Re: [PATCH 0/5] mm improvements

[Nick Piggin <piggin@xxxxxxxxxxxxxxx>]

Nikita Danilov wrote:

>To my surprise I have just found that
>
>ftp://ftp.namesys.com/pub/misc-patches/unsupported/extra/2004.02.04/p10-trasnfer-dirty-on-refill.patch
>
>[yes, I know there is a typo in the name.]
>
>patch improves performance quite measurably. It implements a suggestion
>made in the comment in refill_inactive_zone():
>
> 			/*
>			 * probably it would be useful to transfer dirty bit
>			 * from pte to the @page here.
> 			 */
>
>To do this page_is_dirty() function is used (the same one as used by
>dont-unmap-on-pageout.patch), which is implemented in
>check-pte-dirty.patch.
>
>I ran
>
>$ time build.sh 10 11
>
>(attached) and get following elapsed time:
>
>without patch: 3818.320, with patch: 3368.690 (11% improvement).
>
>

That looks nice. I promise I will test your new patches, but
can you tell me if I've misread this patch?

2004.02.04/p0f-check-pte-dirty.patch:
function page_is_dirty:
if not PageDirect, then for each pte:

+				pte_dirty = page_pte_is_dirty(page, pte_paddr);
+				if (pte_dirty != 0)
+					ret = pte_dirty;


Won't this leave ret in a random state? Should it be ret++?

Nick


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