From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752072Ab1FHBvA (ORCPT ); Tue, 7 Jun 2011 21:51:00 -0400 Received: from smtp-out.google.com ([216.239.44.51]:13387 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751055Ab1FHBu5 convert rfc822-to-8bit (ORCPT ); Tue, 7 Jun 2011 21:50:57 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; b=mVMIffPiMDdiUc83ymffXwbaev2A4zFUA7oyagKJ3cHyqKC/gzmgAB4jrCAStpKdDE JkO4yUTMDSWT+TIPhFew== MIME-Version: 1.0 In-Reply-To: <20110608090132.ef9ccb91.kamezawa.hiroyu@jp.fujitsu.com> References: <1307117538-14317-1-git-send-email-gthelen@google.com> <1307117538-14317-11-git-send-email-gthelen@google.com> <20110607175056.83619c5f.kamezawa.hiroyu@jp.fujitsu.com> <20110608090132.ef9ccb91.kamezawa.hiroyu@jp.fujitsu.com> From: Greg Thelen Date: Tue, 7 Jun 2011 18:50:34 -0700 Message-ID: Subject: Re: [PATCH v8 10/12] memcg: create support routines for page-writeback To: KAMEZAWA Hiroyuki Cc: Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , containers@lists.osdl.org, linux-fsdevel@vger.kernel.org, Andrea Righi , Balbir Singh , Daisuke Nishimura , Minchan Kim , Johannes Weiner , Ciju Rajan K , David Rientjes , Wu Fengguang , Vivek Goyal , Dave Chinner Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 7, 2011 at 5:01 PM, KAMEZAWA Hiroyuki wrote: > On Tue, 07 Jun 2011 08:58:16 -0700 > Greg Thelen wrote: > >> KAMEZAWA Hiroyuki writes: >> >> > On Fri,  3 Jun 2011 09:12:16 -0700 >> > Greg Thelen wrote: >> > >> >> Introduce memcg routines to assist in per-memcg dirty page management: >> >> >> >> - mem_cgroup_balance_dirty_pages() walks a memcg hierarchy comparing >> >>   dirty memory usage against memcg foreground and background thresholds. >> >>   If an over-background-threshold memcg is found, then per-memcg >> >>   background writeback is queued.  Per-memcg writeback differs from >> >>   classic, non-memcg, per bdi writeback by setting the new >> >>   writeback_control.for_cgroup bit. >> >> >> >>   If an over-foreground-threshold memcg is found, then foreground >> >>   writeout occurs.  When performing foreground writeout, first consider >> >>   inodes exclusive to the memcg.  If unable to make enough progress, >> >>   then consider inodes shared between memcg.  Such cross-memcg inode >> >>   sharing likely to be rare in situations that use per-cgroup memory >> >>   isolation.  The approach tries to handle the common (non-shared) >> >>   case well without punishing well behaved (non-sharing) cgroups. >> >>   As a last resort writeback shared inodes. >> >> >> >>   This routine is used by balance_dirty_pages() in a later change. >> >> >> >> - mem_cgroup_hierarchical_dirty_info() returns the dirty memory usage >> >>   and limits of the memcg closest to (or over) its dirty limit.  This >> >>   will be used by throttle_vm_writeout() in a latter change. >> >> >> >> Signed-off-by: Greg Thelen >> >> --- >> >> Changelog since v7: >> >> - Add more detail to commit description. >> >> >> >> - Declare the new writeback_control for_cgroup bit in this change, the >> >>   first patch that uses the new field is first used.  In -v7 the field >> >>   was declared in a separate patch. >> >> >> >>  include/linux/memcontrol.h        |   18 +++++ >> >>  include/linux/writeback.h         |    1 + >> >>  include/trace/events/memcontrol.h |   83 ++++++++++++++++++++ >> >>  mm/memcontrol.c                   |  150 +++++++++++++++++++++++++++++++++++++ >> >>  4 files changed, 252 insertions(+), 0 deletions(-) >> >> >> >> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h >> >> index 3d72e09..0d0363e 100644 >> >> --- a/include/linux/memcontrol.h >> >> +++ b/include/linux/memcontrol.h >> >> @@ -167,6 +167,11 @@ bool should_writeback_mem_cgroup_inode(struct inode *inode, >> >>                                   struct writeback_control *wbc); >> >>  bool mem_cgroups_over_bground_dirty_thresh(void); >> >>  void mem_cgroup_writeback_done(void); >> >> +bool mem_cgroup_hierarchical_dirty_info(unsigned long sys_available_mem, >> >> +                                  struct mem_cgroup *mem, >> >> +                                  struct dirty_info *info); >> >> +void mem_cgroup_balance_dirty_pages(struct