Re: Patch: linux-2.5.29 __downgrade_write() for CONFIG_RWSEM_GENERIC_SPINLOCK

[Roman Zippel <zippel@linux-m68k.org>]

Hi,

On Mon, 29 Jul 2002, David Howells wrote:

> > You don't really need that extra argument, testing sem->activity should do
> > the same job.
> > If you exchange the wakewrite (or sem->activity) test and the
> > waiter->flags you can fold it into the next test (this means all the extra
> > work would only be done, if we have a writer waiting at the top).
>
> The reason for doing it this way is that it allows the compiler to discard
> parts of the function when inlining it since the value is set at compile time
> rather than being worked out at runtime. The value itself should be
> disappeared entirely by the compiler.

Did you look at the code? gcc should be able to optimize that itself.

bye, Roman