From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7955FC43467 for ; Fri, 16 Oct 2020 14:22:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 27E4920848 for ; Fri, 16 Oct 2020 14:22:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2408795AbgJPOWR (ORCPT ); Fri, 16 Oct 2020 10:22:17 -0400 Received: from mx2.suse.de ([195.135.220.15]:44708 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394682AbgJPOWR (ORCPT ); Fri, 16 Oct 2020 10:22:17 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id CB938B1F7; Fri, 16 Oct 2020 14:22:15 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id C5986DA7C3; Fri, 16 Oct 2020 16:20:47 +0200 (CEST) Date: Fri, 16 Oct 2020 16:20:47 +0200 From: David Sterba To: Nikolay Borisov Cc: linux-btrfs@vger.kernel.org Subject: Re: [PATCH 4/4] btrfs: Be smarter when sleeping in transaction_kthread Message-ID: <20201016142047.GS6756@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Nikolay Borisov , linux-btrfs@vger.kernel.org References: <20201008122430.93433-1-nborisov@suse.com> <20201008122430.93433-5-nborisov@suse.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201008122430.93433-5-nborisov@suse.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Oct 08, 2020 at 03:24:30PM +0300, Nikolay Borisov wrote: > If transaction_kthread is woken up before > btrfs_fs_info::commit_interval seconds have elapsed it will sleep for a > fixed period of 5 seconds. This is not a problem per-se but is not > accuaret, instead the code should sleep for an interval which guarantees > on next wakeup commit_interval would have passed. Since time tracking is > not accurate add 1 second to ensure next wake up would be after > commit_interval. > > Signed-off-by: Nikolay Borisov > --- > fs/btrfs/disk-io.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c > index c5d3e7f75066..a1fe99cf0831 100644 > --- a/fs/btrfs/disk-io.c > +++ b/fs/btrfs/disk-io.c > @@ -1735,7 +1735,7 @@ static int transaction_kthread(void *arg) > if (cur->state < TRANS_STATE_COMMIT_START && > delta < fs_info->commit_interval) { > spin_unlock(&fs_info->trans_lock); > - delay = msecs_to_jiffies(5000); > + delay = msecs_to_jiffies((1+delta) * 1000); This does not seem right. Delta is number of seconds since the transaction started, so we need to sleep for the remaining time. Which is commit_interval - delta.