From: "Lukáš Czerner" <lczerner@redhat.com>
To: Jaegeuk Kim <jaegeuk.kim@samsung.com>
Cc: "'Lukáš Czerner'" <lczerner@redhat.com>,
"'Namjae Jeon'" <linkinjeon@gmail.com>,
"'Vyacheslav Dubeyko'" <slava@dubeyko.com>,
"'Marco Stornelli'" <marco.stornelli@gmail.com>,
"'Jaegeuk Kim'" <jaegeuk.kim@gmail.com>,
"'Al Viro'" <viro@zeniv.linux.org.uk>,
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
Date: Tue, 9 Oct 2012 14:39:06 +0200 (CEST) [thread overview]
Message-ID: <alpine.LFD.2.00.1210091437460.17156@dhcp-1-104.brq.redhat.com> (raw)
In-Reply-To: <008301cda615$ca3b9980$5eb2cc80$%kim@samsung.com>
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
next prev parent reply other threads:[~2012-10-09 12:39 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <415E76CC-A53D-4643-88AB-3D7D7DC56F98@dubeyko.com>
2012-10-06 13:54 ` [PATCH 00/16] f2fs: introduce flash-friendly file system Vyacheslav Dubeyko
2012-10-06 20:06 ` Jaegeuk Kim
2012-10-07 7:09 ` Marco Stornelli
2012-10-07 9:31 ` Jaegeuk Kim
2012-10-07 12:08 ` Vyacheslav Dubeyko
2012-10-08 8:25 ` Jaegeuk Kim
2012-10-08 9:59 ` Namjae Jeon
2012-10-08 10:52 ` Jaegeuk Kim
2012-10-08 11:21 ` Namjae Jeon
2012-10-08 12:11 ` Jaegeuk Kim
2012-10-09 3:52 ` Namjae Jeon
2012-10-09 8:00 ` Jaegeuk Kim
2012-10-09 8:31 ` Lukáš Czerner
2012-10-09 10:45 ` Jaegeuk Kim
2012-10-09 11:01 ` Lukáš Czerner
2012-10-09 12:01 ` Jaegeuk Kim
2012-10-09 12:39 ` Lukáš Czerner [this message]
2012-10-09 13:10 ` Jaegeuk Kim
2012-10-09 21:20 ` Dave Chinner
2012-10-10 2:32 ` Jaegeuk Kim
2012-10-10 4:53 ` Theodore Ts'o
2012-10-12 20:55 ` Arnd Bergmann
2012-10-10 10:36 ` David Woodhouse
2012-10-12 20:58 ` Arnd Bergmann
2012-10-13 4:26 ` Namjae Jeon
2012-10-13 12:37 ` Jaegeuk Kim
2012-10-17 11:12 ` Namjae Jeon
[not found] ` <000001cdacef$b2f6eaa0$18e4bfe0$%kim@samsung.com>
2012-10-18 13:39 ` Vyacheslav Dubeyko
2012-10-18 22:14 ` Jaegeuk Kim
2012-10-19 9:20 ` NeilBrown
2012-10-08 19:22 ` Vyacheslav Dubeyko
2012-10-09 7:08 ` Jaegeuk Kim
2012-10-09 19:53 ` Jooyoung Hwang
2012-10-10 8:05 ` Vyacheslav Dubeyko
2012-10-10 9:02 ` Theodore Ts'o
2012-10-10 11:52 ` SQLite on flash (was: [PATCH 00/16] f2fs: introduce flash-friendly file system) Clemens Ladisch
2012-10-10 7:57 ` [PATCH 00/16] f2fs: introduce flash-friendly file system Vyacheslav Dubeyko
2012-10-10 9:43 ` Jaegeuk Kim
2012-10-11 3:14 ` Namjae Jeon
[not found] ` <CAN863PuyMkSZtZCvqX+kwei9v=rnbBYVYr3TqBXF_6uxwJe2_Q@mail.gmail.com>
2012-10-17 11:13 ` Namjae Jeon
2012-10-17 23:06 ` Changman Lee
2012-10-12 12:30 ` Vyacheslav Dubeyko
2012-10-12 14:25 ` Jaegeuk Kim
2012-10-07 10:15 ` Vyacheslav Dubeyko
2012-10-05 11:55 김재극
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