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From: Helge Hafting <helgehaf@aitel.hist.no>
To: ptb@it.uc3m.es
Cc: linux-kernel@vger.kernel.org
Subject: Re: recursive spinlocks. Shoot.
Date: Mon, 19 May 2003 12:29:16 +0200	[thread overview]
Message-ID: <3EC8B1FC.9080106@aitel.hist.no> (raw)
In-Reply-To: 200305181724.h4IHOHU24241@oboe.it.uc3m.es

Peter T. Breuer wrote:

> Hey, that's not bad for a small change! 50% of potential programming
> errors sent to the dustbin without ever being encountered.

Then you replace errors with inefficiency - nobody discovers that
you needlessly take a lock twice.  They notice OOPSes though, the
lock gurus can then debug it.

Trading performance for simplicity is ok in some cases, but I have a strong
felling this isn't one of them.  Consider how people optimize locking
by shaving off a single cycle when they can, and try to avoid
locking as much as possible for that big smp scalability.

This is something better done right - people should just take the
trouble.

Helge Hafting


  parent reply	other threads:[~2003-05-19 10:17 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-05-18  9:21 recursive spinlocks. Shoot Peter T. Breuer
2003-05-18 16:30 ` Martin J. Bligh
2003-05-18 16:35   ` William Lee Irwin III
2003-05-18 16:49     ` Arjan van de Ven
2003-05-18 16:54       ` William Lee Irwin III
2003-05-18 17:14         ` Martin J. Bligh
2003-05-18 17:24     ` Peter T. Breuer
2003-05-18 22:34       ` David Woodhouse
2003-05-19 13:37         ` Peter T. Breuer
2003-05-19 13:45           ` Jens Axboe
2003-05-19 13:47           ` Arjan van de Ven
     [not found]           ` <mailman.1053352200.24653.linux-kernel2news@redhat.com>
2003-05-19 23:54             ` Pete Zaitcev
2003-05-20  0:03               ` viro
2003-05-20  0:03               ` Johannes Erdfelt
2003-05-20  3:12         ` Robert White
2003-05-20 11:59           ` Helge Hafting
2003-05-20 12:23             ` Richard B. Johnson
2003-05-20 21:05               ` Robert White
2003-05-20 21:42                 ` Richard B. Johnson
2003-05-20 23:06                   ` Robert White
2003-05-21 14:01                     ` Richard B. Johnson
2003-05-21 21:56                       ` Robert White
2003-05-22  0:13                         ` viro
2003-05-22  0:32                           ` Robert White
2003-05-22  0:46                         ` Carl-Daniel Hailfinger
2003-05-21  5:48                   ` Nikita Danilov
2003-05-22  1:00           ` Rik van Riel
2003-05-22  3:11             ` Robert White
2003-05-22  4:04               ` Nick Piggin
2003-05-22  4:42                 ` Peter T. Breuer
2003-05-22  5:09                   ` Nick Piggin
2003-05-23  0:19                 ` Robert White
2003-05-23  7:22                   ` Nikita Danilov
2003-05-23  9:07                     ` Helge Hafting
2003-05-23 12:18                     ` William Lee Irwin III
2003-05-24  2:39                       ` Robert White
2003-05-28 16:50                         ` Timothy Miller
2003-05-19  2:05       ` Kevin O'Connor
2003-05-19  6:19       ` Jan Hudec
2003-05-19 10:29       ` Helge Hafting [this message]
2003-05-19 11:37         ` Nikita Danilov
2003-05-22  1:21           ` Daniel Phillips
2003-05-19 14:28       ` Martin J. Bligh
2003-05-18 18:13 ` Davide Libenzi
     [not found] <20030518182010$0541@gated-at.bofh.it>
2003-05-18 19:09 ` Peter T. Breuer
2003-05-18 19:31   ` Davide Libenzi
2003-05-18 19:49     ` Peter T. Breuer
2003-05-18 20:13       ` Davide Libenzi
2003-05-19 20:47   ` Jan Hudec
     [not found] <20030518202013$5297@gated-at.bofh.it>
2003-05-18 23:15 ` Peter T. Breuer
2003-05-18 23:26   ` Davide Libenzi
2003-05-19 12:48     ` Peter T. Breuer
2003-05-19 17:15       ` Davide Libenzi
2003-05-19 17:27         ` Peter T. Breuer
2003-05-19 17:57           ` Alan Cox
2003-05-19 19:51         ` Peter T. Breuer
2003-05-19 20:22   ` Robert White
     [not found] <20030520231013$3d77@gated-at.bofh.it>
2003-05-21 14:16 ` Peter T. Breuer

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