[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: likely/unlikely macro.



Shinpei Kato wrote:
> Thank you for your reply.
> 
> So, for example, the expression "if (likely(prev != next))" is same as "if
> ((prev != next) == 1)", isn't it?
More correct would be next:
if (gcc support __builtin_expect) {
	we do nothing and likely(prev!=next) => __builtin_expect((prev!=next),1)
	then gcc use this information for optimization, this branch of code 
would be more otimized then alternatives.
} else {
	likely(prev!=next) => (prev != next)
	so we don't break compilation and don't do any optimization.
}
> Then, unlikely is opposite of that.
yes
[snip]
		Best regards. Ruslan.

--
Kernelnewbies: Help each other learn about the Linux kernel.
Archive:       http://mail.nl.linux.org/kernelnewbies/
FAQ:           http://kernelnewbies.org/faq/