On Sat, Dec 24, 2011 at 4:45 AM, Dave Chinner <david@xxxxxxxxxxxxx> wrote: [...] > > Ok, it's not a shrink_slab() problem - it's just being called ~100uS > by kswapd. The pattern is: > > - reclaim 94 (batches of 32,32,30) pages from iinactive list > of zone 1, node 0, prio 12 > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > - 40us gap > - reclaim 10-30 pages from inactive list of zone 2, node 0, prio 12 > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > - 40us gap > - isolate 9 pages from LRU zone ?, node ?, none isolated, none freed > - isolate 22 pages from LRU zone ?, node ?, none isolated, none freed > - call shrink_slab > - scan all caches > - all shrinkers return 0 saying nothing to shrink > 40us gap > > And it just repeats over and over again. After a while, nid=0,zone=1 > drops out of the traces, so reclaim only comes in batches of 10-30 > pages from zone 2 between each shrink_slab() call. > > The trace starts at 111209.881s, with 944776 pages on the LRUs. It > finishes at 111216.1 with kswapd going to sleep on node 0 with > 930067 pages on the LRU. So 7 seconds to free 15,000 pages (call it > 2,000 pages/s) which is awfully slow.... > Hi all, In hope, the added debug info is helpful. Hillf --- --- a/mm/memcontrol.c Fri Dec 9 21:57:40 2011 +++ b/mm/memcontrol.c Sun Dec 25 17:08:14 2011 @@ -1038,7 +1038,11 @@ void mem_cgroup_lru_del_list(struct page memcg = root_mem_cgroup; mz = page_cgroup_zoneinfo(memcg, page); /* huge page split is done under lru_lock. so, we have no races. */ - MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page); + if (WARN_ON_ONCE(MEM_CGROUP_ZSTAT(mz, lru) < + (1 << compound_order(page)))) + MEM_CGROUP_ZSTAT(mz, lru) = 0; + else + MEM_CGROUP_ZSTAT(mz, lru) -= 1 << compound_order(page); } void mem_cgroup_lru_del(struct page *page) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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