| Message ID | 20240614163416.728752-3-yu.ma@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fs/file.c: optimize the critical section of | expand |
diff --git a/fs/file.c b/fs/file.c index e8d2f9ef7fd1..a0e94a178c0b 100644 --- a/fs/file.c +++ b/fs/file.c @@ -268,7 +268,9 @@ 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 unsigned int count_open_files(struct fdtable *fdt)
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. Together with patch 1, they improves pts/blogbench-1.1.0 read for 28%, and write for 14% on Intel ICX 160 cores configuration with v6.8-rc6. Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by: Yu Ma <yu.ma@intel.com> --- fs/file.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)