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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Avi Kivity <avi@redhat.com>, Darren Hart <dvhltc@us.ibm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	"Peter W. Morreale" <pmorreale@novell.com>,
	Rik van Riel <riel@redhat.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Gregory Haskins <ghaskins@novell.com>,
	Sven-Thorsten Dietrich <sdietrich@novell.com>,
	Chris Mason <chris.mason@oracle.com>,
	John Cooper <john.cooper@third-harmonic.com>,
	Chris Wright <chrisw@sous-sol.org>
Subject: Re: [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning
Date: Tue, 6 Apr 2010 17:54:15 +0100	[thread overview]
Message-ID: <20100406175415.3e4a57df@lxorguk.ukuu.org.uk> (raw)
In-Reply-To: <alpine.LFD.2.00.1004061809080.32352@localhost.localdomain>

> > IMO the best solution is to spin in userspace while the lock holder is
> > running, fall into the kernel when it is scheduled out.
> 
> That's just not realistic as user space has no idea whether the lock
> holder is running or not and when it's scheduled out without a syscall :)

Which is the real problem that wants addressing and can be addressed very
cheaply. That would bring us up to par with 1970s RTOS environments ;)

Alan

  parent reply	other threads:[~2010-04-06 16:51 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-04-05 20:23 [PATCH V2 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning Darren Hart
2010-04-05 20:23 ` [PATCH 1/6] futex: replace fshared and clockrt with combined flags Darren Hart
2010-04-05 20:23 ` [PATCH 2/6] futex: add futex_q static initializer Darren Hart
2010-04-05 20:23 ` [PATCH 3/6] futex: refactor futex_lock_pi_atomic Darren Hart
2010-04-05 20:23 ` [PATCH 4/6] futex: Add FUTEX_LOCK with optional adaptive spinning Darren Hart
2010-04-06 16:55   ` Thomas Gleixner
2010-04-07 17:26     ` Darren Hart
2010-04-07 19:59       ` Thomas Gleixner
2010-04-08  3:25         ` Darren Hart
2010-04-08 23:10           ` Peter W. Morreale
2010-04-09  5:41             ` Darren Hart
2010-04-09 13:13               ` Peter W. Morreale
2010-04-05 20:23 ` [PATCH 5/6] futex: handle timeout inside adaptive lock spin Darren Hart
2010-04-06  8:27   ` Thomas Gleixner
2010-04-07 17:31     ` Darren Hart
2010-04-07 18:44       ` Gregory Haskins
2010-04-07 23:15         ` Darren Hart
2010-04-05 20:23 ` [PATCH 6/6] futex: Add aggressive adaptive spinning argument to FUTEX_LOCK Darren Hart
2010-04-08  5:58   ` Darren Hart
2010-04-05 20:48 ` [PATCH V2^W V4 0/6][RFC] futex: FUTEX_LOCK with optional adaptive spinning Darren Hart
2010-04-05 21:15 ` [PATCH V2 " Avi Kivity
2010-04-05 21:54   ` Darren Hart
2010-04-05 22:21     ` Avi Kivity
2010-04-05 22:59       ` Darren Hart
2010-04-06 13:28         ` Avi Kivity
2010-04-06 13:35           ` Peter Zijlstra
2010-04-06 13:41             ` Avi Kivity
2010-04-06 14:09               ` Peter Zijlstra
2010-04-06 16:10                 ` Avi Kivity
2010-04-06 16:53                   ` Alan Cox
2010-04-06 13:51             ` Alan Cox
2010-04-06 15:28               ` Darren Hart
2010-04-06 16:06                 ` Avi Kivity
2010-04-06 16:14                   ` Thomas Gleixner
2010-04-06 16:20                     ` Avi Kivity
2010-04-07  6:18                       ` john cooper
2010-04-08  3:33                         ` Darren Hart
2010-04-09  5:52                           ` john cooper
2010-04-06 16:54                     ` Alan Cox [this message]
2010-04-06 18:15                       ` Thomas Gleixner
2010-04-06 16:44                 ` Alan Cox
2010-04-06 17:34                   ` Ulrich Drepper
2010-04-10 23:35                     ` Alan Cox
2010-04-10 23:53                       ` Ulrich Drepper
2010-04-06 19:31                   ` Thomas Gleixner
2010-04-06 20:02                     ` Ulrich Drepper
2010-04-06 23:16                       ` Thomas Gleixner
2010-04-06 23:36                         ` Darren Hart
2010-04-07  6:08                         ` drepper
2010-04-08  3:41                           ` Darren Hart
2010-04-08  4:29                             ` drepper
2010-04-07  5:33                     ` Avi Kivity
2010-04-06 21:22         ` Darren Hart
2010-04-05 23:15       ` Darren Hart
2010-04-05 23:29         ` Chris Wright
2010-04-06 13:30         ` Avi Kivity
2010-04-06  8:48   ` Peter Zijlstra
2010-04-06 14:47     ` Ulrich Drepper
2010-04-06 14:51       ` Peter Zijlstra
2010-04-06 15:33         ` Darren Hart
2010-04-06 15:37           ` Peter Zijlstra
2010-04-06 15:29 ` Peter Zijlstra

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