From: Dave Hansen <dave@linux.vnet.ibm.com> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Michael J Wolf <mjwolf@us.ibm.com>, Andrea Arcangeli <aarcange@redhat.com>, Dave Hansen <dave@linux.vnet.ibm.com> Subject: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages Date: Wed, 09 Feb 2011 11:54:06 -0800 [thread overview] Message-ID: <20110209195406.B9F23C9F@kernel> (raw) Andrea, after playing with this for a week or two, I'm quite a bit more confident that it's not causing much harm. Seems a fairly low-risk feature. Could we stick these somewhere so they'll at least hit linux-next for the 2.6.40 cycle perhaps? -- I'm working on some more reports that transparent huge pages and KSM do not play nicely together. Basically, whenever THP's are present along with KSM, there is a lot of attrition over time, and we do not see much overall progress keeping THP's around: http://sr71.net/~dave/ibm/038_System_Anonymous_Pages.png (That's Karl Rister's graph, thanks Karl!) However, I realized that we do not currently have a nice way to find out where individual THP's might be on the system. We have an overall count, but no way of telling which processes or VMAs they might be in. I started to implement this in the /proc/$pid/smaps code, but quickly realized that the lib/pagewalk.c code unconditionally splits THPs up. This set reworks that code a bit and, in the end, gives you a per-map count of the numbers of huge pages. It also makes it possible for page walks to _not_ split THPs.
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From: Dave Hansen <dave@linux.vnet.ibm.com> To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, Michael J Wolf <mjwolf@us.ibm.com>, Andrea Arcangeli <aarcange@redhat.com>, Dave Hansen <dave@linux.vnet.ibm.com> Subject: [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages Date: Wed, 09 Feb 2011 11:54:06 -0800 [thread overview] Message-ID: <20110209195406.B9F23C9F@kernel> (raw) Andrea, after playing with this for a week or two, I'm quite a bit more confident that it's not causing much harm. Seems a fairly low-risk feature. Could we stick these somewhere so they'll at least hit linux-next for the 2.6.40 cycle perhaps? -- I'm working on some more reports that transparent huge pages and KSM do not play nicely together. Basically, whenever THP's are present along with KSM, there is a lot of attrition over time, and we do not see much overall progress keeping THP's around: http://sr71.net/~dave/ibm/038_System_Anonymous_Pages.png (That's Karl Rister's graph, thanks Karl!) However, I realized that we do not currently have a nice way to find out where individual THP's might be on the system. We have an overall count, but no way of telling which processes or VMAs they might be in. I started to implement this in the /proc/$pid/smaps code, but quickly realized that the lib/pagewalk.c code unconditionally splits THPs up. This set reworks that code a bit and, in the end, gives you a per-map count of the numbers of huge pages. It also makes it possible for page walks to _not_ split THPs. -- 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>
next reply other threads:[~2011-02-09 19:54 UTC|newest] Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top 2011-02-09 19:54 Dave Hansen [this message] 2011-02-09 19:54 ` [PATCH 0/5] fix up /proc/$pid/smaps to not split huge pages Dave Hansen 2011-02-09 19:54 ` [PATCH 1/5] pagewalk: only split huge pages when necessary Dave Hansen 2011-02-09 19:54 ` Dave Hansen 2011-02-10 11:11 ` Mel Gorman 2011-02-10 11:11 ` Mel Gorman 2011-02-10 13:19 ` Andrea Arcangeli 2011-02-10 13:19 ` Andrea Arcangeli 2011-02-10 13:34 ` Mel Gorman 2011-02-10 13:34 ` Mel Gorman 2011-02-09 19:54 ` [PATCH 2/5] break out smaps_pte_entry() from smaps_pte_range() Dave Hansen 2011-02-09 19:54 ` Dave Hansen 2011-02-10 11:15 ` Mel Gorman 2011-02-10 11:15 ` Mel Gorman 2011-02-09 19:54 ` [PATCH 3/5] pass pte size argument in to smaps_pte_entry() Dave Hansen 2011-02-09 19:54 ` Dave Hansen 2011-02-10 11:16 ` Mel Gorman 2011-02-10 11:16 ` Mel Gorman 2011-02-09 19:54 ` [PATCH 4/5] teach smaps_pte_range() about THP pmds Dave Hansen 2011-02-09 19:54 ` Dave Hansen 2011-02-10 11:17 ` Mel Gorman 2011-02-10 11:17 ` Mel Gorman 2011-02-10 18:08 ` Andrea Arcangeli 2011-02-10 18:08 ` Andrea Arcangeli 2011-02-10 19:32 ` Dave Hansen 2011-02-10 19:32 ` Dave Hansen 2011-02-09 19:54 ` [PATCH 5/5] have smaps show transparent huge pages Dave Hansen 2011-02-09 19:54 ` Dave Hansen 2011-02-10 11:20 ` Mel Gorman 2011-02-10 11:20 ` Mel Gorman 2011-02-10 15:01 ` Dave Hansen 2011-02-10 15:01 ` Dave Hansen 2011-02-10 15:09 ` Mel Gorman 2011-02-10 15:09 ` Mel Gorman 2011-02-10 18:09 ` Andrea Arcangeli 2011-02-10 18:09 ` Andrea Arcangeli 2011-02-10 18:20 ` Dave Hansen 2011-02-10 18:20 ` Dave Hansen 2011-02-10 18:39 ` Andrea Arcangeli 2011-02-10 18:39 ` Andrea Arcangeli 2011-02-09 21:24 ` [PATCH 0/5] fix up /proc/$pid/smaps to not split " Andrea Arcangeli 2011-02-09 21:24 ` Andrea Arcangeli 2011-02-20 21:54 ` David Rientjes 2011-02-20 21:54 ` David Rientjes 2011-02-15 16:55 ` Eric B Munson 2011-02-15 17:01 ` Andrea Arcangeli 2011-02-15 17:01 ` Andrea Arcangeli 2011-02-15 17:05 ` Dave Hansen 2011-02-15 17:05 ` Dave Hansen 2011-02-15 18:00 ` Andrea Arcangeli 2011-02-15 18:00 ` Andrea Arcangeli 2011-02-22 1:53 Dave Hansen 2011-02-22 1:53 ` Dave Hansen
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