flash read performance

[Josh Boyer]

On Tue, Oct 28, 2008 at 11:14:05AM +0100, Andre Puschmann wrote:
>Hi list,
>
>I am currently trying to improve the flash read performance of my 
>platform. It's a gumstix verdex board with a pxa270 running at 400MHz. 
>My flash is a 16MB NOR Intel StrataFlash P30 (128P30T) and it's 
>operating in the _normal_ asynchronous mode. In my opinion the read 
>performance is very poor, only around 1.2 to 1.4 MB/s depending on the 
>blocksize. I think it should be possible to get much higher transfer rates.

Why do you think that?

>In Linux, I ran my tests with dd like this (copy 10MB):
>time dd if=/dev/mtd5 of=/dev/null bs=16k count=640
>640+0 records in
>640+0 records out
>real    0m 7.17s
>user    0m 0.00s
>sys     0m 7.17s
>
>
>Running top in another console brings up, that the CPU load is very high
>during copy. I am not sure if the system is doing some sort of busy 
>waiting or something like that? However, it should be possible to do a 
>copy without having such a high load.

Why do you think that?  The chip drivers don't do DMA, so all I/O goes
through the CPU.

josh