[Yaffs] How to calculate the exact ram usage of YAFFS(2)?

[Sven Höhne]

Hi!

I am curerntly doing some research on YAFFS(2) and would like to 
calculate the exact RAM usage.
I already found some older threads related to this topic where it was 
only mentioned that the file trees will need the most RAM. The value 
given was approx. 2 byte of RAM per "chunk" of NAND.
My question on this value is: How was it calculated? If I use many small 
files, I will end up with a worse value per chunk and this calculation 
seems to forget about the space needed for yaffs_Objects...

For my paper I do need some more information and better values to 
calculate the RAM usage.
I would like to set up a kind of formula which would allow to calculate 
the RAM usage based on three parameters: NAND size, chunk size and the 
number of files. The calculation shall presuppose, that all space in 
NAND ist used by the given number of files, all of the same size.

I basically came up with this kind of calculation:

RAM usage = number of files * (Space for yaffs_Object + Space for tnode 
structure) + Space always needed (yaffs_Device, program in RAM, etc.)

For this, I would like to calculate the number of tnodes used for a 
given file size and would need some more info on the size of the 
strucures. I do now calculate with a yaffs_Object being 128 byte and a 
yaffs_Device being 3,5 kByte.

Thanks in advance,
Abyssina
SvH
-- 
Bernhard Muenzer in d.s.r.m. zum Thema:
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Wenn alles von Ralph Siegel erst einmal gruendlich von der CD entfernt
worden ist, gibt es auch keinen Grund mehr, sie zurueckgeben zu wollen.