Re: [PATCH 2/2] mtd: orion-nand: fix build error with ARMv4

Arnd Bergmann
2014-05-09T22:24:02Z

On Friday 09 May 2014 19:09:15 Ezequiel Garcia wrote:
> # time nanddump /dev/mtd5 -f /dev/null -q
> real 0m 5.82s
> user 0m 0.20s
> sys 0m 5.60s
>
> Jason: Care to submit a proper patch?
>
> On 08 May 04:56 PM, Arnd Bergmann wrote:
> > Ok, that is a noticeable difference. For scale, what is the size of that partition?
>
> The board is Openblocks A6, running mainline.
>
> # cat /proc/mtd
> dev: size erasesize name
> mtd0: 00090000 00004000 "uboot"
> mtd1: 00044000 00004000 "env"
> mtd2: 00024000 00004000 "test"
> mtd3: 00400000 00004000 "conf"
> mtd4: 01d20000 00004000 "linux"
> mtd5: 01dec000 00004000 "user"

Ok, so it takes 5.6 seconds in kernel mode to access 31MB, which comes down
to 5.60MB/s. That isn't very fast compared to the time the CPU should take
for those instructions, so I'm surprised it actually makes any difference
at all.

There isn't a usable slave DMA engine in Armada XP by chance?

Arnd