From: Daniel Jacobowitz <dan@debian.org>
To: Ed Martini <martini@c2micro.com>
Cc: linux-mips@linux-mips.org
Subject: Re: Observations on LLSC and SMP
Date: Fri, 25 Mar 2005 14:37:59 -0500 [thread overview]
Message-ID: <20050325193759.GA23046@nevyn.them.org> (raw)
In-Reply-To: <42446555.6090005@c2micro.com>
On Fri, Mar 25, 2005 at 11:24:05AM -0800, Ed Martini wrote:
> 1. If the first part of the if were an ifdef instead it would result in
> a code size reduction as well as a runtime performance gain.
You should spend a little time playing with an optimizing compiler.
They're capable of working out when a condition will always be false.
> 2. In atomic.h the "C lang stuff" is wrapped with a spinlock. In the
> SMP case the spinlock will result in code that contains ll and sc
> instructions, so I infer that there are no SMP system configs that use
> CPUs that don't have the ll and sc instructions.
That's correct. It is not practical to implement SMP without a mutex
primitive.
--
Daniel Jacobowitz
CodeSourcery, LLC
next prev parent reply other threads:[~2005-03-25 19:37 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-10 23:42 initrd problem Ed Martini
2005-03-11 0:41 ` Kumba
2005-03-14 11:01 ` Ralf Baechle
2005-03-15 22:37 ` Ed Martini
2005-03-16 12:06 ` Ralf Baechle
2005-03-17 0:23 ` initrd/initramfs problem Ed Martini
2005-03-25 19:24 ` Observations on LLSC and SMP Ed Martini
2005-03-25 19:37 ` Daniel Jacobowitz [this message]
2005-03-25 22:46 ` Ed Martini
2005-03-25 22:53 ` Daniel Jacobowitz
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