Flash writing and reading speed (was: Re: Picture viewer?)

Mike Montour mail at mmontour.net
Fri Feb 15 07:59:51 CET 2008

Asheesh Laroia wrote:

> Not to mention eight megabytes of I/O from the micro-SD slot.  I don't 
> have my Neo on-hand, but it'd be great to see some performance numbers 
> that can indicate what sort of performance is reasonable to expect.

I have written a small program that measures the speed of writing and 
reading a file. It is located at 
http://members.shaw.ca/mmontour/neo/iospeed (with a .c source file in 
the same directory) and it takes 2 parameters - the filename, and the 
desired size in MiB. Examples for my GTA01:

NAND flash, jffs2 filesystem:
root at fic-gta01:/mnt# ~/iospeed test.dat 8
Size (MiB)	Write (MiB/s)	Read (MiB/s)
8	1.503	7.113

Kingston 2G SD-card, ext3 filesystem:
root at fic-gta01:~# ~/iospeed test.dat 8
Size (MiB)	Write (MiB/s)	Read (MiB/s)
8	2.276	3.243

The write measurement includes the time to fsync() the file after 
writing all of the data, and the cache is flushed with posix_fadvise() 
before performing the read test.

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