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From: Kyle Moffett <mrmacman_g4@mac.com>
To: Ingo Molnar <mingo@elte.hu>
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: Sun, 20 Mar 2005 03:01:11 -0500	[thread overview]
Message-ID: <24e1c77a699dcab771a0280df69d44eb@mac.com> (raw)
In-Reply-To: <20050319163128.GB28958@elte.hu>

On Mar 19, 2005, at 11:31, Ingo Molnar wrote:
>> What about allowing only as many concurrent readers as there are CPUs?
>
> since a reader may be preempted by a higher prio task, there is no
> linear relationship between CPU utilization and the number of readers
> allowed. You could easily end up having all the nr_cpus readers
> preempted on one CPU. It gets pretty messy

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

Cheers,
Kyle Moffett

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PGP+++ t+(+++) 5 X R? tv-(--) b++++(++) DI+ D+ G e->++++$ h!*()>++$ r  
!y?(-)
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  reply	other threads:[~2005-03-20  8:01 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 [this message]
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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