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| author | Yu Ma <yu.ma@intel.com> | 2024-07-17 10:50:17 -0400 |
|---|---|---|
| committer | Al Viro <viro@zeniv.linux.org.uk> | 2024-10-07 13:34:41 -0400 |
| commit | c9a3019603b8a8519f1b6d8ae0059bcb2965f8fe (patch) | |
| tree | 1bf67638f836dbbad565c90b35cf96f4d95936a1 /fs/file.c | |
| parent | 52732bb9abc9ee5b82ed62edef51be4a255fc78a (diff) | |
| download | lwn-c9a3019603b8a8519f1b6d8ae0059bcb2965f8fe.tar.gz lwn-c9a3019603b8a8519f1b6d8ae0059bcb2965f8fe.zip | |
fs/file.c: conditionally clear full_fds
64 bits in open_fds are mapped to a common bit in full_fds_bits. It is very
likely that a bit in full_fds_bits has been cleared before in
__clear_open_fds()'s operation. Check the clear bit in full_fds_bits before
clearing to avoid unnecessary write and cache bouncing. See commit fc90888d07b8
("vfs: conditionally clear close-on-exec flag") for a similar optimization.
take stock kernel with patch 1 as baseline, it improves pts/blogbench-1.1.0
read for 13%, and write for 5% on Intel ICX 160 cores configuration with
v6.10-rc7.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Yu Ma <yu.ma@intel.com>
Link: https://lore.kernel.org/r/20240717145018.3972922-3-yu.ma@intel.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs/file.c')
| -rw-r--r-- | fs/file.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/fs/file.c b/fs/file.c index 90b8aa2378cc..36c5089812f5 100644 --- a/fs/file.c +++ b/fs/file.c @@ -264,7 +264,9 @@ static inline void __set_open_fd(unsigned int fd, struct fdtable *fdt) static inline void __clear_open_fd(unsigned int fd, struct fdtable *fdt) { __clear_bit(fd, fdt->open_fds); - __clear_bit(fd / BITS_PER_LONG, fdt->full_fds_bits); + fd /= BITS_PER_LONG; + if (test_bit(fd, fdt->full_fds_bits)) + __clear_bit(fd, fdt->full_fds_bits); } static inline bool fd_is_open(unsigned int fd, const struct fdtable *fdt) |