Re: [PATCH 1/5] pagewalk: only split huge pages when necessary
From: David Rientjes <rientjes@google.com>
Date: 2011-02-22 21:21:58
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On Mon, 21 Feb 2011, Dave Hansen wrote:
v2 - rework if() block, and remove now redundant split_huge_page() Right now, if a mm_walk has either ->pte_entry or ->pmd_entry set, it will unconditionally split any transparent huge pages it runs in to. In practice, that means that anyone doing a cat /proc/$pid/smaps will unconditionally break down every huge page in the process and depend on khugepaged to re-collapse it later. This is fairly suboptimal. This patch changes that behavior. It teaches each ->pmd_entry handler (there are five) that they must break down the THPs themselves. Also, the _generic_ code will never break down a THP unless a ->pte_entry handler is actually set. This means that the ->pmd_entry handlers can now choose to deal with THPs without breaking them down. Acked-by: Mel Gorman <redacted> Signed-off-by: Dave Hansen <redacted>
Acked-by: David Rientjes <rientjes@google.com> Thanks for adding the comment about ->pmd_entry() being required to split the pages in include/linux/mm.h! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>