Re: drm/vmwgfx: Fix compat shader namespace

[Dan Carpenter <dan.carpenter@oracle.com>]

On Wed, Jul 09, 2014 at 11:31:45PM +0200, Thomas Hellström wrote:
> >Speaking of verbose, all the likely/unlikely annotations should be
> >removed.
> 
> Is this your personal opinion or has there been some kind of kernel
> developer agreement not to add this annotation and remove it from
> the kernel tree? If not, I prefer to keep it.

It obviously makes the code less readable.  It makes a small speedup if
the code is called 10000 times with the and the expected value is true
every time.  If more than 1 out of 10000 values is unexpected then it is
a slow down.

There are two rules of thumb for likely/unlikely:

	1) Don't use it in the drivers/ directory.
	2) Or don't use it without benchmarking it.

These are general rules, not mine.

In the olden days we used to use it more often but then people did
benchmarking and likely/unlikely annotations didn't make a single
measurable difference on normal benchmarks at all.  Maybe on a micro
benchmark.  Also perhaps in those days people hadn't done branch
profiling so we were getting a lot of unexpected conditions and the slow
downs were canceling the speed ups.

regards,
dan carpenter