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Date: Fri, 27 May 2011 10:14:46 +0900 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> To: Ying Han <yinghan@...gle.com> Cc: "linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>, "nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>, "balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com> Subject: Re: [RFC][PATCH v3 10/10] memcg : reclaim statistics On Thu, 26 May 2011 18:17:04 -0700 Ying Han <yinghan@...gle.com> wrote: > Hi Kame: > > I applied the patch on top of mmotm-2011-05-12-15-52. After boot up, i > keep getting the following crash by reading the > /dev/cgroup/memory/memory.reclaim_stat > > [ 200.776366] Kernel panic - not syncing: Fatal exception > [ 200.781591] Pid: 7535, comm: cat Tainted: G D W 2.6.39-mcg-DEV #130 > [ 200.788463] Call Trace: > [ 200.790916] [<ffffffff81405a75>] panic+0x91/0x194 > [ 200.797096] [<ffffffff81408ac8>] oops_end+0xae/0xbe > [ 200.803450] [<ffffffff810398d3>] die+0x5a/0x63 > [ 200.809366] [<ffffffff81408561>] do_trap+0x121/0x130 > [ 200.814427] [<ffffffff81037fe6>] do_divide_error+0x90/0x99 > [#1] SMP > [ 200.821395] [<ffffffff81112bcb>] ? mem_cgroup_reclaim_stat_read+0x28/0xf0 > [ 200.829624] [<ffffffff81104509>] ? page_add_new_anon_rmap+0x7e/0x90 > [ 200.837372] [<ffffffff810fb7f8>] ? handle_pte_fault+0x28a/0x775 > [ 200.844773] [<ffffffff8140f0f5>] divide_error+0x15/0x20 > [ 200.851471] [<ffffffff81112bcb>] ? mem_cgroup_reclaim_stat_read+0x28/0xf0 > [ 200.859729] [<ffffffff810a4a01>] cgroup_seqfile_show+0x38/0x46 > [ 200.867036] [<ffffffff810a4d72>] ? cgroup_lock+0x17/0x17 > [ 200.872444] [<ffffffff81133f2c>] seq_read+0x182/0x361 > [ 200.878984] [<ffffffff8111a0c4>] vfs_read+0xab/0x107 > [ 200.885403] [<ffffffff8111a1e0>] sys_read+0x4a/0x6e > [ 200.891764] [<ffffffff8140f469>] sysenter_dispatch+0x7/0x27 > > I will debug it, but like to post here in case i missed some patches in between. > It must be mem->scanned is 0 and mem->reclaimed * 100 /mem->scanned cause error. It must be mem->reclaimed * 100 / (mem->scanned +1). I'll fix. thank you for reporting. Thanks, -Kame > --Ying > > On Wed, May 25, 2011 at 10:36 PM, KAMEZAWA Hiroyuki > <kamezawa.hiroyu@...fujitsu.com> wrote: > > > > This patch adds a file memory.reclaim_stat. > > > > This file shows following. > > == > > recent_scan_success_ratio 12 # recent reclaim/scan ratio. > > limit_scan_pages 671 # scan caused by hitting limit. > > limit_freed_pages 538 # freed pages by limit_scan > > limit_elapsed_ns 518555076 # elapsed time in LRU scanning by limit. > > soft_scan_pages 0 # scan caused by softlimit. > > soft_freed_pages 0 # freed pages by soft_scan. > > soft_elapsed_ns 0 # elapsed time in LRU scanning by softlimit. > > margin_scan_pages 16744221 # scan caused by auto-keep-margin > > margin_freed_pages 565943 # freed pages by auto-keep-margin. > > margin_elapsed_ns 5545388791 # elapsed time in LRU scanning by auto-keep-margin > > > > This patch adds a new file rather than adding more stats to memory.stat. By it, > > this support "reset" accounting by > > > > # echo 0 > .../memory.reclaim_stat > > > > This is good for debug and tuning. > > > > TODO: > > - add Documentaion. > > > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> > > --- > > mm/memcontrol.c | 87 ++++++++++++++++++++++++++++++++++++++++++++++++++------ > > 1 file changed, 79 insertions(+), 8 deletions(-) > > > > Index: memcg_async/mm/memcontrol.c > > =================================================================== > > --- memcg_async.orig/mm/memcontrol.c > > +++ memcg_async/mm/memcontrol.c > > @@ -216,6 +216,13 @@ static void mem_cgroup_update_margin_to_ > > static void mem_cgroup_may_async_reclaim(struct mem_cgroup *mem); > > static void mem_cgroup_reflesh_scan_ratio(struct mem_cgroup *mem); > > > > +enum scan_type { > > + LIMIT_SCAN, /* scan memory because memcg hits limit */ > > + SOFT_SCAN, /* scan memory because of soft limit */ > > + MARGIN_SCAN, /* scan memory for making margin to limit */ > > + NR_SCAN_TYPES, > > +}; > > + > > /* > > * The memory controller data structure. The memory controller controls both > > * page cache and RSS per cgroup. We would eventually like to provide > > @@ -300,6 +307,13 @@ struct mem_cgroup { > > unsigned long scanned; > > unsigned long reclaimed; > > unsigned long next_scanratio_update; > > + /* For statistics */ > > + struct { > > + unsigned long nr_scanned_pages; > > + unsigned long nr_reclaimed_pages; > > + unsigned long elapsed_ns; > > + } scan_stat[NR_SCAN_TYPES]; > > + > > /* > > * percpu counter. > > */ > > @@ -1426,7 +1440,9 @@ unsigned int mem_cgroup_swappiness(struc > > > > static void __mem_cgroup_update_scan_ratio(struct mem_cgroup *mem, > > unsigned long scanned, > > - unsigned long reclaimed) > > + unsigned long reclaimed, > > + unsigned long elapsed, > > + enum scan_type type) > > { > > unsigned long limit; > > > > @@ -1439,6 +1455,9 @@ static void __mem_cgroup_update_scan_rat > > mem->scanned /= 2; > > mem->reclaimed /= 2; > > } > > + mem->scan_stat[type].nr_scanned_pages += scanned; > > + mem->scan_stat[type].nr_reclaimed_pages += reclaimed; > > + mem->scan_stat[type].elapsed_ns += elapsed; > > spin_unlock(&mem->scan_stat_lock); > > } > > > > @@ -1448,6 +1467,8 @@ static void __mem_cgroup_update_scan_rat > > * @root : root memcg of hierarchy walk. > > * @scanned : scanned pages > > * @reclaimed: reclaimed pages. > > + * @elapsed: used time for memory reclaim > > + * @type : scan type as LIMIT_SCAN, SOFT_SCAN, MARGIN_SCAN. > > * > > * record scan/reclaim ratio to the memcg both to a child and it's root > > * mem cgroup, which is a reclaim target. This value is used for > > @@ -1457,11 +1478,14 @@ static void __mem_cgroup_update_scan_rat > > static void mem_cgroup_update_scan_ratio(struct mem_cgroup *mem, > > struct mem_cgroup *root, > > unsigned long scanned, > > - unsigned long reclaimed) > > + unsigned long reclaimed, > > + unsigned long elapsed, > > + int type) > > { > > - __mem_cgroup_update_scan_ratio(mem, scanned, reclaimed); > > + __mem_cgroup_update_scan_ratio(mem, scanned, reclaimed, elapsed, type); > > if (mem != root) > > - __mem_cgroup_update_scan_ratio(root, scanned, reclaimed); > > + __mem_cgroup_update_scan_ratio(root, scanned, reclaimed, > > + elapsed, type); > > > > } > > > > @@ -1906,6 +1930,7 @@ static int mem_cgroup_hierarchical_recla > > bool is_kswapd = false; > > unsigned long excess; > > unsigned long nr_scanned; > > + unsigned long start, end, elapsed; > > > > excess = res_counter_soft_limit_excess(&root_mem->res) >> PAGE_SHIFT; > > > > @@ -1947,18 +1972,24 @@ static int mem_cgroup_hierarchical_recla > > } > > /* we use swappiness of local cgroup */ > > if (check_soft) { > > + start = sched_clock(); > > ret = mem_cgroup_shrink_node_zone(victim, gfp_mask, > > noswap, zone, &nr_scanned); > > + end = sched_clock(); > > + elapsed = end - start; > > *total_scanned += nr_scanned; > > mem_cgroup_soft_steal(victim, is_kswapd, ret); > > mem_cgroup_soft_scan(victim, is_kswapd, nr_scanned); > > mem_cgroup_update_scan_ratio(victim, > > - root_mem, nr_scanned, ret); > > + root_mem, nr_scanned, ret, elapsed, SOFT_SCAN); > > } else { > > + start = sched_clock(); > > ret = try_to_free_mem_cgroup_pages(victim, gfp_mask, > > noswap, &nr_scanned); > > + end = sched_clock(); > > + elapsed = end - start; > > mem_cgroup_update_scan_ratio(victim, > > - root_mem, nr_scanned, ret); > > + root_mem, nr_scanned, ret, elapsed, LIMIT_SCAN); > > } > > css_put(&victim->css); > > /* > > @@ -4003,7 +4034,7 @@ static void mem_cgroup_async_shrink_work > > struct delayed_work *dw = to_delayed_work(work); > > struct mem_cgroup *mem, *victim; > > long nr_to_reclaim; > > - unsigned long nr_scanned, nr_reclaimed; > > + unsigned long nr_scanned, nr_reclaimed, start, end; > > int delay = 0; > > > > mem = container_of(dw, struct mem_cgroup, async_work); > > @@ -4022,9 +4053,12 @@ static void mem_cgroup_async_shrink_work > > if (!victim) > > goto finish_scan; > > > > + start = sched_clock(); > > nr_reclaimed = mem_cgroup_shrink_rate_limited(victim, nr_to_reclaim, > > &nr_scanned); > > - mem_cgroup_update_scan_ratio(victim, mem, nr_scanned, nr_reclaimed); > > + end = sched_clock(); > > + mem_cgroup_update_scan_ratio(victim, mem, nr_scanned, nr_reclaimed, > > + end - start, MARGIN_SCAN); > > css_put(&victim->css); > > > > /* If margin is enough big, stop */ > > @@ -4680,6 +4714,38 @@ static int mem_control_stat_show(struct > > return 0; > > } > > > > +static int mem_cgroup_reclaim_stat_read(struct cgroup *cont, struct cftype *cft, > > + struct cgroup_map_cb *cb) > > +{ > > + struct mem_cgroup *mem = mem_cgroup_from_cont(cont); > > + u64 val; > > + int i; /* for indexing scan_stat[] */ > > + > > + val = mem->reclaimed * 100 / mem->scanned; > > + cb->fill(cb, "recent_scan_success_ratio", val); > > + i = LIMIT_SCAN; > > + cb->fill(cb, "limit_scan_pages", mem->scan_stat[i].nr_scanned_pages); > > + cb->fill(cb, "limit_freed_pages", mem->scan_stat[i].nr_reclaimed_pages); > > + cb->fill(cb, "limit_elapsed_ns", mem->scan_stat[i].elapsed_ns); > > + i = SOFT_SCAN; > > + cb->fill(cb, "soft_scan_pages", mem->scan_stat[i].nr_scanned_pages); > > + cb->fill(cb, "soft_freed_pages", mem->scan_stat[i].nr_reclaimed_pages); > > + cb->fill(cb, "soft_elapsed_ns", mem->scan_stat[i].elapsed_ns); > > + i = MARGIN_SCAN; > > + cb->fill(cb, "margin_scan_pages", mem->scan_stat[i].nr_scanned_pages); > > + cb->fill(cb, "margin_freed_pages", mem->scan_stat[i].nr_reclaimed_pages); > > + cb->fill(cb, "margin_elapsed_ns", mem->scan_stat[i].elapsed_ns); > > + return 0; > > +} > > + > > +static int mem_cgroup_reclaim_stat_reset(struct cgroup *cgrp, unsigned int event) > > +{ > > + struct mem_cgroup *mem = mem_cgroup_from_cont(cgrp); > > + memset(mem->scan_stat, 0, sizeof(mem->scan_stat)); > > + return 0; > > +} > > + > > + > > /* > > * User flags for async_control is a subset of mem->async_flags. But > > * this needs to be defined independently to hide implemation details. > > @@ -5163,6 +5229,11 @@ static struct cftype mem_cgroup_files[] > > .open = mem_control_numa_stat_open, > > }, > > #endif > > + { > > + .name = "reclaim_stat", > > + .read_map = mem_cgroup_reclaim_stat_read, > > + .trigger = mem_cgroup_reclaim_stat_reset, > > + } > > }; > > > > #ifdef CONFIG_CGROUP_MEM_RES_CTLR_SWAP > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.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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