Re: simple framebuffer slower by factor of 20, on socfpga (arm) platform

On 24/04/15 16:29, Pavel Machek wrote:

Hi!

On Fri 2015-04-10 12:35:52, Archit Taneja wrote:

quoted

quoted

That said, if the fb is in RAM, and is only written by the CPU, I think
a normal memcpy() for fb_memcpy_fromfb() should be fine...

I didn't test for performance regressions when I posted this patch.

A look at _memcpy_fromio in arch/arm/kernel/io.c shows that readb() is used
all the time, even when the source and destination addresses are aligned for
larger reads to be possible. Other archs seem to use readl() or readq() when
they can. Maybe that makes memcpy_fromio slower than the implementation of
memcpy on arm?

Ok, can you prepare a patch for me to try? Or should we just revert
the original commit?

The old way worked fine, afaik, so maybe we can revert. But still, isn't
it more correct to use memcpy_fromio? It's (possibly) io memory we have
here.

 Tomi