On Mon, 2011-10-10 at 11:16 +0200, Eli Cohen wrote: > Until then I think we need to have the logic working right on ppc and > measure if blue flame buys us any improvement in ppc. If that's not > the case (e.g because write combining is not working), then maybe we > should avoid using blueflame in ppc. > Could any of the guys from IBM check this and give us feedback?
I don't have the necessary hardware myself to test that but maybe Thadeu can. Note that for WC to work, things must be mapped non-guarded. You can do that by using ioremap_prot() with pgprot_noncached_wc(PAGE_KERNEL) or ioremap_wc() (dunno how "generic" the later is). >From there, you should get write combining provided that you don't have barriers between every access (ie those copy operations in their current form should do the trick). Cheers, Ben. > > Maybe it's time for us to revive those discussions about providing a > > good set of relaxed MMIO accessors with explicit barriers :-) > > > > Cheers, > > Ben. > > _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev