How stable is jffs2 summarize option?

How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Hi,

to reduce boot time of a device I want to use the jffs2 summarize option on my 
root file system. Currently 'm using Linux 2.6.24 on that specific device and 
the summarize option is marked as "experimental", so I wonder if it is stable 
enough for a productive system?
Are there any well known devices that use this option, too?
Do I have to use a newer kernel version?

Thanks for any information

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

And is this an error, a warning or just debug output:
jffs2_sum_write_sumnode: Not enough space for summary, padsize -45


Am Monday 31 May 2010 15:03:42 schrieb Thorsten Mühlfelder:
> Hi,
>
> to reduce boot time of a device I want to use the jffs2 summarize option on
> my root file system. Currently 'm using Linux 2.6.24 on that specific
> device and the summarize option is marked as "experimental", so I wonder if
> it is stable enough for a productive system?
> Are there any well known devices that use this option, too?
> Do I have to use a newer kernel version?
>
> Thanks for any information
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/



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--
____________________________________________________
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Hard- und Softwareentwicklung

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Re: How stable is jffs2 summarize option?

[Vitaly Wool]

Hi,

2010/5/31 Thorsten Mühlfelder <muehlfelder@enertex.de>:

> Are there any well known devices that use this option, too?

Yes, there are :)

> Do I have to use a newer kernel version?

Better do so :)

~Vitaly

Re: How stable is jffs2 summarize option?

[Vitaly Wool]

2010/5/31 Thorsten Mühlfelder <muehlfelder@enertex.de>:
> And is this an error, a warning or just debug output:
> jffs2_sum_write_sumnode: Not enough space for summary, padsize -45

That's completely harmless.

~Vitaly

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Am Monday 31 May 2010 21:59:56 schrieb Vitaly Wool:
> > Do I have to use a newer kernel version?
>
> Better do so :)

After checking the Linux ChangeLogs at http://kernelnewbies.org/Linux26Changes 
I did not find any changes related to JFFS2 summary option, so I don't think 
a newer kernel is needed ;-)

Re: How stable is jffs2 summarize option?

[David Woodhouse]

On Mon, 2010-05-31 at 15:03 +0200, Thorsten Mühlfelder wrote:
> to reduce boot time of a device I want to use the jffs2 summarize option on my 
> root file system. Currently 'm using Linux 2.6.24 on that specific device and 
> the summarize option is marked as "experimental", so I wonder if it is stable 
> enough for a productive system?
> Are there any well known devices that use this option, too?
> Do I have to use a newer kernel version?

There are other reasons why you should update from 2.6.24 if you're
using JFFS2, but I don't think the summary code has changed much since
then. The only reason it was still marked as 'experimental' is because I
wanted to optimise the on-medium format.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Am Tuesday 01 June 2010 11:15:15 schrieb David Woodhouse:
> On Mon, 2010-05-31 at 15:03 +0200, Thorsten Mühlfelder wrote:
> > to reduce boot time of a device I want to use the jffs2 summarize option
> > on my root file system. Currently 'm using Linux 2.6.24 on that specific
> > device and the summarize option is marked as "experimental", so I wonder
> > if it is stable enough for a productive system?
> > Are there any well known devices that use this option, too?
> > Do I have to use a newer kernel version?
>
> There are other reasons why you should update from 2.6.24 if you're
> using JFFS2, but I don't think the summary code has changed much since
> then. The only reason it was still marked as 'experimental' is because I
> wanted to optimise the on-medium format.

Hi,

and what do you think about switching to yaffs2? I know it is developed 
elsewhere, but it seems to be a good alternative to jffs2+summary and 
probably switching is easier than to ubifs.

Best regards
Thorsten

Re: How stable is jffs2 summarize option?

[David Woodhouse]

On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> and what do you think about switching to yaffs2? I know it is developed 
> elsewhere, but it seems to be a good alternative to jffs2+summary and 
> probably switching is easier than to ubifs. 

Why would you think that switching to something that isn't part of the
Linux kernel would be easier than switching to ubifs? That seems... odd.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation

Re: How stable is jffs2 summarize option?

[Vitaly Wool]

Hi Thorsten,

2010/6/1 Thorsten Mühlfelder <muehlfelder@enertex.de>:

> and what do you think about switching to yaffs2? I know it is developed
> elsewhere, but it seems to be a good alternative to jffs2+summary and
> probably switching is easier than to ubifs.

Can you please share your reasons why you're considering switching first? :)

~Vitaly

Re: How stable is jffs2 summarize option?

[Joakim Tjernlund]

>
> On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> > and what do you think about switching to yaffs2? I know it is developed
> > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > probably switching is easier than to ubifs.
>
> Why would you think that switching to something that isn't part of the
> Linux kernel would be easier than switching to ubifs? That seems... odd.

Yes, if ubifs doesn't fit, perhaps have a look at the recently added
logfs?

    Jocke

BTW, I once tried JFFS2 summary and it didn't make much of a difference for us.

