From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755330Ab2JIMjo (ORCPT ); Tue, 9 Oct 2012 08:39:44 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56492 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752786Ab2JIMjm (ORCPT ); Tue, 9 Oct 2012 08:39:42 -0400 Date: Tue, 9 Oct 2012 14:39:06 +0200 (CEST) From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= X-X-Sender: lukas@dhcp-1-104.brq.redhat.com To: Jaegeuk Kim cc: "=?ISO-8859-15?Q?'Luk=E1=A8_Czerner'?=" , "'Namjae Jeon'" , "'Vyacheslav Dubeyko'" , "'Marco Stornelli'" , "'Jaegeuk Kim'" , "'Al Viro'" , tytso@mit.edu, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, chur.lee@samsung.com, cm224.lee@samsung.com, jooyoung.hwang@samsung.com, linux-fsdevel@vger.kernel.org Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system In-Reply-To: <008301cda615$ca3b9980$5eb2cc80$%kim@samsung.com> Message-ID: References: <415E76CC-A53D-4643-88AB-3D7D7DC56F98@dubeyko.com> <9DE65D03-D4EA-4B32-9C1D-1516EAE50E23@dubeyko.com> <1349553966.12699.132.camel@kjgkr> <50712AAA.5030807@gmail.com> <002201cda46e$88b84d30$9a28e790$%kim@samsung.com> <004101cda52e$72210e20$56632a60$%kim@samsung.com> <004a01cda542$f398e2c0$dacaa840$%kim@samsung.com> <007c01cda60b$43e7fae0$cbb7f0a0$%kim@samsung.com> <008301cda615$ca3b9980$5eb2cc80$%kim@samsung.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 9 Oct 2012, Jaegeuk Kim wrote: > > > > > > > > > > > > > > As you can see the f2fs kernel document patch, I think one of the most > > > > > > > important features is to align operating units between f2fs and ftl. > > > > > > > Specifically, f2fs has section and zone, which are cleaning unit and basic > > > > > > > allocation unit respectively. > > > > > > > Through these configurable units in f2fs, I think f2fs is able to reduce the > > > > > > > unnecessary operations done by FTL. > > > > > > > And, in order to avoid changing IO patterns by the block-layer, f2fs merges > > > > > > > itself some bios likewise ext4. > > > > > > Hello. > > > > > > The internal of eMMC and SSD is the blackbox from user side. > > > > > > How does the normal user easily set operating units alignment(page > > > > > > size and physical block size ?) between f2fs and ftl in storage device > > > > > > ? > > > > > > > > > > I've known that some works have been tried to figure out the units by profiling the storage, AKA > > > > reverse engineering. > > > > > In most cases, the simplest way is to measure the latencies of consecutive writes and analyze > > their > > > > patterns. > > > > > As you mentioned, in practical, users will not want to do this, so maybe we need a tool to > > profile > > > > them to optimize f2fs. > > > > > In the current state, I think profiling is an another issue, and mkfs.f2fs had better include > > this > > > > work in the future. > > > > > But, IMO, from the viewpoint of performance, default configuration is quite enough now. > > > > > > > > > > ps) f2fs doesn't care about the flash page size, but considers garbage collection unit. > > > > > > > > I am sorry but this reply makes me smile. How can you design a fs > > > > relying on time attack heuristics to figure out what the proper > > > > layout should be ? Or even endorse such heuristics to be used in > > > > mkfs ? What we should be focusing on is to push vendors to actually > > > > give us such information so we can properly propagate that > > > > throughout the kernel - that's something everyone will benefit from. > > > > After that the optimization can be done in every file system. > > > > > > > > > > Frankly speaking, I agree that it would be the right direction eventually. > > > But, as you know, it's very difficult for all flash vendors to promote and standardize that. > > > Because each vendors have different strategies to open their internal information and also try > > > to protect their secrets whatever they are. > > > > > > IMO, we don't need to wait them now. > > > Instead, from the start, I suggest f2fs that uses those information to the file system design. > > > In addition, I suggest using heuristics right now as best efforts. > > > Maybe in future, if vendors give something, f2fs would be more feasible. > > > In the mean time, I strongly hope to validate and stabilize f2fs with community. > > > > Do not get me wrong, I do not think it is worth to wait for vendors > > to come to their senses, but it is worth constantly reminding that > > we *need* this kind of information and those heuristics are not > > feasible in the long run anyway. > > > > I believe that this conversation happened several times already, but > > what about having independent public database of all the internal > > information about hw from different vendors where users can add > > information gathered by the time attack heuristic so other does not > > have to run this again and again. I am not sure if Linaro or someone > > else have something like that, someone can maybe post a link to that. > > > > As I mentioned, I agree to push vendors to open those information all the time. > And, I absolutely didn't mean that it is worth to wait vendors. > I meant, until opening those information by vendors, something like > proposing f2fs or gathering heuristics are also needed simultaneously. > > Anyway, it's very interesting to build a database gathering products' information. > May I access the database? That's what I found: https://wiki.linaro.org/WorkingGroups/Kernel/Projects/FlashCardSurvey -Lukas > > Thanks, > > > Eventually we can show this to the vendors to see that their > > "secrets" are already public anyway and that everyones lives would be > > easier if they just agree to provide it from the beginning. > > > > > > > > > Promoting time attack heuristics instead of pushing vendors to tell > > > > us how their hardware should be used is a journey to hell and we've > > > > been talking about this for a looong time now. And I imagine that > > > > you especially have quite some persuasion power. > > > > > > I know. :) > > > If there comes a chance, I want to try. > > > Thanks, > > > > That's very good to hear, thank you. > > > > -Lukas