Messages in this thread | | | Date | Sat, 19 Mar 2005 16:27:29 -0800 | From | "David S. Miller" <> | Subject | Re: [patch] arch hook for notifying changes in PTE protections bits |
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On Sat, 19 Mar 2005 12:30:05 -0800 David Mosberger <davidm@napali.hpl.hp.com> wrote:
> I agree about your concern about cost. Accessing the page_map is > expensive (integer division + memory access) and we have to do that in > order to find out if the page is i-cache clean.
First, it's a multiply by reciprocol. At least on sparc64 I get this emitted by the compiler.
Secondly, if you're willing to sacrifice 8 bytes per page struct simply define WANT_PAGE_VIRTUAL and page struct will be exactly 64 bytes and thus the divide a will turn into a simple shift. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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