[U-Boot-Users] Performance in Booting Linux w/ Device Tree via U-Boot out of JFFS2 on NAND

[U-Boot-Users] Performance in Booting Linux w/ Device Tree via U-Boot out of JFFS2 on NAND

[Mark Craske]

Hi Grant,

 

I  have a custom board that only has NAND flash, so my JFFS2 file
systems are in NAND.

 

You say in your mail item of Fri, 07 Mar 2008 17:09:42 -0800 that you
are using

u-boot/fs/jffs2/jffs2_nand_1pass.c from u-boot (1.3.2-rc3).  However,
when I change

the u-boot/fs/jffs2/Makefile to build jffs2_nand_1pass.o instead of
jffs2_1pass.o it

does not build.

 

Have you modified jffs2_nand_1pass.c from the version in 1.3.2-rc3?

 

Regards, Mark

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[U-Boot-Users] Performance in Booting Linux w/ Device Tree via U-Boot out of JFFS2 on NAND

[Grant Erickson]

On 6/26/08 8:33 AM, Mark Craske wrote:
> I  have a custom board that only has NAND flash, so my JFFS2 file systems are
> in NAND.
>  
> You say in your mail item of Fri, 07 Mar 2008 17:09:42 -0800 that you are
> using
> u-boot/fs/jffs2/jffs2_nand_1pass.c from u-boot (1.3.2-rc3). However, when I
> change
> the u-boot/fs/jffs2/Makefile to build jffs2_nand_1pass.o instead of
> jffs2_1pass.o it
> does not build.
>  
> Have you modified jffs2_nand_1pass.c from the version in 1.3.2-rc3?

Mark:

At this point, for performance reasons, I abandoned any effort to use JFFS2
out of u-boot to boot images via 'fsload'.

So, as of today, I am running u-boot-1.3.3 and am booting a boot.itb
"multi-image" containing a compressed Linux kernel + FDT DTB out of NAND
using 'nboot':

    => printenv bootaddr bootcmd boot0 boot1
    bootaddr=800000
    bootcmd=run boot0 || run boot1 || reset
    boot0=nboot.i ${bootaddr} 0 0 && setenv bootargs root=/dev/mtdblock9 &&
        run addjffs2 addtty && bootm ${bootaddr}
    boot1=nboot.i ${bootaddr} 0 1C00000 && setenv bootargs
        root=/dev/mtdblock11 && run addjffs2 addtty && bootm ${bootaddr}

During the time I was evaluating JFFS2 on the AMCC PowerPC 405EXr Haleakala
board, I do not recall having any compilation issues or having to tweak the
build beyond the necessary CONFIG_/CFG_ settings.

Regards,

Grant

[U-Boot-Users] Performance in Booting Linux w/ Device Tree via U-Boot out of JFFS2 on NAND

[Grant Erickson]

On 3/6/08 9:30 AM, Grant Erickson wrote:
> I am continuing some experiments in booting Linux w/ a flattened device tree
> via u-boot (1.3.2-rc3) from JFFS2 on NAND on an AMCC "Haleakala" board and am
> curious if anyone has come up with some quantitative performance
> characterizations of the various options (in all cases, u-boot lives on NOR
> flash). The options I am evaluating are:
> 
> 1) Put uImage and haleakala.dtb in their own "raw" NAND slices and boot with
>    u-boot nand commands:
> 
> [ ... details omitted ... ]
> 
> Qualitative performance: Nearly instantaneous.
> 
> As expected, in this case the qualitative, subjective time to seeing "Linux
> version 2.6.25-rc3-00951-g6514352-dirty ..." is nearly instantaneous.
> 
> 2) Put uImage and haleakala.dtb as files in /boot in the ~12 MB JFFS2 root
>    file system image in the ~60 MB "root" NAND slice and boot with u-boot
>    fsload commands:
> 
> [ ... details omitted ... ]
> 
> 2a) With CFG_JFFS2_SORT_FRAGMENTS enabled.
> 
> Qualitative performance: Takes the better part of 30-35 minutes.
> 
> As expected with the in-documentation warnings about CFG_JFFS2_SORT_FRAGMENTS
> and looking at the code in u-boot/fs/jffs2/jffs2_nand_1pass.c, the
> qualitative, subjective time to seeing the Linux version banner is slow, slow
> and slow.
> 
> 2b) With CFG_JFFS2_SORT_FRAGMENTS disabled.
> 
> Qualitative performance: Takes about 30 seconds to two minutes.
> 
> 3) This is a hybrid approach that I am setting up right now and is where I am
> curious if anyone has done plots of fsload time on JFFS2 + NAND relative to
> file system size.
> 
> Here, we use a separate 4 MB "/boot" JFFS2 file system for uImage and
> haleakala.dtb files and a 60 MB "/" JFFS2 file system for the root file
> system.
> 
> [ ... details omitted ... ]
> 
> 3a) With CFG_JFFS2_SORT_FRAGMENTS enabled.
> 
> Shouldn't be necessary since the /boot file system would only ever be accessed
> read-only and updated by nandwrite, not individual file updates.
> 
> 3b) With CFG_JFFS2_SORT_FRAGMENTS disabled.
> 
> Qualitative performance: TBD <= 2b

For what it's worth, the results of (3b) above with a 4 MB "boot" JFFS2 file
system were the same as (2b) where "/boot" was just a subdirectory of the 12
MB (62 MB total NAND space) "/" JFFS2 file system:

In short, qualitative performance: Takes about 30 seconds to two minutes.

So, with CFG_JFFS2_SORT_FRAGMENTS disabled it would appear that fsload on
JFFS2 is O(1) with respect to one or all of: file system size, inodes or
dirents in the 4 MB to 64 MB range.

Regards,

Grant