diff options
| author | Mateusz Guzik <mjguzik@gmail.com> | 2025-03-17 00:24:21 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-03-18 15:34:27 +0100 |
| commit | 008a746a01e221b05932fd4561233ef35fa791cc (patch) | |
| tree | b6d9655f7792ed8d3d9c13edd87830ecee312f49 /fs/dcache.c | |
| parent | 514b68711164b557342bc6169d898576fa905c0f (diff) | |
fs: use wq_has_sleeper() in end_dir_add()
The routine is used a lot, while the wakeup almost never has anyone to
deal with.
wake_up_all() takes an irq-protected spinlock, wq_has_sleeper() "only"
contains a full fence -- not free by any means, but still cheaper.
Sample result tracing waiters using a custom probe during -j 20 kernel
build (0 - no waiters, 1 - waiters):
@[
wakeprobe+5
__wake_up_common+63
__wake_up+54
__d_add+234
d_splice_alias+146
ext4_lookup+439
path_openat+1746
do_filp_open+195
do_sys_openat2+153
__x64_sys_openat+86
do_syscall_64+82
entry_SYSCALL_64_after_hwframe+118
]:
[0, 1) 13999 |@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@|
[1, ...) 1 | |
Only 1 call out of 14000 with this backtrace had waiters.
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20250316232421.1642758-1-mjguzik@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/dcache.c')
| -rw-r--r-- | fs/dcache.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/fs/dcache.c b/fs/dcache.c index 9cc0d47da321..4d395b475ceb 100644 --- a/fs/dcache.c +++ b/fs/dcache.c @@ -2480,7 +2480,8 @@ static inline void end_dir_add(struct inode *dir, unsigned int n, { smp_store_release(&dir->i_dir_seq, n + 2); preempt_enable_nested(); - wake_up_all(d_wait); + if (wq_has_sleeper(d_wait)) + wake_up_all(d_wait); } static void d_wait_lookup(struct dentry *dentry) |