From: Eric Dumazet <eric.dumazet@gmail.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>,
"H. Peter Anvin" <hpa@zytor.com>,
Linux Virtualization <virtualization@lists.linux-foundation.org>,
Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>,
Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Subject: Re: [PATCH 03/20] x86/ticketlock: Use C for __ticket_spin_unlock
Date: Wed, 03 Nov 2010 16:13:38 +0100 [thread overview]
Message-ID: <1288797218.2511.143.camel@edumazet-laptop> (raw)
In-Reply-To: <20092775a9df07a5a75820ac250194b535279d51.1288794124.git.jeremy.fitzhardinge@citrix.com>
Le mercredi 03 novembre 2010 à 10:59 -0400, Jeremy Fitzhardinge a
écrit :
> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
>
> If we don't need to use a locked inc for unlock, then implement it in C.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> ---
> arch/x86/include/asm/spinlock.h | 33 ++++++++++++++++++---------------
> 1 files changed, 18 insertions(+), 15 deletions(-)
>
> diff --git a/arch/x86/include/asm/spinlock.h b/arch/x86/include/asm/spinlock.h
> index 6711d36..082990a 100644
> --- a/arch/x86/include/asm/spinlock.h
> +++ b/arch/x86/include/asm/spinlock.h
> @@ -33,9 +33,23 @@
> * On PPro SMP or if we are using OOSTORE, we use a locked operation to unlock
> * (PPro errata 66, 92)
> */
> -# define UNLOCK_LOCK_PREFIX LOCK_PREFIX
> +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock)
> +{
> + if (sizeof(lock->tickets.head) == sizeof(u8))
> + asm (LOCK_PREFIX "incb %0"
> + : "+m" (lock->tickets.head) : : "memory");
> + else
> + asm (LOCK_PREFIX "incw %0"
> + : "+m" (lock->tickets.head) : : "memory");
> +
> +}
> #else
> -# define UNLOCK_LOCK_PREFIX
> +static __always_inline void __ticket_unlock_release(struct arch_spinlock *lock)
> +{
> + barrier();
technically speaking, it should be : smp_wmb()
> + lock->tickets.head++;
> + barrier();
Not sure you need this one.
> +}
> #endif
>
next prev parent reply other threads:[~2010-11-03 15:13 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 [this message]
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 ` [PATCH 00/20] x86: ticket lock rewrite and paravirtualization H. Peter Anvin
2010-11-12 22:17 ` 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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