Messages in this thread | | | Date | Thu, 23 Jun 2011 23:10:11 +0900 | Subject | Re: [PATCH 7/7] memcg: proportional fair vicitm node selection | From | Hiroyuki Kamezawa <> |
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2011/6/23 Michal Hocko <mhocko@suse.cz>: > On Thu 16-06-11 12:57:41, KAMEZAWA Hiroyuki wrote: >> From 4fbd49697456c227c86f1d5b46f2cd2169bf1c5b Mon Sep 17 00:00:00 2001 >> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> >> Date: Thu, 16 Jun 2011 11:25:23 +0900 >> Subject: [PATCH 7/7] memcg: proportional fair node vicitm selection >> >> commit 889976 implements a round-robin scan of numa nodes for >> LRU scanning of memcg at hitting limit. >> But, round-robin is not very good. >> >> This patch implements a proportionally fair victim selection of nodes >> rather than round-robin. The logic is fair against each node's weight. >> >> Each node's weight is calculated periodically and we build an node's >> scheduling entity as >> >> total_ticket = 0; >> for_each_node(node) >> node->ticket_start = total_ticket; >> node->ticket_end = total_ticket + this_node's_weight() >> total_ticket = node->ticket_end; >> >> Then, each nodes has some amounts of tickets in proportion to its own weight. >> >> At selecting victim, a random number is selected and the node which contains >> the random number in [ticket_start, ticket_end) is selected as vicitm. >> This is a lottery scheduling algorithm. >> >> For quick search of victim, this patch uses bsearch(). >> >> Test result: >> on 8cpu box with 2 nodes. >> limit memory to be 300MB and run httpd for 4096files/600MB working set. >> do (normalized) random access by apache-bench and see scan_stat. >> The test makes 40960 request. and see scan_stat. >> (Because a httpd thread just use 10% cpu, the number of threads will >> not be balanced between nodes. Then, file caches will not be balanced >> between nodes.) > > Have you also tried to test with balanced nodes? I mean, is there any > measurable overhead? >
Not enough yet. I checked OOM trouble this week :).
I may need to make another fake_numa setup + cpuset to measurements. In usual path, new overhead is random32() and bsearch(). I'll do some.
Thanks, -Kame -- 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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