualization Jeremy Fitzhardinge
2010-11-12 22:20 ` H. Peter Anvin
2010-11-15 20:00 ` Jeremy Fitzhardinge
2010-11-15 20:03 ` H. Peter Anvin
2010-11-15 20:14 ` Peter Zijlstra
2010-11-15 21:02 ` Jeremy Fitzhardinge
2010-11-15 21:08 ` Peter Zijlstra
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