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=-1.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_PASS 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 94F48C433F5 for ; Sun, 2 Sep 2018 08:53:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3B6B220855 for ; Sun, 2 Sep 2018 08:53:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="hRI3abis" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 3B6B220855 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726961AbeIBNH7 (ORCPT ); Sun, 2 Sep 2018 09:07:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:58258 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725834AbeIBNH7 (ORCPT ); Sun, 2 Sep 2018 09:07:59 -0400 Received: from [192.168.0.101] (unknown [49.77.178.191]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 831D92077C; Sun, 2 Sep 2018 08:52:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1535878378; bh=ORYRmp7XvZNceMFVVyDNeNUqZnpIo8F+RNdd/HHbGtg=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=hRI3abisOJuALg3Cr3eJNCMvX6GTr9IMk+vYGbuVQ3sStctjSmx/kn+KFtDzBeb1u r4XNaEmyPm6YfbFwBDvVAzb28lgJ2Ipkz6HiMi7KiX4ncg3kgx/Elg7dnN61Iak2wO mowf3K6v1k19rn6Ho2Ofz29rhqd/QbkTx0Xxy0qI= Subject: Re: [f2fs-dev] [PATCH] f2fs: fix unnecessary periodic wakeup of discard thread when dev is busy To: Sahitya Tummala , Jaegeuk Kim , Chao Yu , linux-f2fs-devel@lists.sourceforge.net Cc: linux-kernel@vger.kernel.org References: <1535708366-11318-1-git-send-email-stummala@codeaurora.org> From: Chao Yu Message-ID: Date: Sun, 2 Sep 2018 16:52:40 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1535708366-11318-1-git-send-email-stummala@codeaurora.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2018/8/31 17:39, Sahitya Tummala wrote: > When dev is busy, discard thread wake up timeout can be aligned with the > exact time that it needs to wait for dev to come out of busy. This helps > to avoid unnecessary periodic wakeups and thus save some power. > > Signed-off-by: Sahitya Tummala > --- > fs/f2fs/segment.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c > index 8bcbb50..df14030 100644 > --- a/fs/f2fs/segment.c > +++ b/fs/f2fs/segment.c > @@ -1379,6 +1379,8 @@ static int issue_discard_thread(void *data) > struct discard_policy dpolicy; > unsigned int wait_ms = DEF_MIN_DISCARD_ISSUE_TIME; > int issued; > + unsigned long interval = sbi->interval_time[REQ_TIME] * HZ; > + long delta; > > set_freezable(); > > @@ -1410,7 +1412,11 @@ static int issue_discard_thread(void *data) > __wait_all_discard_cmd(sbi, &dpolicy); > wait_ms = dpolicy.min_interval; > } else if (issued == -1){ > - wait_ms = dpolicy.mid_interval; > + delta = (sbi->last_time[REQ_TIME] + interval) - jiffies; I agree that we need to consider power consumption. One more consideration is that discard thread may need different submission frequency comparing to garbage collection thread, maybe a little fast, would it be better to split sbi->interval_time[REQ_TIME] according to gc/discard type. How do you think? Thanks, > + if (delta > 0) > + wait_ms = jiffies_to_msecs(delta); > + else > + wait_ms = dpolicy.mid_interval; > } else { > wait_ms = dpolicy.max_interval; > } >