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| author | Alexey Dobriyan <adobriyan@gmail.com> | 2018-02-06 15:37:28 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-02-06 18:32:43 -0800 |
| commit | 15b158b4e6274351fc3cf652cbabc57104efb547 (patch) | |
| tree | b39beb6e526de60b5a89bd27c5419f7fbd7ead3d /fs/proc | |
| parent | efb1a57d90cae6af1ddd32f1b920c924a711aba5 (diff) | |
| download | linux-15b158b4e6274351fc3cf652cbabc57104efb547.tar.gz linux-15b158b4e6274351fc3cf652cbabc57104efb547.tar.bz2 linux-15b158b4e6274351fc3cf652cbabc57104efb547.zip | |
proc: spread likely/unlikely a bit
use_pde() is used at every open/read/write/... of every random /proc
file. Negative refcount happens only if PDE is being deleted by module
(read: never). So it gets "likely".
unuse_pde() gets "unlikely" for the same reason.
close_pdeo() gets unlikely as the completion is filled only if there is a
race between PDE removal and close() (read: never ever).
It even saves code on x86_64 defconfig:
add/remove: 0/0 grow/shrink: 1/2 up/down: 2/-20 (-18)
Function old new delta
close_pdeo 183 185 +2
proc_reg_get_unmapped_area 119 111 -8
proc_reg_poll 85 73 -12
Link: http://lkml.kernel.org/r/20180104175657.GA5204@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc')
| -rw-r--r-- | fs/proc/inode.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/proc/inode.c b/fs/proc/inode.c index c5c8e7af5520..6e8724958116 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -129,12 +129,12 @@ enum {BIAS = -1U<<31}; static inline int use_pde(struct proc_dir_entry *pde) { - return atomic_inc_unless_negative(&pde->in_use); + return likely(atomic_inc_unless_negative(&pde->in_use)); } static void unuse_pde(struct proc_dir_entry *pde) { - if (atomic_dec_return(&pde->in_use) == BIAS) + if (unlikely(atomic_dec_return(&pde->in_use) == BIAS)) complete(pde->pde_unload_completion); } @@ -167,7 +167,7 @@ static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) spin_lock(&pde->pde_unload_lock); /* After ->release. */ list_del(&pdeo->lh); - if (pdeo->c) + if (unlikely(pdeo->c)) complete(pdeo->c); kfree(pdeo); } @@ -421,7 +421,7 @@ static const char *proc_get_link(struct dentry *dentry, struct delayed_call *done) { struct proc_dir_entry *pde = PDE(inode); - if (unlikely(!use_pde(pde))) + if (!use_pde(pde)) return ERR_PTR(-EINVAL); set_delayed_call(done, proc_put_link, pde); return pde->data; |