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 17:53:35 -0500 [thread overview]
Message-ID: <20050325225335.GA12669@nevyn.them.org> (raw)
In-Reply-To: <424494AC.7020407@c2micro.com>
On Fri, Mar 25, 2005 at 02:46:04PM -0800, Ed Martini wrote:
> Daniel Jacobowitz wrote:
>
> >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.
> >
> >
> Yes, but in the case where R10000_LLSC_WAR is true, but cpu_has_llsc
> returns false there are still two wasted tests, and two blocks of code
> that the compiler can't optimize out.
Not only is cpu_has_llsc often a constant, R10000_LLSC_WAR will never
be true if the CPU does not have LL/SC.
--
Daniel Jacobowitz
CodeSourcery, LLC
prev parent reply other threads:[~2005-03-25 22:53 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
2005-03-25 22:46 ` Ed Martini
2005-03-25 22:53 ` Daniel Jacobowitz [this message]
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