diff options
| author | Andrew Morton <akpm@digeo.com> | 2003-05-07 08:19:50 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@home.transmeta.com> | 2003-05-07 08:19:50 -0700 |
| commit | 6a414e64bd6ffda2cbfe3505fcd67a66cf374cc9 (patch) | |
| tree | 588d6e251bcce2dc320d4543e1649147576c1a73 /include/linux/file.h | |
| parent | 09f9576108939bb7028f479b23b0314e7ae3a0cb (diff) | |
[PATCH] reduced overheads in fget/fput
From: Dipankar Sarma <dipankar@in.ibm.com>
fget() shows up on profiles, especially on SMP. Dipankar's patch
special-cases the situation wherein there are no sharers of current->files.
In this situation we know that no other process can close this file, so it
is not necessary to increment the file's refcount.
It's ugly as sin, but makes a substantial difference.
The test is
dd if=/dev/zero of=foo bs=1 count=1M
On 4CPU P3 xeon with 1MB L2 cache and 512MB ram:
kernel sys time std-dev
------------ -------- -------
UP - vanilla 2.104 0.028
UP - file 1.867 0.019
SMP - vanilla 2.976 0.023
SMP - file 2.719 0.026
Diffstat (limited to 'include/linux/file.h')
| -rw-r--r-- | include/linux/file.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/file.h b/include/linux/file.h index 6fbd27f755d5..a488f738f9f0 100644 --- a/include/linux/file.h +++ b/include/linux/file.h @@ -35,7 +35,15 @@ struct files_struct { extern void FASTCALL(__fput(struct file *)); extern void FASTCALL(fput(struct file *)); + +static inline void fput_light(struct file *file, int fput_needed) +{ + if (unlikely(fput_needed)) + fput(file); +} + extern struct file * FASTCALL(fget(unsigned int fd)); +extern struct file * FASTCALL(fget_light(unsigned int fd, int *fput_needed)); extern void FASTCALL(set_close_on_exec(unsigned int fd, int flag)); extern void put_filp(struct file *); extern int get_unused_fd(void); |