From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753430Ab2H0QCT (ORCPT ); Mon, 27 Aug 2012 12:02:19 -0400 Received: from mail-pz0-f46.google.com ([209.85.210.46]:45940 "EHLO mail-pz0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753377Ab2H0QBw (ORCPT ); Mon, 27 Aug 2012 12:01:52 -0400 From: Namjae Jeon To: fengguang.wu@intel.com, akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, Namjae Jeon , Namjae Jeon , Vivek Trivedi Subject: [PATCH 2/2] Documentation: add description of dirty_background_time Date: Mon, 27 Aug 2012 12:01:41 -0400 Message-Id: <1346083301-3545-1-git-send-email-linkinjeon@gmail.com> X-Mailer: git-send-email 1.7.9.5 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Namjae Jeon This commit adds dirty_background_time description in bdi sysfs documentation. Signed-off-by: Namjae Jeon Signed-off-by: Vivek Trivedi --- Documentation/ABI/testing/sysfs-class-bdi | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index 5f50097..018e26a 100644 --- a/Documentation/ABI/testing/sysfs-class-bdi +++ b/Documentation/ABI/testing/sysfs-class-bdi @@ -48,3 +48,16 @@ max_ratio (read-write) most of the write-back cache. For example in case of an NFS mount that is prone to get stuck, or a FUSE mount which cannot be trusted to play fair. + +dirty_background_time (read-write) + + It is used to start early writeback of given bdi once bdi dirty + data exceeds product of average write bandwidth and + dirty_background_time. It is mainly useful for tuning writeback + speed at 'NFS Server' so that NFS client could see better write speed. + + However, sometimes it may not match user expectations as it is based + on bdi write bandwidth estimation. Write bandwidth estimation is a + best effort to estimate bdi write speed bandwidth. But it can be + wildly wrong in certain situations. + dirty_background_time is expressed in msec. -- 1.7.9.5