Hi Stefan, On Thu, Nov 12, 2015 at 12:20 AM, Stefan Monnier <[email protected]> wrote: >> When the CPU clock speed is set to 480 MHz by the U-Boot SPL, > ^^^ > You mean MBUS? > >> the performance improvement for 'sunxi-fel write' transfers >> to DRAM is ~95 KB/s -> ~510 KB/s. > >> When the CPU clock speed is set to 1008 MHz by the U-Boot SPL, >> the performance improvement for 'sunxi-fel write' transfers >> to DRAM is ~180 KB/s -> ~510 KB/s. > > I don't understand the relation between the above 2 improvements. > What change causes the speed to go from 95KB/s to 180KB/s?
My interpretation of this was that before this change, the transfer speed was somehow limited by the clock speed. With the MMU enabled, it appears that the clock speed is no-longer the limiting factor. (I'm _guessing_ that the transfer has to bounce through the CPU and this was slow without the MMU for some reason. I'm also guessing that enabling the MMU has moved the bottleneck elsewhere - possibly the USB hardware.) Thanks, -- Julian Calaby Email: [email protected] Profile: http://www.google.com/profiles/julian.calaby/ -- You received this message because you are subscribed to the Google Groups "linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
