On Mon, 19 Mar 2007 17:44:28 -0700 (PDT) Christoph Lameter <[EMAIL PROTECTED]> wrote:
> On Mon, 19 Mar 2007, Andrew Morton wrote: > > > Please provide proof that quicklists are superior to simply going direct to > > the page allocator for these pages. > > See the patch. We are only touching 2 cachelines instead of 32. So even > without considering the page allocator overhead and the slab allocator > overhead (which will make the situation even better) its superior. That's not proof, it is handwaving. I could wave right back at you and claim that the benefit from returning a cache-hot pte page back to the page allocator for reuse exceeds the benefit which you waved at me above. You may well be right, but nothing is proven, afaict. > > > I doubt it. The zeroing is a by product of our way of serializing pte > > > handling. Its going to be difficult to change that. > > > > Nick didn't think so, and I don't see the problem either. > > You do not think that our current way of handling ptes is okay? If we do > not zero the ptes then we need to separate munmap from process shutdown. Yep. It's possible that process shutdown is a sufficiently common and costly special-case for it to be worth special-casing. > > We'll save on some bus traffic by avoiding the writeback, but how much > > effect that will have we don't know. Presumably little. > > The advantage of the quicklists is that it does not require a rework of > the pte serialization. No, these are unrelated. We can get pte pages from the page allocator and zero them without touching the munmap handling. But it's possible that if we _were_ to optimise the munmap handling as suggested, the end result would be superior. - 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/
