On Sun, 2010-03-07 at 09:07 +0530, James Bottomley wrote: > So, assuming full congruence of user space, can't you use the VMA as an > indicator? i.e. if we have no user space mappings, we have to flush the > icache ... if we have one or more, the icache has been flushed and > placing the same page congruently in a different address space benefits > from that prior flush, so consequently there's no need to flush again? the VMA ? Or you mean struct page -> mapping ? That would work I suppose in the case where we want to flush the icache pages for all pages mapped into user space. But on processors that support per-page execute permission, we really only want to flush pages that are executed from (lazily). In that case, we do need a dedicated bit to keep track of whether a given page has been flushed already. > I also think we've established the relevant facts for the I/O thread > (that we only need to either flush the kernel D cache or mark it as to > be flushed later on PIO reads). We're now into deep technicalities of > how the mm system operates at the architecture level, so perhaps we > should move this to linux-arch? No objection though moving threads after the fact is a recipe for trouble :-) Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
