[lkml]   [2005]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH] speed up on find_first_bit for i386 (let compiler do the work)
On Thu, 28 Jul 2005, Steven Rostedt wrote:

> I've been playing with different approaches, (still all hot cache
> though), and inspecting the generated code. It's not that the gcc
> generated code is always better for the normal case. But since it sees
> more and everything is not hidden in asm, it can optimise what is being
> used, and how it's used.

Since you're considering GCC-generated code for ffs(), ffz() and friends,
how about trying __builtin_ffs(), __builtin_clz() and __builtin_ctz() as
apropriate? Reasonably recent GCC may actually be good enough to use the
fastest code depending on the processor submodel selected.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-07-28 19:14    [from the cache]
©2003-2014 Jasper Spaans. hosted at Digital Ocean