From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754615Ab3FON6i (ORCPT ); Sat, 15 Jun 2013 09:58:38 -0400 Received: from mailout01.c08.mtsvc.net ([205.186.168.189]:40064 "EHLO mailout01.c08.mtsvc.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754462Ab3FON54 (ORCPT ); Sat, 15 Jun 2013 09:57:56 -0400 From: Peter Hurley To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Jiri Slaby , Peter Hurley Subject: [PATCH v2 12/16] tty: Avoid false-sharing flip buffer ptrs Date: Sat, 15 Jun 2013 09:36:12 -0400 Message-Id: <1371303376-5028-13-git-send-email-peter@hurleysoftware.com> X-Mailer: git-send-email 1.8.1.2 In-Reply-To: <1371303376-5028-1-git-send-email-peter@hurleysoftware.com> References: <1371302076-4688-1-git-send-email-peter@hurleysoftware.com> <1371303376-5028-1-git-send-email-peter@hurleysoftware.com> X-Authenticated-User: 125194 peter@hurleysoftware.com Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Separate the head and tail ptrs to avoid cache-line contention (so called 'false-sharing') between concurrent threads. Signed-off-by: Peter Hurley --- include/linux/tty.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) 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 @@ 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 -- 1.8.1.2