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| author | Oleg Nesterov <oleg@redhat.com> | 2025-02-05 19:18:12 +0100 |
|---|---|---|
| committer | Christian Brauner <brauner@kernel.org> | 2025-02-06 10:50:55 +0100 |
| commit | f017b0a4951fac8f150232661b2cc0b67e0c57f0 (patch) | |
| tree | 341f1c778a59a9831b02614d6075ce16d85656c7 /fs/pipe.c | |
| parent | 262b2fa99cbe02a715ce23981c2c30685ccf3a93 (diff) | |
| download | random-f017b0a4951fac8f150232661b2cc0b67e0c57f0.tar.gz | |
pipe: don't update {a,c,m}time for anonymous pipes
These numbers are visible in fstat() but hopefully nobody uses this
information and file_accessed/file_update_time are not that cheap.
Stupid test-case:
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <assert.h>
#include <sys/ioctl.h>
#include <sys/time.h>
static char buf[17 * 4096];
static struct timeval TW, TR;
int wr(int fd, int size)
{
int c, r;
struct timeval t0, t1;
gettimeofday(&t0, NULL);
for (c = 0; (r = write(fd, buf, size)) > 0; c += r);
gettimeofday(&t1, NULL);
timeradd(&TW, &t1, &TW);
timersub(&TW, &t0, &TW);
return c;
}
int rd(int fd, int size)
{
int c, r;
struct timeval t0, t1;
gettimeofday(&t0, NULL);
for (c = 0; (r = read(fd, buf, size)) > 0; c += r);
gettimeofday(&t1, NULL);
timeradd(&TR, &t1, &TR);
timersub(&TR, &t0, &TR);
return c;
}
int main(int argc, const char *argv[])
{
int fd[2], nb = 1, loop, size;
assert(argc == 3);
loop = atoi(argv[1]);
size = atoi(argv[2]);
assert(pipe(fd) == 0);
assert(ioctl(fd[0], FIONBIO, &nb) == 0);
assert(ioctl(fd[1], FIONBIO, &nb) == 0);
assert(size <= sizeof(buf));
while (loop--)
assert(wr(fd[1], size) == rd(fd[0], size));
struct timeval tt;
timeradd(&TW, &TR, &tt);
printf("TW = %lu.%03lu TR = %lu.%03lu TT = %lu.%03lu\n",
TW.tv_sec, TW.tv_usec/1000,
TR.tv_sec, TR.tv_usec/1000,
tt.tv_sec, tt.tv_usec/1000);
return 0;
}
Before:
# for i in 1 2 3; do /host/tmp/test 10000 100; done
TW = 8.047 TR = 5.845 TT = 13.893
TW = 8.091 TR = 5.872 TT = 13.963
TW = 8.083 TR = 5.885 TT = 13.969
After:
# for i in 1 2 3; do /host/tmp/test 10000 100; done
TW = 4.752 TR = 4.664 TT = 9.416
TW = 4.684 TR = 4.608 TT = 9.293
TW = 4.736 TR = 4.652 TT = 9.388
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lore.kernel.org/r/20250205181812.GC13817@redhat.com
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Diffstat (limited to 'fs/pipe.c')
| -rw-r--r-- | fs/pipe.c | 41 |
1 files changed, 29 insertions, 12 deletions
diff --git a/fs/pipe.c b/fs/pipe.c index 2eacfde61e745f..2ae75adfba64bd 100644 --- a/fs/pipe.c +++ b/fs/pipe.c @@ -248,7 +248,7 @@ static inline unsigned int pipe_update_tail(struct pipe_inode_info *pipe, } static ssize_t -pipe_read(struct kiocb *iocb, struct iov_iter *to) +anon_pipe_read(struct kiocb *iocb, struct iov_iter *to) { size_t total_len = iov_iter_count(to); struct file *filp = iocb->ki_filp; @@ -404,8 +404,15 @@ pipe_read(struct kiocb *iocb, struct iov_iter *to) if (wake_next_reader) wake_up_interruptible_sync_poll(&pipe->rd_wait, EPOLLIN | EPOLLRDNORM); kill_fasync(&pipe->fasync_writers, SIGIO, POLL_OUT); + return ret; +} + +static ssize_t +fifo_pipe_read(struct kiocb *iocb, struct iov_iter *to) +{ + int ret = anon_pipe_read(iocb, to); if (ret > 0) - file_accessed(filp); + file_accessed(iocb->ki_filp); return ret; } @@ -426,7 +433,7 @@ static inline bool pipe_writable(const struct pipe_inode_info *pipe) } static ssize_t -pipe_write(struct kiocb *iocb, struct iov_iter *from) +anon_pipe_write(struct kiocb *iocb, struct iov_iter *from) { struct file *filp = iocb->ki_filp; struct pipe_inode_info *pipe = filp->private_data; @@ -604,11 +611,21 @@ out: kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN); if (wake_next_writer) wake_up_interruptible_sync_poll(&pipe->wr_wait, EPOLLOUT | EPOLLWRNORM); - if (ret > 0 && sb_start_write_trylock(file_inode(filp)->i_sb)) { - int err = file_update_time(filp); - if (err) - ret = err; - sb_end_write(file_inode(filp)->i_sb); + return ret; +} + +static ssize_t +fifo_pipe_write(struct kiocb *iocb, struct iov_iter *from) +{ + int ret = anon_pipe_write(iocb, from); + if (ret > 0) { + struct file *filp = iocb->ki_filp; + if (sb_start_write_trylock(file_inode(filp)->i_sb)) { + int err = file_update_time(filp); + if (err) + ret = err; + sb_end_write(file_inode(filp)->i_sb); + } } return ret; } @@ -1234,8 +1251,8 @@ err: const struct file_operations pipefifo_fops = { .open = fifo_open, - .read_iter = pipe_read, - .write_iter = pipe_write, + .read_iter = fifo_pipe_read, + .write_iter = fifo_pipe_write, .poll = pipe_poll, .unlocked_ioctl = pipe_ioctl, .release = pipe_release, @@ -1245,8 +1262,8 @@ const struct file_operations pipefifo_fops = { static const struct file_operations pipeanon_fops = { .open = fifo_open, - .read_iter = pipe_read, - .write_iter = pipe_write, + .read_iter = anon_pipe_read, + .write_iter = anon_pipe_write, .poll = pipe_poll, .unlocked_ioctl = pipe_ioctl, .release = pipe_release, |