On Wednesday, March 23, 2005 10:24 pm, Benjamin Herrenschmidt wrote: > While experimenting with framebuffer access performances, we noticed a > very significant improvement in write access to it when not setting > the "guarded" bit on the MMU mappings. This bit basically says that > reads and writes won't have side effects (it allows speculation). It > appears that it also disables write combining.
Doesn't pgprot_writecombine imply non-guarded, so can't you use it instead? Either way, you'll probably want to fix fbmem.c as well and turn off _PAGE_GUARDED? Maybe it's time for a more generic call to support this stuff, both for in-kernel mappings and ones that we export to userspace. Jesse - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/