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| author | Peter Hurley | 2013-06-15 16:04:29 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman | 2013-07-24 02:02:22 +0200 |
| commit | 9dfd16ddea9bdbc8343340e543732db0a467ae32 (patch) | |
| tree | f5ab13fd7bbc7ff99ccc44ecf127fede65452dc2 /drivers/tty/n_tty.c | |
| parent | n_tty: Eliminate counter in __process_echoes (diff) | |
| download | kernel-qcow2-linux-9dfd16ddea9bdbc8343340e543732db0a467ae32.tar.gz kernel-qcow2-linux-9dfd16ddea9bdbc8343340e543732db0a467ae32.tar.xz kernel-qcow2-linux-9dfd16ddea9bdbc8343340e543732db0a467ae32.zip | |
n_tty: Avoid false-sharing echo buffer indices
Separate the head & commit indices from the tail index to avoid
cache-line contention (so called 'false-sharing') between concurrent
threads.
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty/n_tty.c')
| -rw-r--r-- | drivers/tty/n_tty.c | 9 |
1 files changed, 4 insertions, 5 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 7f15b269cf3e..d4d71350a71d 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -90,6 +90,8 @@ struct n_tty_data { /* producer-published */ size_t read_head; size_t canon_head; + size_t echo_head; + size_t echo_commit; DECLARE_BITMAP(process_char_map, 256); /* private to n_tty_receive_overrun (single-threaded) */ @@ -105,20 +107,17 @@ struct n_tty_data { /* shared by producer and consumer */ char *read_buf; DECLARE_BITMAP(read_flags, N_TTY_BUF_SIZE); + unsigned char *echo_buf; int minimum_to_wake; /* consumer-published */ size_t read_tail; - unsigned char *echo_buf; - size_t echo_head; - size_t echo_tail; - size_t echo_commit; - /* protected by output lock */ unsigned int column; unsigned int canon_column; + size_t echo_tail; struct mutex atomic_read_lock; struct mutex output_lock; |