On Tue, Aug 30, 2005 at 04:34:04PM +0530, raja wrote: > In kernel code the macros likely() and unlikely() are frequently > used.Would you please tell me wht those macros will actually perform?. > thanking you, See http://lxr.linux.no/source/include/linux/compiler.h#L60 for the definition. As you can see, it uses __builtin_expect(). If you look that up in the GCC manual (installed on your pc, but also available online at http://gcc.gnu.org/onlinedocs/gcc-3.4.4/gcc/Other-Builtins.html ) you will find that it is used to provide the compiler with branch prediction information. If you have no idea what branch prediction is, then don't use likely() and unlikely() and let the compiler figure out what's best. Erik -- Erik Mouw J.A.K.Mouw@xxxxxxxxxxxxxx mouw@xxxxxxxxxxxx
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