On Friday 06 October 2006 01:55, Vitaly Wool wrote:
> Gents,
>
> Here the basic performance measurements for JFFS2 and YAFFS2 as of
> 5/10/2006 are presented. The measurements were performed on the PNX4008
> platform which is a 208 MHz CPU ARM926-based Philips board. The 2k page
> flash is the real NAND flash (20MiB partition); the 512b flash is
> nandsim (8 MB partition).

Thanx for doing this Vitaly.  Numbers always help.

Can you also post details of the tests you used?

JFFS2 speed has come a long way... kudos to the JFFS2 team.

>
>
>     Measurement results
>
> 2K page NAND flash
> ==================
>
>                         Write big file  Write folder    Mount
> ---------------------+---------------------------------------
> YAFFS2               |  123.4 s         93.7 s          0.8 s
> JFFS2 w/o summary    |  66.5 s          18.0 s          7.6 s
> JFFS2 w/ summary     |  68.0 s          28.9 s          0.6 s

I find it hard to understand why there should be such a difference in the 
write speed (JFFS2 is 2x YAFFS2) because, apart form gc effects, they should 
both be writing pretty much the same amount to flash and doing equal amounts 
of processing (assuming there is no compression, as you have said).

I would expect YAFFS2 to grind a bit if you're writing to a partition that has 
just had a lot of files deleted. Since YAFFS2 defers the garbage collection 
until subsequent writes, this impacts on write speed. However that effect 
should not last long.


>
> 512b page NAND flash
> ====================
>
>                         Write big file  Write folder    Mount
> ---------------------+---------------------------------------
> YAFFS2, YAFFS1 mode  |  38.8 s          22.5 s          1.2 s
> JFFS2 w/o summary    |  68.6 s          16.1 s          0.7 s
> JFFS2 w/ summary     |  72.5 s          16.3 s          0.3 s