From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753375AbdJNAw1 (ORCPT ); Fri, 13 Oct 2017 20:52:27 -0400 Received: from mail-pf0-f196.google.com ([209.85.192.196]:50011 "EHLO mail-pf0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752966AbdJNAw0 (ORCPT ); Fri, 13 Oct 2017 20:52:26 -0400 X-Google-Smtp-Source: AOwi7QAlwkM9kGxMHzrbQWwYPM6zBZmZjBBsuBEr0t2oFZwPVoAylHt4abUindc6fRtcwMduwDeQoQ== From: Yafang Shao To: axboe@kernel.dk, akpm@linux-foundation.org Cc: jack@suse.cz, hannes@cmpxchg.org, vdavydov.dev@gmail.com, jlayton@redhat.com, nborisov@suse.com, tytso@mit.edu, yamada.masahiro@socionext.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, laoar.shao@gmail.com Subject: [PATCH for linux-next] mm/page-writeback.c: make changes of dirty_writeback_centisecs take effect immediately Date: Sat, 14 Oct 2017 16:38:27 +0800 Message-Id: <1507970307-16431-1-git-send-email-laoar.shao@gmail.com> X-Mailer: git-send-email 1.8.3.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch is the followup of the prvious patch: [writeback: schedule periodic writeback with sysctl]. There's another issue to fix. For example, - When the tunable was set to one hour and is reset to one second, the new setting will not take effect for up to one hour. Kicking the flusher threads immediately fixes it. Cc: Jens Axboe Cc: Jan Kara Cc: Andrew Morton Signed-off-by: Yafang Shao --- mm/page-writeback.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/mm/page-writeback.c b/mm/page-writeback.c index 3969e69..768fe4e 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -1978,7 +1978,16 @@ int dirty_writeback_centisecs_handler(struct ctl_table *table, int write, int ret; ret = proc_dointvec(table, write, buffer, length, ppos); - if (!ret && !old_interval && dirty_writeback_interval) + + /* + * Writing 0 to dirty_writeback_interval will disable periodic writeback + * and a different non-zero value will wakeup the writeback threads. + * wb_wakeup_delayed() would be more appropriate, but it's a pain to + * iterate over all bdis and wbs. + * The reason we do this is to make the change take effect immediately. + */ + if (!ret && write && dirty_writeback_interval && + dirty_writeback_interval != old_interval) wakeup_flusher_threads(WB_REASON_PERIODIC); return ret; -- 1.8.3.1