On Tue, Mar 31, 2015 at 8:24 AM, Boaz Harrosh <b...@plexistor.com> wrote: > On 03/31/2015 06:17 PM, Dan Williams wrote: >> On Tue, Mar 31, 2015 at 6:27 AM, Boaz Harrosh <b...@plexistor.com> wrote: >>> >>> Some error checks had unlikely some did not. Put unlikely >>> on all error handling paths. >>> (I like unlikely for error paths specially for readability) >> >> "unlikely()" is not a readability hint, it's specifically for branches >> that profiling shows adding it makes a difference. Just delete them >> all until profiling show they make a difference. They certainly don't >> make a difference in the slow paths. >> > > Why?
Because the compiler and cpu already does a decent job, and if you get the frequency wrong it can hurt performance [1]. It's pre-mature optimization to sprinkle them around, especially in slow paths. [1]: https://lwn.net/Articles/420019/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
