Messages in this thread Patch in this message | | | From | Pavel Begunkov <> | Subject | [PATCH] fs: optimise kiocb_set_rw_flags() | Date | Fri, 17 Jan 2020 04:16:41 +0300 |
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kiocb_set_rw_flags() generates a poor code with several memory writes and a lot of jumps. Help compilers to optimise it.
Tested with gcc 9.2 on x64-86, and as a result, it its output now is a plain code without jumps accumulating in a register before a memory write.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> --- include/linux/fs.h | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/include/linux/fs.h b/include/linux/fs.h index 98e0349adb52..c3db8c80aed4 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -3402,22 +3402,27 @@ static inline int iocb_flags(struct file *file) static inline int kiocb_set_rw_flags(struct kiocb *ki, rwf_t flags) { + int kiocb_flags = 0; + if (unlikely(flags & ~RWF_SUPPORTED)) return -EOPNOTSUPP; if (flags & RWF_NOWAIT) { if (!(ki->ki_filp->f_mode & FMODE_NOWAIT)) return -EOPNOTSUPP; - ki->ki_flags |= IOCB_NOWAIT; + kiocb_flags |= IOCB_NOWAIT; } if (flags & RWF_HIPRI) - ki->ki_flags |= IOCB_HIPRI; + kiocb_flags |= IOCB_HIPRI; if (flags & RWF_DSYNC) - ki->ki_flags |= IOCB_DSYNC; + kiocb_flags |= IOCB_DSYNC; if (flags & RWF_SYNC) - ki->ki_flags |= (IOCB_DSYNC | IOCB_SYNC); + kiocb_flags |= (IOCB_DSYNC | IOCB_SYNC); if (flags & RWF_APPEND) - ki->ki_flags |= IOCB_APPEND; + kiocb_flags |= IOCB_APPEND; + + if (kiocb_flags) + ki->ki_flags |= kiocb_flags; return 0; } -- 2.24.0
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