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@xxxxxxxxxxxxxxxxxx>
---
drivers/tty/n_tty.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c
index eb20777..aa63cd3 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;
--
1.8.1.2
--
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