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Commit 8c1fb49b authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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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: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d7a68be4

include/linux/tty.h

+2 −2
Original line number Diff line number Diff line
@@ -65,13 +65,13 @@ static inline char *flag_buf_ptr(struct tty_buffer *b, int ofs) 




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