From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from vger.kernel.org (vger.kernel.org [23.128.96.18])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 0C7DAC67871
	for <linux-kernel@archiver.kernel.org>; Tue, 25 Oct 2022 02:52:10 +0000 (UTC)
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S231315AbiJYCvp (ORCPT <rfc822;linux-kernel@archiver.kernel.org>);
        Mon, 24 Oct 2022 22:51:45 -0400
Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40260 "EHLO
        lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S229800AbiJYCvk (ORCPT
        <rfc822;linux-kernel@vger.kernel.org>);
        Mon, 24 Oct 2022 22:51:40 -0400
Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1])
        by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 525E810CFA9
        for <linux-kernel@vger.kernel.org>; Mon, 24 Oct 2022 19:51:39 -0700 (PDT)
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
        (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
        (No client certificate requested)
        by dfw.source.kernel.org (Postfix) with ESMTPS id E25E761717
        for <linux-kernel@vger.kernel.org>; Tue, 25 Oct 2022 02:51:38 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C7D1C433C1;
        Tue, 25 Oct 2022 02:51:37 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;
        s=k20201202; t=1666666298;
        bh=7DyQiRYGX5iB56h+VCaUyEKZGSQILTTmtLWCE7ekI1Y=;
        h=Date:Subject:To:Cc:References:From:In-Reply-To:From;
        b=O66ZC1UOs3IINrIKW1K/NMPMYa3qZ77OXjOYdQD1MJafjJTQqu2mkAzzpHlC3Qu0H
         aFxedUBT4fcW71hIHgNm0oGKhg7cDLfRTHlmjFhFox1G2FlmcW3zLQYObATzKbOSKR
         SsazqazQPPhjdkaCOqI33FBI/QBeO11GS0xqYE9tXbu39Osud66VVdrD0R1UNhaEJ4
         iRdSR2SCSMX5i2jityCRBRrl3EmEGm8wAVNNjt16mOppuM7/jpEUTGRWmcFC+hn9RZ
         cs/xkbNbY7qWcpOzIK42zzwZAfEHT2tJ9FJdAMxKwoc2rqx+3ld0ew2cle8flSfoVe
         I+NI0Cqcwl5Fw==
Message-ID: <429625d3-ca81-d067-deb7-e9d40725eaf0@kernel.org>
Date:   Tue, 25 Oct 2022 10:51:33 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.3.1
Subject: Re: [f2fs-dev] [PATCH] f2fs: make gc_idle sysfs node readable
Content-Language: en-US
To:     Yangtao Li <frank.li@vivo.com>, jaegeuk@kernel.org
Cc:     linux-f2fs-devel@lists.sourceforge.net,
        linux-kernel@vger.kernel.org
References: <dfc051bb-71ca-035c-b945-ad298aa5e1ae@kernel.org>
 <20221025023334.77096-1-frank.li@vivo.com>
From:   Chao Yu <chao@kernel.org>
In-Reply-To: <20221025023334.77096-1-frank.li@vivo.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2022/10/25 10:33, Yangtao Li wrote:
> Hi Chao,
> 
> What:       /sys/fs/f2fs/<disk>/gc_idle
> Date:       July 2013
> Contact:    "Namjae Jeon" <namjae.jeon@samsung.com>
> Description:    Controls the victim selection policy for garbage collection.
>          Setting gc_idle = 0(default) will disable this option. Setting:
> 
>          ===========  ===============================================
>          gc_idle = 1  will select the Cost Benefit approach & setting
>          gc_idle = 2  will select the greedy approach & setting
>          gc_idle = 3  will select the age-threshold based approach.
>          ===========  ===============================================
> 
>  From the kernel documentation, this node only describes the writing of
> the value, and does not describe the reading of the value.

  If the value is used by userspace program, after the change, it will break
userspace.

> 
> Actually, this modification does the same thing as commit e60aeb2dee1a
> ("f2fs: make gc_urgent and gc_segment_mode sysfs node readabl").
> I understand it is an addition to the omission of the patch above.
> 
> Why gc_urgent and gc_segment_mode can be modified to string, but gc_idle
> breaks forward compatibility?

Oops, I guess that patch may have caused a regression...if there is any
user..

