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From: Ingo Molnar <mingo@elte.hu>
To: Kyle Moffett <mrmacman_g4@mac.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	rusty@au1.ibm.com, bhuey@lnxw.com, gh@us.ibm.com,
	tgall@us.ibm.com, jim.houston@comcast.net,
	linux-kernel@vger.kernel.org, torvalds@osdl.org, akpm@osdl.org,
	paulmck@us.ibm.com, manfred@colorfullife.com,
	shemminger@osdl.org, dipankar@in.ibm.com
Subject: Re: Real-Time Preemption and RCU
Date: Tue, 22 Mar 2005 09:08:00 +0100	[thread overview]
Message-ID: <20050322080800.GA9497@elte.hu> (raw)
In-Reply-To: <24e1c77a699dcab771a0280df69d44eb@mac.com>


* Kyle Moffett <mrmacman_g4@mac.com> wrote:

> One solution I can think of, although it bloats memory usage for
> many-way boxen, is to just have a table in the rwlock with one entry
> per cpu.  Each CPU would get one concurrent reader, others would need
> to sleep

yes, it bloats memory usage, and complicates PI quite significantly. 
We've been there and have done something similar to that in earlier -RT
patches - 64 'owner' entries in the lock already caused problems on 8K
stacks. 32 seemed to work but caused quite some bloat in data structure
sizes.

i'd rather live with some scalability bottleneck for now, in exchange of
a wastly easier to handle design. We can still complicate things later
on for better scalability, once all the other issues have been sorted
out.

	Ingo

  reply	other threads:[~2005-03-22  8:08 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
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 [this message]
2005-03-18 15:54   ` Paul E. McKenney
2005-03-18 15:58     ` Ingo Molnar
2009-06-11 22:57 real-time preemption " James Huang

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