Messages in this thread | | | Date | Fri, 28 Aug 2009 13:53:42 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [RFC][PATCH 2/5] memcg: uncharge in batched manner |
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On Fri, 28 Aug 2009 13:24:38 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > In massive parallel enviroment, res_counter can be a performance bottleneck. > This patch is a trial for reducing lock contention. > One strong techinque to reduce lock contention is reducing calls by > batching some amount of calls int one. > > Considering charge/uncharge chatacteristic, > - charge is done one by one via demand-paging. > - uncharge is done by > - in chunk at munmap, truncate, exit, execve... > - one by one via vmscan/paging. > > It seems we hace a chance to batched-uncharge. > This patch is a base patch for batched uncharge. For avoiding > scattering memcg's structure, this patch adds memcg batch uncharge > information to the task. please see start/end usage in next patch. > > Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> > --- > include/linux/memcontrol.h | 12 +++++++ > include/linux/sched.h | 7 ++++ > mm/memcontrol.c | 70 +++++++++++++++++++++++++++++++++++++++++---- > 3 files changed, 83 insertions(+), 6 deletions(-) > > Index: mmotm-2.6.31-Aug27/include/linux/memcontrol.h > =================================================================== > --- mmotm-2.6.31-Aug27.orig/include/linux/memcontrol.h > +++ mmotm-2.6.31-Aug27/include/linux/memcontrol.h > @@ -54,6 +54,10 @@ extern void mem_cgroup_rotate_lru_list(s > extern void mem_cgroup_del_lru(struct page *page); > extern void mem_cgroup_move_lists(struct page *page, > enum lru_list from, enum lru_list to); > + > +extern void mem_cgroup_uncharge_batch_start(void); > +extern void mem_cgroup_uncharge_batch_end(void); > + > extern void mem_cgroup_uncharge_page(struct page *page); > extern void mem_cgroup_uncharge_cache_page(struct page *page); > extern int mem_cgroup_shmem_charge_fallback(struct page *page, > @@ -151,6 +155,14 @@ static inline void mem_cgroup_cancel_cha > { > } > > +static inline void mem_cgroup_uncharge_batch_start(void) > +{ > +} > + > +static inline void mem_cgroup_uncharge_batch_start(void) > +{ > +} > + > static inline void mem_cgroup_uncharge_page(struct page *page) > { > } > Index: mmotm-2.6.31-Aug27/mm/memcontrol.c > =================================================================== > --- mmotm-2.6.31-Aug27.orig/mm/memcontrol.c > +++ mmotm-2.6.31-Aug27/mm/memcontrol.c > @@ -1837,7 +1837,35 @@ void mem_cgroup_cancel_charge_swapin(str > css_put(&mem->css); > } > > +static bool > +__do_batch_uncharge(struct mem_cgroup *mem, const enum charge_type ctype) > +{ > + struct memcg_batch_info *batch = NULL; > + bool uncharge_memsw; > + /* If swapout, usage of swap doesn't decrease */ > + if (do_swap_account && (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT)) > + uncharge_memsw = false; > + else > + uncharge_memsw = true; > > + if (current->memcg_batch.do_batch) { > + batch = ¤t->memcg_batch; > + if (batch->memcg == NULL) { > + batch->memcg = mem; > + css_get(&mem->css); > + } > + } > + if (!batch || batch->memcg != mem) { > + res_counter_uncharge(&mem->res, PAGE_SIZE); > + if (uncharge_memsw) > + res_counter_uncharge(&mem->memsw, PAGE_SIZE); > + } else { > + batch->pages += PAGE_SIZE; > + if (uncharge_memsw) > + batch->memsw += PAGE_SIZE; > + } > + return soft_limit_excess; > +} > /* > * uncharge if !page_mapped(page) > */ > @@ -1886,12 +1914,8 @@ __mem_cgroup_uncharge_common(struct page > break; > } > > - if (!mem_cgroup_is_root(mem)) { > - res_counter_uncharge(&mem->res, PAGE_SIZE); > - if (do_swap_account && > - (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)) > - res_counter_uncharge(&mem->memsw, PAGE_SIZE); > - } > + if (!mem_cgroup_is_root(mem)) > + __do_batch_uncharge(mem, ctype); > if (ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) > mem_cgroup_swap_statistics(mem, true); > mem_cgroup_charge_statistics(mem, pc, false); > @@ -1938,6 +1962,40 @@ void mem_cgroup_uncharge_cache_page(stru > __mem_cgroup_uncharge_common(page, MEM_CGROUP_CHARGE_TYPE_CACHE); > } > > +void mem_cgroup_uncharge_batch_start(void) > +{ > + VM_BUG_ON(current->memcg_batch.do_batch); > + /* avoid batch if killed by OOM */ > + if (test_thread_flag(TIF_MEMDIE)) > + return; > + current->memcg_batch.do_batch = 1; > + current->memcg_batch.memcg = NULL; > + current->memcg_batch.pages = 0; > + current->memcg_batch.memsw = 0; > +} > + > +void mem_cgroup_uncharge_batch_end(void) > +{ > + struct mem_cgroup *mem; > + > + if (!current->memcg_batch.do_batch) > + return; > + > + current->memcg_batch.do_batch = 0; > + > + mem = current->memcg_batch.memcg; > + if (!mem) > + return; > + if (current->memcg_batch.pages) > + res_counter_uncharge(&mem->res, > + current->memcg_batch.pages, NULL); > + if (current->memcg_batch.memsw) > + res_counter_uncharge(&mem->memsw, > + current->memcg_batch.memsw, NULL);
quilt refresh miss....above 2 NULL are unnecesary.
sorry, -Kame
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