> 
> Thanks,

From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-f2fs-devel-bounces@lists.sourceforge.net>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
Received: from lists.sourceforge.net (lists.sourceforge.net [216.105.38.7])
	(using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
	(No client certificate requested)
	by smtp.lore.kernel.org (Postfix) with ESMTPS id 98205FA373D
	for <linux-f2fs-devel@archiver.kernel.org>; Tue, 25 Oct 2022 02:51:56 +0000 (UTC)
Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com)
	by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.95)
	(envelope-from <linux-f2fs-devel-bounces@lists.sourceforge.net>)
	id 1onA2l-0002nK-RL;
	Tue, 25 Oct 2022 02:51:55 +0000
Received: from [172.30.20.202] (helo=mx.sourceforge.net)
 by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls
 TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95)
 (envelope-from <chao@kernel.org>) id 1onA2k-0002nD-3C
 for linux-f2fs-devel@lists.sourceforge.net;
 Tue, 25 Oct 2022 02:51:54 +0000
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed;
 d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:In-Reply-To:
 From:References:Cc:To:Subject:MIME-Version:Date:Message-ID:Sender:Reply-To:
 Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender:
 Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:
 List-Subscribe:List-Post:List-Owner:List-Archive;
 bh=f8K7aGlVrTIkSNksNXEF0TAoOdjxtG6XGtVJh9hMb9U=; b=F2fK7Sl3iRk1b4286SxmM2bSHN
 ljsObeoAyArbuk9boXoM92YRsUpceb9VuKulKWAQ0NV3zfugsXBcnyGUPkNjApN3C2rSona9dlJ9k
 hR5vfXKV8ENOYa6/g9SZ5F/k/H9HmOzwJgf2+ClTZR1nFhZlmxtSj7bfYi4rzqCsAWy8=;
DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x
 ;
 h=Content-Transfer-Encoding:Content-Type:In-Reply-To:From:References:Cc:To:
 Subject:MIME-Version:Date:Message-ID:Sender:Reply-To:Content-ID:
 Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc
 :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe:
 List-Post:List-Owner:List-Archive;
 bh=f8K7aGlVrTIkSNksNXEF0TAoOdjxtG6XGtVJh9hMb9U=; b=DM91jqpTXXcXRV/7wvCyEXxPbP
 XhQLw4/UhQYJ4g6FfbJ3KgpVrfX9K2firA6GfNXAniktwBc+A/5Y4WxKnKtasCuAx0AYImv7LrbV/
 XJRv5uWjvlUzfiypz7LnXRQdziH8yn3fze1B2Rkuk99T6uVJcMmRsBSil1rXdYdE/lag=;
Received: from dfw.source.kernel.org ([139.178.84.217])
 by sfi-mx-2.v28.lw.sourceforge.com with esmtps
 (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95)
 id 1onA2f-0000MH-Ql for linux-f2fs-devel@lists.sourceforge.net;
 Tue, 25 Oct 2022 02:51:54 +0000
Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (No client certificate requested)
 by dfw.source.kernel.org (Postfix) with ESMTPS id DEBF7616FE;
 Tue, 25 Oct 2022 02:51:38 +0000 (UTC)
Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3C7D1C433C1;
 Tue, 25 Oct 2022 02:51:37 +0000 (UTC)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org;
 s=k20201202; t=1666666298;
 bh=7DyQiRYGX5iB56h+VCaUyEKZGSQILTTmtLWCE7ekI1Y=;
 h=Date:Subject:To:Cc:References:From:In-Reply-To:From;
 b=O66ZC1UOs3IINrIKW1K/NMPMYa3qZ77OXjOYdQD1MJafjJTQqu2mkAzzpHlC3Qu0H
 aFxedUBT4fcW71hIHgNm0oGKhg7cDLfRTHlmjFhFox1G2FlmcW3zLQYObATzKbOSKR
 SsazqazQPPhjdkaCOqI33FBI/QBeO11GS0xqYE9tXbu39Osud66VVdrD0R1UNhaEJ4
 iRdSR2SCSMX5i2jityCRBRrl3EmEGm8wAVNNjt16mOppuM7/jpEUTGRWmcFC+hn9RZ
 cs/xkbNbY7qWcpOzIK42zzwZAfEHT2tJ9FJdAMxKwoc2rqx+3ld0ew2cle8flSfoVe
 I+NI0Cqcwl5Fw==
Message-ID: <429625d3-ca81-d067-deb7-e9d40725eaf0@kernel.org>
Date: Tue, 25 Oct 2022 10:51:33 +0800
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101
 Thunderbird/102.3.1
Content-Language: en-US
To: Yangtao Li <frank.li@vivo.com>, jaegeuk@kernel.org
References: <dfc051bb-71ca-035c-b945-ad298aa5e1ae@kernel.org>
 <20221025023334.77096-1-frank.li@vivo.com>
From: Chao Yu <chao@kernel.org>
In-Reply-To: <20221025023334.77096-1-frank.li@vivo.com>
X-Headers-End: 1onA2f-0000MH-Ql
Subject: Re: [f2fs-dev] [PATCH] f2fs: make gc_idle sysfs node readable
X-BeenThere: linux-f2fs-devel@lists.sourceforge.net
X-Mailman-Version: 2.1.21
Precedence: list
List-Id: <linux-f2fs-devel.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/options/linux-f2fs-devel>, 
 <mailto:linux-f2fs-devel-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=linux-f2fs-devel>
List-Post: <mailto:linux-f2fs-devel@lists.sourceforge.net>
List-Help: <mailto:linux-f2fs-devel-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel>, 
 <mailto:linux-f2fs-devel-request@lists.sourceforge.net?subject=subscribe>
Cc: linux-kernel@vger.kernel.org, linux-f2fs-devel@lists.sourceforge.net
Content-Transfer-Encoding: 7bit
Content-Type: text/plain; charset="us-ascii"; Format="flowed"
Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net

On 2022/10/25 10:33, Yangtao Li wrote:
> Hi Chao,
> 
> What:       /sys/fs/f2fs/<disk>/gc_idle
> Date:       July 2013
> Contact:    "Namjae Jeon" <namjae.jeon@samsung.com>
> Description:    Controls the victim selection policy for garbage collection.
>          Setting gc_idle = 0(default) will disable this option. Setting:
> 
>          ===========  ===============================================
>          gc_idle = 1  will select the Cost Benefit approach & setting
>          gc_idle = 2  will select the greedy approach & setting
>          gc_idle = 3  will select the age-threshold based approach.
>          ===========  ===============================================
> 
>  From the kernel documentation, this node only describes the writing of
> the value, and does not describe the reading of the value.

  If the value is used by userspace program, after the change, it will break
userspace.

> 
> Actually, this modification does the same thing as commit e60aeb2dee1a
> ("f2fs: make gc_urgent and gc_segment_mode sysfs node readabl").
> I understand it is an addition to the omission of the patch above.
> 
> Why gc_urgent and gc_segment_mode can be modified to string, but gc_idle
> breaks forward compatibility?

Oops, I guess that patch may have caused a regression...if there is any
user..

> 
> Thanks,


_______________________________________________
Linux-f2fs-devel mailing list
Linux-f2fs-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel