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From: Ingo Molnar <mingo@elte.hu>
To: Bill Huey <bhuey@lnxw.com>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>,
	dipankar@in.ibm.com, shemminger@osdl.org, akpm@osdl.org,
	torvalds@osdl.org, rusty@au1.ibm.com, tgall@us.ibm.com,
	jim.houston@comcast.net, manfred@colorfullife.com, gh@us.ibm.com,
	linux-kernel@vger.kernel.org
Subject: Re: Real-Time Preemption and RCU
Date: Fri, 18 Mar 2005 17:02:29 +0100	[thread overview]
Message-ID: <20050318160229.GC25485@elte.hu> (raw)
In-Reply-To: <20050318131729.GB5107@nietzsche.lynx.com>


* Bill Huey <bhuey@lnxw.com> wrote:

> I'd like to note another problem. Mingo's current implementation of
> rt_mutex (super mutex for all blocking synchronization) is still
> missing reader counts and something like that would have to be
> implemented if you want to do priority inheritance over blocks.

i really have no intention to allow multiple readers for rt-mutexes. We
got away with that so far, and i'd like to keep it so. Imagine 100
threads all blocked in the same critical section (holding the read-lock)
when a highprio writer thread comes around: instant 100x latency to let
all of them roll forward. The only sane solution is to not allow
excessive concurrency. (That limits SMP scalability, but there's no
other choice i can see.)

	Ingo

  parent reply	other threads:[~2005-03-18 16:05 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-03-18  0:20 Real-Time Preemption and RCU Paul E. McKenney
2005-03-18  7:49 ` Ingo Molnar
2005-03-18 16:43   ` Paul E. McKenney
2005-03-18 17:11     ` Ingo Molnar
2005-03-18 17:29       ` Paul E. McKenney
2005-03-18 20:35       ` Paul E. McKenney
2005-03-18 22:22         ` Paul E. McKenney
2005-03-19  0:48           ` Paul E. McKenney
2005-03-18  8:44 ` Ingo Molnar
2005-03-18  9:04 ` Ingo Molnar
2005-03-18  9:38   ` Ingo Molnar
2005-03-18  9:13 ` Ingo Molnar
2005-03-18  9:28   ` Ingo Molnar
2005-03-18  9:53     ` Ingo Molnar
2005-03-18 15:33       ` Paul E. McKenney
2005-03-19  5:03     ` Manfred Spraul
2005-03-19 16:26       ` Ingo Molnar
2005-03-20  6:36         ` Manfred Spraul
2005-03-20  9:25           ` Thomas Gleixner
2005-03-20 16:57             ` Manfred Spraul
2005-03-20 21:38               ` Bill Huey
2005-03-20 21:59                 ` Bill Huey
2005-03-18 10:03 ` Ingo Molnar
2005-03-18 11:30   ` Ingo Molnar
2005-03-18 16:48     ` Esben Nielsen
2005-03-18 17:19       ` Ingo Molnar
2005-03-20 13:29         ` Esben Nielsen
2005-03-20 22:38           ` Paul E. McKenney
2005-03-20 23:23             ` Esben Nielsen
2005-03-22  5:53               ` Paul E. McKenney
2005-03-22  8:55                 ` Esben Nielsen
2005-03-22  9:20                   ` Ingo Molnar
2005-03-22 10:19                     ` Esben Nielsen
2005-03-23  5:40                   ` Paul E. McKenney
2005-03-23 11:44                     ` Esben Nielsen
2005-03-24  7:02                       ` Paul E. McKenney
2005-03-22 10:56           ` Ingo Molnar
2005-03-22 11:39             ` Esben Nielsen
2005-03-22 13:10               ` Ingo Molnar
2005-03-22 15:08                 ` Esben Nielsen
2005-03-18 15:48   ` Paul E. McKenney
2005-03-18 11:38 ` Ingo Molnar
2005-03-18 12:56 ` Bill Huey
2005-03-18 13:17   ` Bill Huey
2005-03-18 15:57     ` Paul E. McKenney
2005-03-18 16:02     ` Ingo Molnar [this message]
2005-03-18 16:55       ` Esben Nielsen
2005-03-22 10:04         ` Bill Huey
2005-03-22 10:17           ` Bill Huey
2005-03-22 10:34             ` Bill Huey
2005-03-22 10:38           ` Esben Nielsen
2005-03-18 22:26       ` Herbert Xu
2005-03-19 16:31         ` Ingo Molnar
2005-03-20  8:01           ` Kyle Moffett
2005-03-22  8:08             ` Ingo Molnar
2005-03-18 15:54   ` Paul E. McKenney
2005-03-18 15:58     ` Ingo Molnar
  -- strict thread matches above, loose matches on Subject: below --
2009-06-11 22:57 real-time preemption " James Huang

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