2 messages, 2 authors, 2008-02-18 · open the first message on its own page
From: <hidden>
Date: 2008-02-18 18:14:12
On Mon, 18 Feb 2008 14:27:10 GMT, David Howells said:
__builtin_expect() is useful on FRV where you _have_ to give each branch and conditional branch instruction a measure of probability whether the branch will be taken.
What does gcc do the 99.998% of the time we don't have likely/unlikely coded?
From: Arjan van de Ven <hidden>
Date: 2008-02-18 18:34:53
On Mon, 18 Feb 2008 13:11:06 -0500 Valdis.Kletnieks@vt.edu wrote:
On Mon, 18 Feb 2008 14:27:10 GMT, David Howells said:quoted
__builtin_expect() is useful on FRV where you _have_ to give each branch and conditional branch instruction a measure of probability whether the branch will be taken.What does gcc do the 99.998% of the time we don't have likely/unlikely coded?
see Andi's email. It gets the exact same hints that 95%+ of the kernels unlikely/likely get you, because the heuristics in it are usually the same as the kernel programmers heuristics. -- If you want to reach me at my work email, use arjan@linux.intel.com For development, discussion and tips for power savings, visit http://www.lesswatts.org