From: Ralf Baechle <ralf@linux-mips.org>
To: Thomas Koeller <thomas@koeller.dyndns.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>,
wim@iguana.be, linux-kernel@vger.kernel.org,
linux-mips@linux-mips.org
Subject: Re: [PATCH] Added MIPS RM9K watchdog driver
Date: Sat, 12 Aug 2006 23:41:00 +0100 [thread overview]
Message-ID: <20060812224100.GA9043@linux-mips.org> (raw)
In-Reply-To: <200608121806.02844.thomas@koeller.dyndns.org>
On Sat, Aug 12, 2006 at 06:06:02PM +0200, Thomas Koeller wrote:
> > > + while (1) continue;
> >
> > cpu_relax();
>
> I tried to find out about the purpose of cpu_relax(). On MIPS, at least,
> it maps to barrier(). I do not quite understand why I would need a
> barrier() in this place. Would you, or someone else, care to
> enlighten me?
Busy wait loops are meant to be filled with cpu_relax() in Linux. On
processors like the Pentium 4 this expands into something that keeps
the CPU from consuming excessive amounts of energy for just twiddling
thumbs and probably also CPU dependant. On MIPS cpu_relax() so far is
meaningless and therfore just defined as barrier().
Ralf
next prev parent reply other threads:[~2006-08-12 22:41 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-08-10 21:19 [PATCH] Added MIPS RM9K watchdog driver thomas
2006-08-11 20:07 ` Alan Cox
2006-08-12 16:06 ` Thomas Koeller
2006-08-12 22:41 ` Ralf Baechle [this message]
2006-08-12 17:45 ` Thomas Koeller
2006-08-12 20:43 ` Alan Cox
2006-08-11 20:56 ` Dave Jones
2006-08-11 23:49 ` Thomas Koeller
2006-08-11 22:06 ` Oleg Verych
2006-08-12 0:06 ` Dave Jones
2006-08-12 0:22 ` Ralf Baechle
2006-08-14 14:14 ` Joseph Fannin
2006-08-14 15:30 ` Sam Ravnborg
2006-08-14 16:21 ` Randy.Dunlap
2006-08-14 16:26 ` Dave Jones
2006-08-14 16:27 ` Roland Dreier
2006-08-14 15:50 ` Wim Van Sebroeck
2006-08-14 19:55 ` [PATCH] " Thomas Koeller
2006-08-14 17:25 ` [PATCH] Added " Luca
-- strict thread matches above, loose matches on Subject: below --
2006-11-01 18:46 Wim Van Sebroeck
2006-11-01 18:50 ` Ralf Baechle
2006-11-01 19:11 ` Wim Van Sebroeck
2006-11-01 20:43 ` Sam Ravnborg
2006-11-02 6:11 ` Randy Dunlap
2006-11-02 14:04 ` Ralf Baechle
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