[U-Boot] JFFS2-Summary support for u-boot

[U-Boot] JFFS2-Summary support for u-boot

[Michael Lawnick]

Hi *,

please feel free to correct me if I tell sh**:
As far as I was told, bad JFFS2 boot performance of u-boot is result of not
supporting summary. (Because there is no JFFS2 but only JFFS support?)

So my question:
Has anybody done or is planning in next time (~weeks) to add summary support for
u-boot JFFS2? We need a file system on 32MB NOR flash with wear leveling and
acceptable boot time. Ubi is currently not supported for NOR, JFFS2 slow, ... :-(

TIA
Kind Regards,
M.Lawnick

[U-Boot] JFFS2-Summary support for u-boot

[Joakim Tjernlund]

On Mon, 2008-09-29 at 08:45 +0000, Michael Lawnick wrote:
> Hi *,
> 
> please feel free to correct me if I tell sh**:
> As far as I was told, bad JFFS2 boot performance of u-boot is result of not
> supporting summary. (Because there is no JFFS2 but only JFFS support?)

It is not missing SUMMARY, it is excessive scanning of empty flash
blocks. Look at jffs2/scan.c, it only scan the first 4KB or before
declaring the block empty.

 Jocke

[U-Boot] JFFS2-Summary support for u-boot

[Michael Lawnick]

Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:

> 
> On Mon, 2008-09-29 at 08:45 +0000, Michael Lawnick wrote:
> > Hi *,
> > 
> > please feel free to correct me if I tell sh**:
> > As far as I was told, bad JFFS2 boot performance of u-boot is result of not
> > supporting summary. (Because there is no JFFS2 but only JFFS support?)
> 
> It is not missing SUMMARY, it is excessive scanning of empty flash
> blocks. Look at jffs2/scan.c, it only scan the first 4KB or before
> declaring the block empty.

Ok, did I get you correct:
The performance difference between u-boot and linux is based on skipping
senseless scans of empty blocks?
I've taken a little look into scan.c
The comment "The code lacks more or less any comment, and is still arcane and
difficult to read in places." doesn't make me happy.

Has anybody tried to (and succeeded in) speed up u-boot?

Michael

[U-Boot] JFFS2-Summary support for u-boot

[Joakim Tjernlund]

On Mon, 2008-09-29 at 11:34 +0000, Michael Lawnick wrote:
> Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:
> 
> > 
> > On Mon, 2008-09-29 at 08:45 +0000, Michael Lawnick wrote:
> > > Hi *,
> > > 
> > > please feel free to correct me if I tell sh**:
> > > As far as I was told, bad JFFS2 boot performance of u-boot is result of not
> > > supporting summary. (Because there is no JFFS2 but only JFFS support?)
> > 
> > It is not missing SUMMARY, it is excessive scanning of empty flash
> > blocks. Look at jffs2/scan.c, it only scan the first 4KB or before
> > declaring the block empty.
> 
> Ok, did I get you correct:
> The performance difference between u-boot and linux is based on skipping
> senseless scans of empty blocks?
> I've taken a little look into scan.c
> The comment "The code lacks more or less any comment, and is still arcane and
> difficult to read in places." doesn't make me happy.
> 
> Has anybody tried to (and succeeded in) speed up u-boot?

Yes, there was an attempt some time ago(months or a year, dunno) where
someone had improved scanning dramatically, patch was posted to the
u-boot list. Can't remember who though.

 Jocke 

[U-Boot] JFFS2-Summary support for u-boot

[Michael Lawnick]

Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:

> > Has anybody tried to (and succeeded in) speed up u-boot?
> 
> Yes, there was an attempt some time ago(months or a year, dunno) where
> someone had improved scanning dramatically, patch was posted to the
> u-boot list. Can't remember who though.

Seems to be the thread 'jffs2 fsload - SOLVED.' from 12 Jan 03:14 Dan Merillat.
As I've looke into the patch, it seems not to have found its way into u-boot.
Any(body any) idea why?

Michael

[U-Boot] JFFS2-Summary support for u-boot

[Joakim Tjernlund]

On Mon, 2008-09-29 at 12:49 +0000, Michael Lawnick wrote:
> Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:
> 
> > > Has anybody tried to (and succeeded in) speed up u-boot?
> > 
> > Yes, there was an attempt some time ago(months or a year, dunno) where
> > someone had improved scanning dramatically, patch was posted to the
> > u-boot list. Can't remember who though.
> 
> Seems to be the thread 'jffs2 fsload - SOLVED.' from 12 Jan 03:14 Dan Merillat.
> As I've looke into the patch, it seems not to have found its way into u-boot.

Can't remember, possibly it was a hack.

 Jocke

[U-Boot] JFFS2-Summary support for u-boot

[Detlev Zundel]

Hi Michael,

> Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:
>
>> 
>> On Mon, 2008-09-29 at 08:45 +0000, Michael Lawnick wrote:
>> > Hi *,
>> > 
>> > please feel free to correct me if I tell sh**:
>> > As far as I was told, bad JFFS2 boot performance of u-boot is result of not
>> > supporting summary. (Because there is no JFFS2 but only JFFS support?)
>> 
>> It is not missing SUMMARY, it is excessive scanning of empty flash
>> blocks. Look at jffs2/scan.c, it only scan the first 4KB or before
>> declaring the block empty.
>
> Ok, did I get you correct:
> The performance difference between u-boot and linux is based on skipping
> senseless scans of empty blocks?
> I've taken a little look into scan.c
> The comment "The code lacks more or less any comment, and is still arcane and
> difficult to read in places." doesn't make me happy.
>
> Has anybody tried to (and succeeded in) speed up u-boot?

We are currently working on such a speedup bringing U-Boot up to par
with Linux.  I am confident that we can post our results in the next
week.

Cheers
  Detlev

PS: Wow, message-mode in Emacs wants a confirmation sending an email to
    you as your address looks bogus ;)

-- 
Emacs is the way to purify your soul using garbage collection.
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de

[U-Boot] JFFS2-Summary support for u-boot

[Michael Lawnick]

Detlev Zundel schrieb:
>> Has anybody tried to (and succeeded in) speed up u-boot?
> 
> We are currently working on such a speedup bringing U-Boot up to par
> with Linux.  I am confident that we can post our results in the next
> week.
> 
Sounds promising!

> PS: Wow, message-mode in Emacs wants a confirmation sending an email to
>     you as your address looks bogus ;)
> 

Address is valid and in use. This nospam_ kept away spam for some time.
Seems some filters sorted it out, others removed it.

Michael

[U-Boot] JFFS2-Summary support for u-boot

[Michael Lawnick]

Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:

> Can't remember, possibly it was a hack.
> 
Seems so. I tried to put it in my 1.3.3, but 'ls' never returns :-(

So I will wait for Detlev Zundel.

Michael

[U-Boot] JFFS2-Summary support for u-boot

[Detlev Zundel]

Hi Michael,

> Joakim Tjernlund <joakim.tjernlund <at> transmode.se> writes:
>
>> Can't remember, possibly it was a hack.
>> 
> Seems so. I tried to put it in my 1.3.3, but 'ls' never returns :-(
>
> So I will wait for Detlev Zundel.

Actually someone doing the development for DENX will post the code, but
it will not be me ;)

The code should hit the mailing list any day now.  The speed
improvements are pretty drastic, although dependant on the actual file
system.  Improvements by factors of 4 have been measured however...

Cheers
  Detlev

-- 
"The number you have dialed is imaginary. Please rotate your phone 90
degrees and try again."
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de