> -----Original Message----- > From: Lukáš Czerner [mailto:lczerner@xxxxxxxxxx] > Sent: Tuesday, October 09, 2012 8:01 PM > To: Jaegeuk Kim > Cc: 'Lukáš Czerner'; 'Namjae Jeon'; 'Vyacheslav Dubeyko'; 'Marco Stornelli'; 'Jaegeuk Kim'; 'Al Viro'; > tytso@xxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; chur.lee@xxxxxxxxxxx; > cm224.lee@xxxxxxxxxxx; jooyoung.hwang@xxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx > Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system > > On Tue, 9 Oct 2012, Jaegeuk Kim wrote: > > > Date: Tue, 09 Oct 2012 19:45:57 +0900 > > From: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx> > > To: 'Lukáš Czerner' <lczerner@xxxxxxxxxx> > > Cc: 'Namjae Jeon' <linkinjeon@xxxxxxxxx>, > > 'Vyacheslav Dubeyko' <slava@xxxxxxxxxxx>, > > 'Marco Stornelli' <marco.stornelli@xxxxxxxxx>, > > 'Jaegeuk Kim' <jaegeuk.kim@xxxxxxxxx>, > > 'Al Viro' <viro@xxxxxxxxxxxxxxxxxx>, tytso@xxxxxxx, > > gregkh@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > > chur.lee@xxxxxxxxxxx, cm224.lee@xxxxxxxxxxx, jooyoung.hwang@xxxxxxxxxxx, > > linux-fsdevel@xxxxxxxxxxxxxxx > > Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system > > > > > -----Original Message----- > > > From: linux-fsdevel-owner@xxxxxxxxxxxxxxx [mailto:linux-fsdevel-owner@xxxxxxxxxxxxxxx] On Behalf > Of > > > Luka? Czerner > > > Sent: Tuesday, October 09, 2012 5:32 PM > > > To: Jaegeuk Kim > > > Cc: 'Namjae Jeon'; 'Vyacheslav Dubeyko'; 'Marco Stornelli'; 'Jaegeuk Kim'; 'Al Viro'; > tytso@xxxxxxx; > > > gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; chur.lee@xxxxxxxxxxx; > cm224.lee@xxxxxxxxxxx; > > > jooyoung.hwang@xxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx > > > Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system > > > > > > On Mon, 8 Oct 2012, Jaegeuk Kim wrote: > > > > > > > Date: Mon, 08 Oct 2012 19:52:03 +0900 > > > > From: Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx> > > > > To: 'Namjae Jeon' <linkinjeon@xxxxxxxxx> > > > > Cc: 'Vyacheslav Dubeyko' <slava@xxxxxxxxxxx>, > > > > 'Marco Stornelli' <marco.stornelli@xxxxxxxxx>, > > > > 'Jaegeuk Kim' <jaegeuk.kim@xxxxxxxxx>, > > > > 'Al Viro' <viro@xxxxxxxxxxxxxxxxxx>, tytso@xxxxxxx, > > > > gregkh@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > > > > chur.lee@xxxxxxxxxxx, cm224.lee@xxxxxxxxxxx, jooyoung.hwang@xxxxxxxxxxx, > > > > linux-fsdevel@xxxxxxxxxxxxxxx > > > > Subject: RE: [PATCH 00/16] f2fs: introduce flash-friendly file system > > > > > > > > > -----Original Message----- > > > > > From: Namjae Jeon [mailto:linkinjeon@xxxxxxxxx] > > > > > Sent: Monday, October 08, 2012 7:00 PM > > > > > To: Jaegeuk Kim > > > > > Cc: Vyacheslav Dubeyko; Marco Stornelli; Jaegeuk Kim; Al Viro; tytso@xxxxxxx; > > > > > gregkh@xxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; chur.lee@xxxxxxxxxxx; > > > cm224.lee@xxxxxxxxxxx; > > > > > jooyoung.hwang@xxxxxxxxxxx; linux-fsdevel@xxxxxxxxxxxxxxx > > > > > Subject: Re: [PATCH 00/16] f2fs: introduce flash-friendly file system > > > > > > > > > > 2012/10/8, Jaegeuk Kim <jaegeuk.kim@xxxxxxxxxxx>: > > > > > >> -----Original Message----- > > > > > >> From: Vyacheslav Dubeyko [mailto:slava@xxxxxxxxxxx] > > > > > >> Sent: Sunday, October 07, 2012 9:09 PM > > > > > >> To: Jaegeuk Kim > > > > > >> Cc: 'Marco Stornelli'; 'Jaegeuk Kim'; 'Al Viro'; tytso@xxxxxxx; > > > > > >> gregkh@xxxxxxxxxxxxxxxxxxx; linux- > > > > > >> kernel@xxxxxxxxxxxxxxx; chur.lee@xxxxxxxxxxx; cm224.lee@xxxxxxxxxxx; > > > > > >> jooyoung.hwang@xxxxxxxxxxx; > > > > > >> linux-fsdevel@xxxxxxxxxxxxxxx > > > > > >> 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@xxxxxxxxx] > > > > > >> >> Sent: Sunday, October 07, 2012 4:10 PM > > > > > >> >> To: Jaegeuk Kim > > > > > >> >> Cc: Vyacheslav Dubeyko; jaegeuk.kim@xxxxxxxxxxx; Al Viro; > > > > > >> >> tytso@xxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx; > > > > > >> >> linux-kernel@xxxxxxxxxxxxxxx; chur.lee@xxxxxxxxxxx; > > > > > >> >> cm224.lee@xxxxxxxxxxx; > > > > > >> jooyoung.hwang@xxxxxxxxxxx; > > > > > >> >> linux-fsdevel@xxxxxxxxxxxxxxx > > > > > >> >> 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 <jaegeuk.kim@xxxxxxxxxxx> > > > > > >> >>>>> To: viro@xxxxxxxxxxxxxxxxxx, 'Theodore Ts'o' <tytso@xxxxxxx>, > > > > > >> >> gregkh@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, > > > > > >> >> chur.lee@xxxxxxxxxxx, > > > > > >> cm224.lee@xxxxxxxxxxx, > > > > > >> >> jaegeuk.kim@xxxxxxxxxxx, jooyoung.hwang@xxxxxxxxxxx > > > > > >> >>>>> 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. > > > > 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? 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 > > > > > > > > > Thanks! > > > -Lukas > > > > > > > > > > > > > > > > > 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@xxxxxxxxxxxxxxx > > > > > >> > 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@xxxxxxxxxxxxxxx > > > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > > > > > > > > > > > --- > > > > Jaegeuk Kim > > > > Samsung > > > > > > > > > > > > -- > > > > To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in > > > > the body of a message to majordomo@xxxxxxxxxxxxxxx > > > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > > > > > > > > > > --- > > Jaegeuk Kim > > Samsung > > > > > > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