address_space *mapping, >> >> +                              unsigned long write_chunk); >> >> >> >>  unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, >> >>                                            gfp_t gfp_mask, >> >> @@ -383,6 +388,19 @@ static inline void mem_cgroup_writeback_done(void) >> >>  { >> >>  } >> >> >> >> +static inline void mem_cgroup_balance_dirty_pages(struct address_space *mapping, >> >> +                                            unsigned long write_chunk) >> >> +{ >> >> +} >> >> + >> >> +static inline bool >> >> +mem_cgroup_hierarchical_dirty_info(unsigned long sys_available_mem, >> >> +                             struct mem_cgroup *mem, >> >> +                             struct dirty_info *info) >> >> +{ >> >> +  return false; >> >> +} >> >> + >> >>  static inline >> >>  unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, >> >>                                        gfp_t gfp_mask, >> >> diff --git a/include/linux/writeback.h b/include/linux/writeback.h >> >> index 66ec339..4f5c0d2 100644 >> >> --- a/include/linux/writeback.h >> >> +++ b/include/linux/writeback.h >> >> @@ -47,6 +47,7 @@ struct writeback_control { >> >>    unsigned for_reclaim:1;         /* Invoked from the page allocator */ >> >>    unsigned range_cyclic:1;        /* range_start is cyclic */ >> >>    unsigned more_io:1;             /* more io to be dispatched */ >> >> +  unsigned for_cgroup:1;          /* enable cgroup writeback */ >> >>    unsigned shared_inodes:1;       /* write inodes spanning cgroups */ >> >>  }; >> >> >> >> diff --git a/include/trace/events/memcontrol.h b/include/trace/events/memcontrol.h >> >> index 326a66b..b42dae1 100644 >> >> --- a/include/trace/events/memcontrol.h >> >> +++ b/include/trace/events/memcontrol.h >> >> @@ -109,6 +109,89 @@ TRACE_EVENT(mem_cgroups_over_bground_dirty_thresh, >> >>              __entry->first_id) >> >>  ) >> >> >> >> +DECLARE_EVENT_CLASS(mem_cgroup_consider_writeback, >> >> +  TP_PROTO(unsigned short css_id, >> >> +           struct backing_dev_info *bdi, >> >> +           unsigned long nr_reclaimable, >> >> +           unsigned long thresh, >> >> +           bool over_limit), >> >> + >> >> +  TP_ARGS(css_id, bdi, nr_reclaimable, thresh, over_limit), >> >> + >> >> +  TP_STRUCT__entry( >> >> +          __field(unsigned short, css_id) >> >> +          __field(struct backing_dev_info *, bdi) >> >> +          __field(unsigned long, nr_reclaimable) >> >> +          __field(unsigned long, thresh) >> >> +          __field(bool, over_limit) >> >> +  ), >> >> + >> >> +  TP_fast_assign( >> >> +          __entry->css_id = css_id; >> >> +          __entry->bdi = bdi; >> >> +          __entry->nr_reclaimable = nr_reclaimable; >> >> +          __entry->thresh = thresh; >> >> +          __entry->over_limit = over_limit; >> >> +  ), >> >> + >> >> +  TP_printk("css_id=%d bdi=%p nr_reclaimable=%ld thresh=%ld " >> >> +            "over_limit=%d", __entry->css_id, __entry->bdi, >> >> +            __entry->nr_reclaimable, __entry->thresh, __entry->over_limit) >> >> +) >> >> + >> >> +#define DEFINE_MEM_CGROUP_CONSIDER_WRITEBACK_EVENT(name) \ >> >> +DEFINE_EVENT(mem_cgroup_consider_writeback, name, \ >> >> +  TP_PROTO(unsigned short id, \ >> >> +           struct backing_dev_info *bdi, \ >> >> +           unsigned long nr_reclaimable, \ >> >> +           unsigned long thresh, \ >> >> +           bool over_limit), \ >> >> +  TP_ARGS(id, bdi, nr_reclaimable, thresh, over_limit) \ >> >> +) >> >> + >> >> +DEFINE_MEM_CGROUP_CONSIDER_WRITEBACK_EVENT(mem_cgroup_consider_bg_writeback); >> >> +DEFINE_MEM_CGROUP_CONSIDER_WRITEBACK_EVENT(mem_cgroup_consider_fg_writeback); >> >> + >> >> +TRACE_EVENT(mem_cgroup_fg_writeback, >> >> +  TP_PROTO(unsigned long write_chunk, >> >> +           struct writeback_control *wbc), >> >> + >> >> +  TP_ARGS(write_chunk, wbc), >> >> + >> >> +  TP_STRUCT__entry( >> >> +          __field(unsigned long, write_chunk) >> >> +          __field(long, wbc_to_write) >> >> +          __field(bool, shared_inodes) >> >> +  ), >> >> + >> >> +  TP_fast_assign( >> >> +          __entry->write_chunk = write_chunk; >> >> +          __entry->wbc_to_write = wbc->nr_to_write; >> >> +          __entry->shared_inodes = wbc->shared_inodes; >> >> +  ), >> >> + >> >> +  TP_printk("write_chunk=%ld nr_to_write=%ld shared_inodes=%d", >> >> +            __entry->write_chunk, >> >> +            __entry->wbc_to_write, >> >> +            __entry->shared_inodes) >> >> +) >> >> + >> >> +TRACE_EVENT(mem_cgroup_enable_shared_writeback, >> >> +  TP_PROTO(unsigned short css_id), >> >> + >> >> +  TP_ARGS(css_id), >> >> + >> >> +  TP_STRUCT__entry( >> >> +          __field(unsigned short, css_id) >> >> +          ), >> >> + >> >> +  TP_fast_assign( >> >> +          __entry->css_id = css_id; >> >> +          ), >> >> + >> >> +  TP_printk("enabling shared writeback for memcg %d", __entry->css_id) >> >> +) >> >> + >> >>  #endif /* _TRACE_MEMCONTROL_H */ >> >> >> >>  /* This part must be outside protection */ >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> >> index a5b1794..17cb888 100644 >> >> --- a/mm/memcontrol.c >> >> +++ b/mm/memcontrol.c >> >> @@ -1622,6 +1622,156 @@ void mem_cgroup_writeback_done(void) >> >>    } >> >>  } >> >> >> >> +/* >> >> + * This routine must be called by processes which are generating dirty pages. >> >> + * It considers the dirty pages usage and thresholds of the current cgroup and >> >> + * (depending if hierarchical accounting is enabled) ancestral memcg.  If any of >> >> + * the considered memcg are over their background dirty limit, then background >> >> + * writeback is queued.  If any are over the foreground dirty limit then >> >> + * throttle the dirtying task while writing dirty data.  The per-memcg dirty >> >> + * limits check by this routine are distinct from either the per-system, >> >> + * per-bdi, or per-task limits considered by balance_dirty_pages(). >> >> + */ >> >> +void mem_cgroup_balance_dirty_pages(struct address_space *mapping, >> >> +                              unsigned long write_chunk) >> >> +{ >> >> +  struct backing_dev_info *bdi = mapping->backing_dev_info; >> >> +  struct mem_cgroup *mem; >> >> +  struct mem_cgroup *ref_mem; >> >> +  struct dirty_info info; >> >> +  unsigned long nr_reclaimable; >> >> +  unsigned long sys_available_mem; >> >> +  unsigned long pause = 1; >> >> +  unsigned short id; >> >> +  bool over; >> >> +  bool shared_inodes; >> >> + >> >> +  if (mem_cgroup_disabled()) >> >> +          return; >> >> + >> >> +  sys_available_mem = determine_dirtyable_memory(); >> >> + >> >> +  /* reference the memcg so it is not deleted during this routine */ >> >> +  rcu_read_lock(); >> >> +  mem = mem_cgroup_from_task(current); >> >> +  if (mem && mem_cgroup_is_root(mem)) >> >> +          mem = NULL; >> >> +  if (mem) >> >> +          css_get(&mem->css); >> >> +  rcu_read_unlock(); >> >> +  ref_mem = mem; >> >> + >> >> +  /* balance entire ancestry of current's mem. */ >> >> +  for (; mem_cgroup_has_dirty_limit(mem); mem = parent_mem_cgroup(mem)) { >> >> +          id = css_id(&mem->css); >> >> + >> > >> > Hmm, this sounds natural...but...don't we need to restart checking from ref_mem's >> > dirty_ratio once we find an ancestor is over dirty_ratio and we slept ? >> > >> > Even if parent's dirty ratio comes to be clean state, children's may not. >> > So, I think some "restart loop" jump after io_schedule_timeout(). >> > >> > Thanks, >> > -Kame >> >> I do not think that we need to restart, but maybe you have a case in >> mind that I am not considering. >> >> Example hierarchy: >>               root >>          A            B >>      A1      A2 >>   A11 A12  A21 A22 >> >> Assume that mem_cgroup_balance_dirty_pages(A11), so ref_mem=A11. >> >> We start at A11 and walk up towards the root.  If A11 is over limit, >> then write A11 until under limit.  Next check A1, if over limit then >> write A1,A11,A12.  Then check A.  If A is over A limit, then we invoke >> writeback on A* until A is under A limit.  Are you concerned that while >> performing writeback on A* that other tasks may push A1 over the A1 >> limit?  Such other task writers would also be calling >> mem_cgroup_balance_dirty_pages() later. >> > > Hm, ok. Could you add comments to explain the algorithm ? > > Thanks, > -Kame No problem. I will add comments to this routine in -v9 to clarify.