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Am Tuesday 01 June 2010 11:33:08 schrieb David Woodhouse:
> On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> > and what do you think about switching to yaffs2? I know it is developed
> > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > probably switching is easier than to ubifs.
>
> Why would you think that switching to something that isn't part of the
> Linux kernel would be easier than switching to ubifs? That seems... odd.

Because getting yaffs2 source and patching the kernel only was 2 commands and 
no single additional tool is needed. Just boot from USB stick and run:
flash_eraseall /dev/mtd1
mount -t yaffs2 /dev/mtdblock1 /mnt/device-root
tar xvf root-filesystem.tar -C /mnt/device-root

;-)

Re: How stable is jffs2 summarize option?

[Ladislav Michl]

On Tue, Jun 01, 2010 at 09:28:17AM +0200, Thorsten M?hlfelder wrote:
> After checking the Linux ChangeLogs at http://kernelnewbies.org/Linux26Changes 
> I did not find any changes related to JFFS2 summary option, so I don't think 
> a newer kernel is needed ;-)

Above summary is meant to list user and kernel developer visible changes only.
You may want to check real changelog: http://git.infradead.org/mtd-2.6.git

	l.

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Am Tuesday 01 June 2010 11:50:06 schrieb Joakim Tjernlund:
> > On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> > > and what do you think about switching to yaffs2? I know it is developed
> > > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > > probably switching is easier than to ubifs.
> >
> > Why would you think that switching to something that isn't part of the
> > Linux kernel would be easier than switching to ubifs? That seems... odd.
>
> Yes, if ubifs doesn't fit, perhaps have a look at the recently added
> logfs?
>
>     Jocke
>
> BTW, I once tried JFFS2 summary and it didn't make much of a difference for
> us.

JFFS2 summary has reduced the mount time of my 500 MB root partition from 
around 50 seconds to 10 seconds.

yaffs2 has a mount time of ~3 seconds and it seems it has faster read access 
because whole boot time is reduced by ~30 seconds (compared to jffs2 
summary).

I did not try ubifs yet.

AFAIK LogFS is still experimental?

Re: How stable is jffs2 summarize option?

[Thorsten Mühlfelder]

Am Tuesday 01 June 2010 11:47:27 schrieb Vitaly Wool:
> Hi Thorsten,
>
> 2010/6/1 Thorsten Mühlfelder <muehlfelder@enertex.de>:
> > and what do you think about switching to yaffs2? I know it is developed
> > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > probably switching is easier than to ubifs.
>
> Can you please share your reasons why you're considering switching first?
> :)
>

Hi Vitaly,
1. We've used JFFS2 without summary until now, but now I have to reduce the 
boot time to the minimum possible. So first idea was the summary option, 
because other than slow mount times JFFS2 has worked OK. But if I do a major 
change now, why not switch to a more modern FS which will fasten boot up even 
more? ;-)

Additional requirements:
Sometimes it's written to the root FS and the device must be aware of power 
failures during write. I guess all the mentioned FS can handle this quite 
well.

Greetings
Thorsten

Re: How stable is jffs2 summarize option?

[David Woodhouse]

On Tue, 2010-06-01 at 11:50 +0200, Joakim Tjernlund wrote:
> >
> > On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> > > and what do you think about switching to yaffs2? I know it is developed
> > > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > > probably switching is easier than to ubifs.
> >
> > Why would you think that switching to something that isn't part of the
> > Linux kernel would be easier than switching to ubifs? That seems... odd.
> 
> Yes, if ubifs doesn't fit, perhaps have a look at the recently added
> logfs?
> 
>     Jocke
> 
> BTW, I once tried JFFS2 summary and it didn't make much of a difference for us.

Did you use 'sumtool' after creating your images? For reasons which are
now lost in the mists of time, that support wasn't just added directly
to mkfs.jffs2.

-- 
David Woodhouse                            Open Source Technology Centre
David.Woodhouse@intel.com                              Intel Corporation

Re: How stable is jffs2 summarize option?

[Joakim Tjernlund]

David Woodhouse <dwmw2@infradead.org> wrote on 2010/06/01 12:38:57:
>
> On Tue, 2010-06-01 at 11:50 +0200, Joakim Tjernlund wrote:
> > >
> > > On Tue, 2010-06-01 at 11:26 +0200, Thorsten Mühlfelder wrote:
> > > > and what do you think about switching to yaffs2? I know it is developed
> > > > elsewhere, but it seems to be a good alternative to jffs2+summary and
> > > > probably switching is easier than to ubifs.
> > >
> > > Why would you think that switching to something that isn't part of the
> > > Linux kernel would be easier than switching to ubifs? That seems... odd.
> >
> > Yes, if ubifs doesn't fit, perhaps have a look at the recently added
> > logfs?
> >
> >     Jocke
> >
> > BTW, I once tried JFFS2 summary and it didn't make much of a difference for us.
>
> Did you use 'sumtool' after creating your images? For reasons which are
> now lost in the mists of time, that support wasn't just added directly
> to mkfs.jffs2.

This was some years ago but I cannot recall using 'sumtool'. Also
our NOR FS is between 128 and 64 MB so perhaps it is too small to benefit
from summary?