Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754014Ab2JIIBA (ORCPT ); Tue, 9 Oct 2012 04:01:00 -0400 Received: from mailout4.samsung.com ([203.254.224.34]:48043 "EHLO mailout4.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753884Ab2JIIA4 convert rfc822-to-8bit (ORCPT ); Tue, 9 Oct 2012 04:00:56 -0400 X-AuditID: cbfee61b-b7f2b6d000000f14-55-5073d9b7fe8e From: Jaegeuk Kim To: "'Namjae Jeon'" Cc: "'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 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> <004c01cda54e$15cd4a60$4167df20$%kim@samsung.com> In-reply-to: Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system Date: Tue, 09 Oct 2012 17:00:54 +0900 Message-id: <007001cda5f4$353c4d00$9fb4e700$%kim@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-transfer-encoding: 8BIT X-Mailer: Microsoft Office Outlook 12.0 Thread-index: Ac2l0XhhLDnhWOsrRL296iAeVEjR5gAIppHA Content-language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrELMWRmVeSWpSXmKPExsVy+t9jAd3tN4sDDDbf47DYs/cki8XlXXPY HJg8Pm+SC2CM4rJJSc3JLEst0rdL4MqYvXISU8H+bsaKFb3LWRoYb2d2MXJySAiYSGyY/oEd whaTuHBvPVsXIxeHkMAiRonDk+azQzj/GCVmnDkL5HBwsAloS2zebwDSICKgIfFg+1awGmaB R0wSn/r/MUM09LNKdDduZAWp4hQIlnjQtZMJxBYWcJVo/9POCGKzCKhK/L/zlQ3E5hWwlVhy 7SgjhC0o8WPyPRaQZcwC6hJTpuSChJmB9j55d4EVJCwBFH70VxfiBiOJ70va2SFKRCT2vXjH OIFRaBaSQbMQBs1CMmgWko4FjCyrGEVTC5ILipPSc430ihNzi0vz0vWS83M3MYJD+pn0DsZV DRaHGAU4GJV4eD9EFQcIsSaWFVfmHmKU4GBWEuG9nggU4k1JrKxKLcqPLyrNSS0+xCjNwaIk ztvskRIgJJCeWJKanZpakFoEk2Xi4JRqYAzb27F/9YTSKyd4tTdlf462da89+zy3Ztvmyn/Z /RuDA65GVZYXca2//3/VMlfuILWJn3+LHP/NoO0qZFPULPu0jMlEQ31Favafr9k5i+fmVvcF LG21a5i25o/Jx6nyt79nMoRPTevdsPFcVGwszwr1OvYdgidCt7FP4k6TX5YqEmL03cTvrRJL cUaioRZzUXEiAPh7MBVlAgAA Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 17360 Lines: 462 --- Jaegeuk Kim Samsung > -----Original Message----- > From: Namjae Jeon [mailto:linkinjeon@gmail.com] > Sent: Tuesday, October 09, 2012 12:52 PM > To: Jaegeuk Kim > Cc: 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 > > 2012/10/8, Jaegeuk Kim : > >> -----Original Message----- > >> From: Namjae Jeon [mailto:linkinjeon@gmail.com] > >> Sent: Monday, October 08, 2012 8:22 PM > >> To: Jaegeuk Kim > >> Cc: 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 > >> > >> 2012/10/8, Jaegeuk Kim : > >> >> -----Original Message----- > >> >> From: Namjae Jeon [mailto:linkinjeon@gmail.com] > >> >> Sent: Monday, October 08, 2012 7:00 PM > >> >> To: Jaegeuk Kim > >> >> Cc: 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 > >> >> > >> >> 2012/10/8, Jaegeuk Kim : > >> >> >> -----Original Message----- > >> >> >> From: Vyacheslav Dubeyko [mailto:slava@dubeyko.com] > >> >> >> Sent: Sunday, October 07, 2012 9:09 PM > >> >> >> To: Jaegeuk Kim > >> >> >> Cc: '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 > >> >> >> > >> >> >> Hi, > >> >> >> > >> >> >> On Oct 7, 2012, at 1:31 PM, Jaegeuk Kim wrote: > >> >> >> > >> >> >> >> -----Original Message----- > >> >> >> >> From: Marco Stornelli [mailto:marco.stornelli@gmail.com] > >> >> >> >> Sent: Sunday, October 07, 2012 4:10 PM > >> >> >> >> To: Jaegeuk Kim > >> >> >> >> Cc: Vyacheslav Dubeyko; jaegeuk.kim@samsung.com; 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 > >> >> >> >> > >> >> >> >> Il 06/10/2012 22:06, Jaegeuk Kim ha scritto: > >> >> >> >>> 2012-10-06 (토), 17:54 +0400, Vyacheslav Dubeyko: > >> >> >> >>>> Hi Jaegeuk, > >> >> >> >>> > >> >> >> >>> Hi. > >> >> >> >>> We know each other, right? :) > >> >> >> >>> > >> >> >> >>>> > >> >> >> >>>>> From: 김재극 > >> >> >> >>>>> To: viro@zeniv.linux.org.uk, 'Theodore Ts'o' > >> >> >> >>>>> , > >> >> >> >> gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, > >> >> >> >> chur.lee@samsung.com, > >> >> >> cm224.lee@samsung.com, > >> >> >> >> jaegeuk.kim@samsung.com, jooyoung.hwang@samsung.com > >> >> >> >>>>> Subject: [PATCH 00/16] f2fs: introduce flash-friendly file > >> >> >> >>>>> system > >> >> >> >>>>> Date: Fri, 05 Oct 2012 20:55:07 +0900 > >> >> >> >>>>> > >> >> >> >>>>> This is a new patch set for the f2fs file system. > >> >> >> >>>>> > >> >> >> >>>>> What is F2FS? > >> >> >> >>>>> ============= > >> >> >> >>>>> > >> >> >> >>>>> NAND flash memory-based storage devices, such as SSD, eMMC, > >> >> >> >>>>> and > >> >> >> >>>>> SD > >> >> >> >>>>> cards, have > >> >> >> >>>>> been widely being used for ranging from mobile to server > >> >> >> >>>>> systems. > >> >> >> >>>>> Since they are > >> >> >> >>>>> known to have different characteristics from the conventional > >> >> >> >>>>> rotational disks, > >> >> >> >>>>> a file system, an upper layer to the storage device, should > >> >> >> >>>>> adapt > >> >> >> >>>>> to > >> >> >> >>>>> the changes > >> >> >> >>>>> from the sketch. > >> >> >> >>>>> > >> >> >> >>>>> F2FS is a new file system carefully designed for the NAND > >> >> >> >>>>> flash > >> >> >> >>>>> memory-based storage > >> >> >> >>>>> devices. We chose a log structure file system approach, but > >> >> >> >>>>> we > >> >> >> >>>>> tried > >> >> >> >>>>> to adapt it > >> >> >> >>>>> to the new form of storage. Also we remedy some known issues > >> >> >> >>>>> of > >> >> >> >>>>> the > >> >> >> >>>>> very old log > >> >> >> >>>>> structured file system, such as snowball effect of wandering > >> >> >> >>>>> tree > >> >> >> >>>>> and high cleaning > >> >> >> >>>>> overhead. > >> >> >> >>>>> > >> >> >> >>>>> Because a NAND-based storage device shows different > >> >> >> >>>>> characteristics > >> >> >> >>>>> according to > >> >> >> >>>>> its internal geometry or flash memory management scheme aka > >> >> >> >>>>> FTL, > >> >> >> >>>>> we > >> >> >> >>>>> add various > >> >> >> >>>>> parameters not only for configuring on-disk layout, but also > >> >> >> >>>>> for > >> >> >> >>>>> selecting allocation > >> >> >> >>>>> and cleaning algorithms. > >> >> >> >>>>> > >> >> >> >>>> > >> >> >> >>>> What about F2FS performance? Could you share benchmarking > >> >> >> >>>> results > >> >> >> >>>> of > >> >> >> >>>> the new file system? > >> >> >> >>>> > >> >> >> >>>> It is very interesting the case of aged file system. How is > >> >> >> >>>> GC's > >> >> >> >>>> implementation efficient? Could > >> >> >> >> you share benchmarking results for the very aged file system > >> >> >> >> state? > >> >> >> >>>> > >> >> >> >>> > >> >> >> >>> Although I have benchmark results, currently I'd like to see > >> >> >> >>> the > >> >> >> >>> results > >> >> >> >>> measured by community as a black-box. As you know, the results > >> >> >> >>> are > >> >> >> >>> very > >> >> >> >>> dependent on the workloads and parameters, so I think it would > >> >> >> >>> be > >> >> >> >>> better > >> >> >> >>> to see other results for a while. > >> >> >> >>> Thanks, > >> >> >> >>> > >> >> >> >> > >> >> >> >> 1) Actually it's a strange approach. If you have got any results > >> >> >> >> you > >> >> >> >> should share them with the community explaining how (the > >> >> >> >> workload, > >> >> >> >> hw > >> >> >> >> and so on) your benchmark works and the specific condition. I > >> >> >> >> really > >> >> >> >> don't like the approach "I've got the results but I don't say > >> >> >> >> anything, > >> >> >> >> if you want a number, do it yourself". > >> >> >> > > >> >> >> > It's definitely right, and I meant *for a while*. > >> >> >> > I just wanted to avoid arguing with how to age file system in > >> >> >> > this > >> >> >> > time. > >> >> >> > Before then, I share the primitive results as follows. > >> >> >> > > >> >> >> > 1. iozone in Panda board > >> >> >> > - ARM A9 > >> >> >> > - DRAM : 1GB > >> >> >> > - Kernel: Linux 3.3 > >> >> >> > - Partition: 12GB (64GB Samsung eMMC) > >> >> >> > - Tested on 2GB file > >> >> >> > > >> >> >> > seq. read, seq. write, rand. read, rand. write > >> >> >> > - ext4: 30.753 17.066 5.06 4.15 > >> >> >> > - f2fs: 30.71 16.906 5.073 15.204 > >> >> >> > > >> >> >> > 2. iozone in Galaxy Nexus > >> >> >> > - DRAM : 1GB > >> >> >> > - Android 4.0.4_r1.2 > >> >> >> > - Kernel omap 3.0.8 > >> >> >> > - Partition: /data, 12GB > >> >> >> > - Tested on 2GB file > >> >> >> > > >> >> >> > seq. read, seq. write, rand. read, rand. write > >> >> >> > - ext4: 29.88 12.83 11.43 0.56 > >> >> >> > - f2fs: 29.70 13.34 10.79 12.82 > >> >> >> > > >> >> >> > >> >> >> > >> >> >> This is results for non-aged filesystem state. Am I correct? > >> >> >> > >> >> > > >> >> > Yes, right. > >> >> > > >> >> >> > >> >> >> > Due to the company secret, I expect to show other results after > >> >> >> > presenting f2fs at korea linux forum. > >> >> >> > > >> >> >> >> 2) For a new filesystem you should send the patches to > >> >> >> >> linux-fsdevel. > >> >> >> > > >> >> >> > Yes, that was totally my mistake. > >> >> >> > > >> >> >> >> 3) It's not clear the pros/cons of your filesystem, can you > >> >> >> >> share > >> >> >> >> with > >> >> >> >> us the main differences with the current fs already in mainline? > >> >> >> >> Or > >> >> >> >> is > >> >> >> >> it a company secret? > >> >> >> > > >> >> >> > After forum, I can share the slides, and I hope they will be > >> >> >> > useful > >> >> >> > to > >> >> >> > you. > >> >> >> > > >> >> >> > Instead, let me summarize at a glance compared with other file > >> >> >> > systems. > >> >> >> > Here are several log-structured file systems. > >> >> >> > Note that, F2FS operates on top of block device with > >> >> >> > consideration > >> >> >> > on > >> >> >> > the FTL behavior. > >> >> >> > So, JFFS2, YAFFS2, and UBIFS are out-of scope, since they are > >> >> >> > designed > >> >> >> > for raw NAND flash. > >> >> >> > LogFS is initially designed for raw NAND flash, but expanded to > >> >> >> > block > >> >> >> > device. > >> >> >> > But, I don't know whether it is stable or not. > >> >> >> > NILFS2 is one of major log-structured file systems, which > >> >> >> > supports > >> >> >> > multiple snap-shots. > >> >> >> > IMO, that feature is quite promising and important to users, but > >> >> >> > it > >> >> >> > may > >> >> >> > degrade the performance. > >> >> >> > There is a trade-off between functionalities and performance. > >> >> >> > F2FS chose high performance without any further fancy > >> >> >> > functionalities. > >> >> >> > > >> >> >> > >> >> >> Performance is a good goal. But fault-tolerance is also very > >> >> >> important > >> >> >> point. Filesystems are used by > >> >> >> users, so, it is very important to guarantee reliability of data > >> >> >> keeping. > >> >> >> Degradation of performance > >> >> >> by means of snapshots is arguable point. Snapshots can solve the > >> >> >> problem > >> >> >> not only some unpredictable > >> >> >> environmental issues but also user's erroneous behavior. > >> >> >> > >> >> > > >> >> > Yes, I agree. I concerned the multiple snapshot feature. > >> >> > Of course, fault-tolerance is very important, and file system should > >> >> > support > >> >> > it as you know as power-off-recovery. > >> >> > f2fs supports the recovery mechanism by adopting checkpoint similar > >> >> > to > >> >> > snapshot. > >> >> > But, f2fs does not support multiple snapshots for user convenience. > >> >> > I just focused on the performance, and absolutely, the multiple > >> >> > snapshot > >> >> > feature is also a good alternative approach. > >> >> > That may be a trade-off. > >> >> > > >> >> >> As I understand, it is not possible to have a perfect performance > >> >> >> in > >> >> >> all > >> >> >> possible workloads. Could you > >> >> >> point out what workloads are the best way of F2FS using? > >> >> > > >> >> > Basically I think the following workloads will be good for F2FS. > >> >> > - Many random writes : it's LFS nature > >> >> > - Small writes with frequent fsync : f2fs is optimized to reduce the > >> >> > fsync > >> >> > overhead. > >> >> > > >> >> >> > >> >> >> > Maybe or obviously it is possible to optimize ext4 or btrfs to > >> >> >> > flash > >> >> >> > storages. > >> >> >> > IMHO, however, they are originally designed for HDDs, so that it > >> >> >> > may > >> >> >> > or > >> >> >> > may not suffer from > >> >> >> fundamental designs. > >> >> >> > I don't know, but why not designing a new file system for flash > >> >> >> > storages > >> >> >> > as a counterpart? > >> >> >> > > >> >> >> > >> >> >> Yes, it is possible. But F2FS is not flash oriented filesystem as > >> >> >> JFFS2, > >> >> >> YAFFS2, UBIFS but block- > >> >> >> oriented filesystem. So, F2FS design is restricted by block-layer's > >> >> >> opportunities in the using of > >> >> >> flash storages' peculiarities. Could you point out key points of > >> >> >> F2FS > >> >> >> design that makes this design > >> >> >> fundamentally unique? > >> >> > > >> >> > 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. > >> Well, Format tool evaluates optimal block size whenever formatting? As > >> you know, The size of Flash Based storage device is increasing every > >> year. It means format time can be too long on larger devices(e.g. one > >> device, one parition). > > > > Every file systems will suffer from the long format time in such a huge > > device. > > And, I don't think the profiling time would not be scaled up, since it's > > unnecessary to scan whole device. > > After getting the size, we just can stop it. > The key point is that you should estimate correct optimal block size > of ftl with much less I/O at format time. Yes, exactly. > I am not sure it is possible. Why do you think like that? As I tested before, I could see a kind of patterns when writing just several tens of MB on eMMC. > And you should prove optimal block size is really correct on several > device per vendor device. Yes, it is correct, but unfortunately, I cannot prove for all the devices. You're arguing about heuristic vs. optimal approaches. IMHO, most file systems are based on a heuristic approach. And f2fs also adopts a heuristic approach, which means it tries to help FTL as much as possible, not cooperates with FTL directly. Furthermore, even though the default unit size is not optimal, I believe that it can be well operated in most cases. (Since most SSDs has 512KB of erase block size, so 2MB can cover 4-way SSDs.) Thanks, > > > > >> > But, IMO, from the viewpoint of performance, default configuration is > >> > quite > >> > enough now. > >> At default(after cleanly format), Would you share performance > >> difference between other log structured filesystems in comparison to > >> f2fs instead of ext4 ? > >> > > > > Actually, we've focused on ext4, so I have no results of other file systems > > measured on embedded systems. > > I'll test sooner or later, and report them. > Okay, Thanks Jaegeuk. > > > Thank you for valuable comments. > > > >> Thanks. > >> > > >> > ps) f2fs doesn't care about the flash page size, but considers garbage > >> > collection unit. > >> > > >> >> > >> >> Thanks. > >> >> > >> >> > > >> >> >> > >> >> >> With the best regards, > >> >> >> Vyacheslav Dubeyko. > >> >> >> > >> >> >> > >> >> >> >> > >> >> >> >> Marco > >> >> >> > > >> >> >> > --- > >> >> >> > Jaegeuk Kim > >> >> >> > Samsung > >> >> >> > > >> >> >> > -- > >> >> >> > To unsubscribe from this list: send the line "unsubscribe > >> >> >> > linux-kernel" > >> >> >> > in > >> >> >> > the body of a message to majordomo@vger.kernel.org > >> >> >> > More majordomo info at > >> >> >> > http://vger.kernel.org/majordomo-info.html > >> >> >> > Please read the FAQ at http://www.tux.org/lkml/ > >> >> > > >> >> > > >> >> > --- > >> >> > Jaegeuk Kim > >> >> > Samsung > >> >> > > >> >> > -- > >> >> > To unsubscribe from this list: send the line "unsubscribe > >> >> > linux-fsdevel" > >> >> > in > >> >> > the body of a message to majordomo@vger.kernel.org > >> >> > More majordomo info at http://vger.kernel.org/majordomo-info.html > >> >> > > >> > > >> > > >> > --- > >> > Jaegeuk Kim > >> > Samsung > >> > > >> > > >> > > > > > > > --- > > Jaegeuk Kim > > Samsung > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/