From: Peter Zijlstra <peterz@infradead.org>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: 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>
Subject: Re: [PATCH RFC 02/12] x86/ticketlock: convert spin loop to C
Date: Mon, 02 Aug 2010 17:07:19 +0200 [thread overview]
Message-ID: <1280761639.1923.213.camel@laptop> (raw)
In-Reply-To: <cf01e01095f802dc5082e82a8e96c84903e929a6.1279328276.git.jeremy.fitzhardinge@citrix.com>
On Fri, 2010-07-16 at 18:03 -0700, Jeremy Fitzhardinge wrote:
> + register union {
> + struct __raw_tickets tickets;
> + unsigned short slock;
> + } inc = { .slock = 1 << TICKET_SHIFT };
register arch_spinlock_t inc = { .tickets = { .head = 1, .tail = 0 } };
>From a quick look you can basically replace all TICKET_SHIFT usage (1 <<
TICKET_SHIFT) with such a constant.
[ Also, does gcc really listen to the register hint these days? ]
> + asm volatile (LOCK_PREFIX "xaddw %w0, %1\n"
> + : "+Q" (inc), "+m" (lock->slock) : : "memory", "cc");
"+Q" (inc->slock)
> + for (;;) {
> + if (inc.tickets.head == inc.tickets.tail)
> + return;
> + cpu_relax();
> + inc.tickets.head = ACCESS_ONCE(lock->tickets.head);
> + }
> + barrier(); /* make sure nothing creeps before the lock is taken */
> }
How will it ever get to that barrier() ?
next prev parent reply other threads:[~2010-08-02 15:07 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-17 1:03 [PATCH RFC 00/12] X86 ticket lock cleanups and improvements Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 03/12] x86/ticketlock: Use C for __ticket_spin_unlock Jeremy Fitzhardinge
2010-07-20 15:38 ` [Xen-devel] " Konrad Rzeszutek Wilk
2010-07-20 16:17 ` Jeremy Fitzhardinge
2010-08-06 17:47 ` H. Peter Anvin
2010-08-06 20:03 ` Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 04/12] x86/ticketlock: make large and small ticket versions of spin_lock the same Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 08/12] x86/ticketlock: collapse a layer of functions Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 12/12] x86/pvticketlock: use callee-save for unlock_kick as well Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 09/12] xen/pvticketlock: Xen implementation for PV ticket locks Jeremy Fitzhardinge
2010-09-26 11:39 ` Srivatsa Vaddagiri
2010-09-26 22:34 ` Jeremy Fitzhardinge
2011-01-18 16:27 ` Srivatsa Vaddagiri
2011-01-19 1:28 ` Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 01/12] x86/ticketlock: clean up types and accessors Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 06/12] x86/ticketlock: make __ticket_spin_trylock common Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 11/12] x86/pvticketlock: use callee-save for lock_spinning Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 07/12] x86/spinlocks: replace pv spinlocks with pv ticketlocks Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 02/12] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
2010-08-02 15:07 ` Peter Zijlstra [this message]
2010-08-02 15:17 ` Jeremy Fitzhardinge
2010-08-06 12:43 ` Jan Beulich
2010-08-06 14:53 ` Jeremy Fitzhardinge
2010-08-06 20:17 ` H. Peter Anvin
2010-08-06 20:33 ` Jeremy Fitzhardinge
2010-08-06 21:09 ` H. Peter Anvin
2010-08-06 22:03 ` Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 10/12] x86/pvticketlock: keep count of blocked cpus Jeremy Fitzhardinge
2010-08-03 8:32 ` Peter Zijlstra
2010-08-03 9:44 ` Nick Piggin
2010-08-03 15:45 ` Jeremy Fitzhardinge
2010-07-17 1:03 ` [PATCH RFC 05/12] x86/ticketlock: make __ticket_spin_lock common Jeremy Fitzhardinge
-- strict thread matches above, loose matches on Subject: below --
2010-07-03 0:06 [PATCH RFC 02/12] x86/ticketlock: convert spin loop to C Jeremy Fitzhardinge
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1280761639.1923.213.camel@laptop \
--to=peterz@infradead.org \
--cc=JBeulich@novell.com \
--cc=avi@redhat.com \
--cc=jeremy@goop.org \
--cc=linux-kernel@vger.kernel.org \
--cc=npiggin@suse.de \
--cc=xen-devel@lists.xensource.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox