On Thu, 2014-01-30 at 12:20 +0000, Moese, Michael wrote: > Hello PPC-developers, > I'm currently trying to benchmark access speeds to our PCIe-connected IP-cores > located inside our FPGA. On x86-based systems I was able to achieve bursts for > both read and write access. On PPC32, using an e500v2, I had no success at > all > so far. > I tried using ioremap_wc(), like I did on x86, for writing, and it only > results in my > writes just being single requests, one after another.
Hrm, ioremap_wc will give you a mapping without the G (guard) bit. Whether that results in some store gathering or not on IOs depends on a specific HW implementation, you'll have to check with the FSP folks on that one, there could also be a chicken switch (HID bit or similar) needed to enable that (there was on some earlier ppc32 chips). Another thing you can try is to use FP register load/stores. > For reads, I noticed I could not ioremap_cache() on PPC, so I used simple > ioremap() > here. > I used several ways to read from the device, from simple > readl(),memcpy_from_io(), > memcpy() to cacheable_memcpy() - with no improvements. Even when just > issuing > a batch of prefetch()-calls for all the memory to read did not result in read > bursts. > > I only get really poor results, writing is possible with around 40 MiByte/s, > whereas I > can read at about only 3 MiByte/s. > After hours of studying the reference manual from freescale, looking into > other code > and searching the web, I'm close to resignation. > > Maybe someone of you has some more directions for me, I'd appreciate every > hint > that leads me to my problem's solution - maybe I just missed something or > lack > knowledge about this architecture in general. > > Thanks for your reading. > > > Michael > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
