On Sun, Nov 18, 2018 at 08:02:18PM +0800, Yafang Shao wrote: > This little adjustment on bitwise operation could make the code a little > faster. > As write_iter is used in lots of critical path, so this code change is > useful for performance.
Did you check the before/after code generation with this patch applied? $ diff -u before.S after.S --- before.S 2018-11-18 07:11:48.031096768 -0500 +++ after.S 2018-11-18 07:11:36.883069103 -0500 @@ -1,5 +1,5 @@ -before.o: file format elf32-i386 +after.o: file format elf32-i386 Disassembly of section .text: with gcc 8.2.0, I see no difference, indicating that the compiler already makes this optimisation.
