tty: Avoid false-sharing flip buffer ptrs
Separate the head and tail ptrs 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>
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 1d5bacc..b8e8adf 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -65,13 +65,13 @@
struct tty_bufhead {
+ struct tty_buffer *head; /* Queue head */
struct work_struct work;
struct mutex flush_mutex;
struct tty_buffer sentinel;
- struct tty_buffer *head; /* Queue head */
- struct tty_buffer *tail; /* Active buffer */
struct llist_head free; /* Free queue head */
atomic_t memory_used; /* In-use buffers excluding free list */
+ struct tty_buffer *tail; /* Active buffer */
};
/*
* When a break, frame error, or parity error happens, these codes are