[ECOS] Huge performance difference between read() and fread()

Rutger Hofman rutger@cs.vu.nl
Wed Jan 9 15:13:00 GMT 2008

Hi list,

I have a board with an PXA270 and 32MB of flash, part of which is 
configured as a jffs2 flash file system with Flash/v2 and legacy 
interface. I also have language/C and many other C components configured 
in, the relevant functions are open()/read() and fopen()/fread().

Now, if I read a file of size 503549 on this jffs2 file system, the 
performance is *wildly* different for read() and fread():

file "/fpga/guardian_v3_rev_b.svf" size 503549
read file /fpga/guardian_v3_rev_b.svf size 503549 takes 0.863116
fread file /fpga/guardian_v3_rev_b.svf size 503549 takes 16.601978

Times are in seconds.

Question: why are the timings a factor of 20 apart? Why are the timings 
different at all? I'd think that both do more or less exactly the same 
thing, although at a different interface.

Rutger Hofman
VU Amsterdam

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