Slow NAND + JFFS2

Slow NAND + JFFS2

[Semih Hazar]

Hi,

I'm using a 256 MiB NAND Flash from ST -> Manufacturer ID: 0x20, Chip 
ID: 0xda (ST Micro NAND 256MiB 3,3V 8-bit) with JFFS2. The filesystem is 
mounted as rootfs and the size is around 60 megs.

Filesystem operations seem very slow to me. Such as:

It takes almost 1 and a half minutes to copy a 30 meg file.
Mounting the filesystem takes around 1 minute.

# ls -lh
-rw-r--r--    1 root     root        30.3M Jan  1 00:05 gcc.tgz
# time cp gcc.tgz 1
real    1m 22.37s
user    0m 0.09s
sys     1m 22.22s
#


This seemed really slow to me, but I don't have any other benchmarks. 
Can someone comment on these values ?

The processor is at32ap7000 from Atmel, running at 160 MHz.
I'm running kernel 2.6.20.1 with cpu related patches from Atmel and our 
own nand patches which are almost the replica of at91_nand.c (I can send 
it if you need)

I also changed the read enable and write enable pulse timings according 
to the minimum values stated in NAND flash's datasheet.

If this copy/mount time are really slow as I think, where should I check 
? Is this a JFFS2 related issue or should I try to find some problems in 
our nand driver or ... ?

Best regards,
Semih Hazar

Re: Slow NAND + JFFS2

[Josh Boyer]

On 4/25/07, Semih Hazar <semih.hazar@indefia.com> wrote:
> Hi,
>
> I'm using a 256 MiB NAND Flash from ST -> Manufacturer ID: 0x20, Chip
> ID: 0xda (ST Micro NAND 256MiB 3,3V 8-bit) with JFFS2. The filesystem is
> mounted as rootfs and the size is around 60 megs.
>
> Filesystem operations seem very slow to me. Such as:
>
> It takes almost 1 and a half minutes to copy a 30 meg file.
> Mounting the filesystem takes around 1 minute.

Given your CPU speed and the size of the files involved, these timings
seem to be normal to me.

You might want to try using summary support to speed up mount time (at
the cost of some additional used space).  I'm not entirely sure you
can speed up the copy time of your file though.

josh

Re: Slow NAND + JFFS2

[akorolev]

Hi,

You may try to clarify if compression is off.
> Hi,
>
> I'm using a 256 MiB NAND Flash from ST -> Manufacturer ID: 0x20, Chip 
> ID: 0xda (ST Micro NAND 256MiB 3,3V 8-bit) with JFFS2. The filesystem is 
> mounted as rootfs and the size is around 60 megs.
>
> Filesystem operations seem very slow to me. Such as:
>
> It takes almost 1 and a half minutes to copy a 30 meg file.
> Mounting the filesystem takes around 1 minute.
>
> # ls -lh
> -rw-r--r--    1 root     root        30.3M Jan  1 00:05 gcc.tgz
> # time cp gcc.tgz 1
> real    1m 22.37s
> user    0m 0.09s
> sys     1m 22.22s
> #
>
>
> This seemed really slow to me, but I don't have any other benchmarks. 
> Can someone comment on these values ?
>
> The processor is at32ap7000 from Atmel, running at 160 MHz.
> I'm running kernel 2.6.20.1 with cpu related patches from Atmel and our 
> own nand patches which are almost the replica of at91_nand.c (I can send 
> it if you need)
>
> I also changed the read enable and write enable pulse timings according 
> to the minimum values stated in NAND flash's datasheet.
>
> If this copy/mount time are really slow as I think, where should I check 
> ? Is this a JFFS2 related issue or should I try to find some problems in 
> our nand driver or ... ?
>
> Best regards,
> Semih Hazar
>
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
>
>   

Re: Slow NAND + JFFS2

[Semih Hazar]

akorolev wrote:
> You may try to clarify if compression is off.
Setting compression mode to "no compression" speeds it a lot.
This time copying a 40 meg file takes 21 seconds. (from NAND to NAND as 
in the first case)

Thanks

Re: Slow NAND + JFFS2

[Haavard Skinnemoen]

On Wed, 25 Apr 2007 18:36:26 +0300
Semih Hazar <semih.hazar@indefia.com> wrote:

> akorolev wrote:
> > You may try to clarify if compression is off.  
> Setting compression mode to "no compression" speeds it a lot.
> This time copying a 40 meg file takes 21 seconds. (from NAND to NAND as 
> in the first case)

Interesting. I suspect the zlib code might thrash the TLB quite a bit
on the ap7000 because of the rather large workspace struct which is
allocated using vmalloc().

Until we get around to supporting larger page sizes for vmalloc, could
you try a different compressor (assuming you're currently using zlib)?

Haavard

Re: Slow NAND + JFFS2

[Semih Hazar]

Haavard Skinnemoen wrote:
> Interesting. I suspect the zlib code might thrash the TLB quite a bit
> on the ap7000 because of the rather large workspace struct which is
> allocated using vmalloc().
>
> Until we get around to supporting larger page sizes for vmalloc, could
> you try a different compressor (assuming you're currently using zlib)?
>   
Zlib or rtime, not sure. I'll try other compressors and let you know the 
benchmarks.