Messages in this thread Patch in this message | | | Date | Sun, 18 Nov 2018 04:13:18 -0800 | From | Matthew Wilcox <> | Subject | Re: [PATCH] mm/filemap.c: minor optimization in write_iter file operation |
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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.
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