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From: One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>
To: Khalid Aziz <khalid.aziz@oracle.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>,
	tglx@linutronix.de, Ingo Molnar <mingo@kernel.org>,
	peterz@infradead.org, akpm@linux-foundation.org,
	andi.kleen@intel.com, rob@landley.net, viro@zeniv.linux.org.uk,
	oleg@redhat.com, linux-kernel@vger.kernel.org
Subject: Re: [RFC] [PATCH] Pre-emption control for userspace
Date: Tue, 4 Mar 2014 22:23:56 +0000	[thread overview]
Message-ID: <20140304222356.41c55bbc@alan.etchedpixels.co.uk> (raw)
In-Reply-To: <53164824.3000704@oracle.com>

Obvious bug

| Usage model is a thread mmaps this file during initialization. It then
| writes a 1 to the mmap'd file after it grabs the lock in its critical
| section where it wants immunity from pre-emption.

You need to write it first or you can be pre-empted taking the lock
before asking for immunity.

Presumably you could equally use something to group tasks (say a control
group of some form) and implement voluntary pre-emption within the group
only when in user space. Ie they only pre-empt each other by yielding but
they can be pre-empted by other tasks outside the group ?


  reply	other threads:[~2014-03-04 22:25 UTC|newest]

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-03-03 18:07 [RFC] [PATCH] Pre-emption control for userspace Khalid Aziz
2014-03-03 21:51 ` Davidlohr Bueso
2014-03-03 23:29   ` Khalid Aziz
2014-03-04 13:56 ` Oleg Nesterov
2014-03-04 17:44   ` Khalid Aziz
2014-03-04 18:38     ` Al Viro
2014-03-04 19:01       ` Khalid Aziz
2014-03-04 19:03     ` Oleg Nesterov
2014-03-04 20:14       ` Khalid Aziz
2014-03-05 14:38         ` Oleg Nesterov
2014-03-05 16:12           ` Oleg Nesterov
2014-03-05 17:10             ` Khalid Aziz
2014-03-04 21:12 ` H. Peter Anvin
2014-03-04 21:39   ` Khalid Aziz
2014-03-04 22:23     ` One Thousand Gnomes [this message]
2014-03-04 22:44       ` Khalid Aziz
2014-03-05  0:39         ` Thomas Gleixner
2014-03-05  0:51           ` Andi Kleen
2014-03-05 11:10             ` Peter Zijlstra
2014-03-05 17:29               ` Khalid Aziz
2014-03-05 19:58               ` Khalid Aziz
2014-03-06  9:57                 ` Peter Zijlstra
2014-03-06 16:08                   ` Khalid Aziz
2014-03-06 11:14                 ` Thomas Gleixner
2014-03-06 16:32                   ` Khalid Aziz
2014-03-05 14:54             ` Oleg Nesterov
2014-03-05 15:56               ` Andi Kleen
2014-03-05 16:36                 ` Oleg Nesterov
2014-03-05 17:22                   ` Khalid Aziz
2014-03-05 23:13                     ` David Lang
2014-03-05 23:48                       ` Khalid Aziz
2014-03-05 23:56                         ` H. Peter Anvin
2014-03-06  0:02                           ` Khalid Aziz
2014-03-06  0:13                             ` H. Peter Anvin
2014-03-05 23:59                         ` David Lang
2014-03-06  0:17                           ` Khalid Aziz
2014-03-06  0:36                             ` David Lang
2014-03-06  1:22                               ` Khalid Aziz
2014-03-06 14:23                                 ` David Lang
2014-03-06 12:13             ` Kevin Easton
2014-03-06 13:59               ` Peter Zijlstra
2014-03-06 22:41                 ` Andi Kleen
2014-03-06 14:25               ` David Lang
2014-03-06 16:12                 ` Khalid Aziz
2014-03-06 13:24   ` Rasmus Villemoes
2014-03-06 13:34     ` Peter Zijlstra
2014-03-06 13:45       ` Rasmus Villemoes
2014-03-06 14:02         ` Peter Zijlstra
2014-03-06 14:33           ` Thomas Gleixner
2014-03-06 14:34             ` H. Peter Anvin
2014-03-06 14:04         ` Thomas Gleixner
2014-03-25 17:17 ` [PATCH v2] " Khalid Aziz
2014-03-25 17:44   ` Andrew Morton
2014-03-25 17:56     ` Khalid Aziz
2014-03-25 18:14       ` Andrew Morton
2014-03-25 17:46   ` Oleg Nesterov
2014-03-25 17:59     ` Khalid Aziz
2014-03-25 18:20   ` Andi Kleen
2014-03-25 18:47     ` Khalid Aziz
2014-03-25 19:47       ` Andi Kleen
2014-03-25 18:59   ` Eric W. Biederman
2014-03-25 19:15     ` Khalid Aziz
2014-03-25 20:31       ` Eric W. Biederman
2014-03-25 21:37         ` Khalid Aziz
2014-03-26  6:03     ` Mike Galbraith
2014-03-25 23:01 ` [RFC] [PATCH] " Davidlohr Bueso
2014-03-25 23:29   ` Khalid Aziz

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