1. 08 Jun, 2018 2 commits
  2. 10 Jul, 2017 1 commit
    • David Rientjes's avatar
      mm, vmpressure: pass-through notification support · b6bb9811
      David Rientjes authored
      By default, vmpressure events are not pass-through, i.e.  they propagate
      up through the memcg hierarchy until an event notifier is found for any
      threshold level.
      
      This presents a difficulty when a thread waiting on a read(2) for a
      vmpressure event cannot distinguish between local memory pressure and
      memory pressure in a descendant memcg, especially when that thread may
      not control the memcg hierarchy.
      
      Consider a user-controlled child memcg with a smaller limit than a
      top-level memcg controlled by the "Activity Manager" specified in
      Documentation/cgroup-v1/memory.txt.  It may register for memory pressure
      notification for descendant memcgs to make a policy decision: oom kill a
      low priority job, increase the limit, decrease other limits, etc.  If it
      registers for memory pressure notification on the top-level memcg, it
      currently cannot distinguish between memory pressure in its own memcg or
      a descendant memcg, which is user-controlled.
      
      Conversely, if a user registers for memory pressure notification on
      their own descendant memcg, the Activity Manager does not receive any
      pressure notification for that child memcg hierarchy.  Vmpressure events
      are not received for ancestor memcgs if the memcg experiencing pressure
      have notifiers registered, perhaps outside the knowledge of the thread
      waiting on read(2) at the top level.
      
      Both of these are consequences of vmpressure notification not being
      pass-through.
      
      This implements a pass-through behavior for vmpressure events.  When
      writing to control.event_control, vmpressure event handlers may
      optionally specify a mode.  There are two new modes:
      
       - "hierarchy": always propagate memory pressure events up the hierarchy
         regardless if descendant memcgs have their own notifiers registered,
         and
      
       - "local": only receive notifications when the memcg for which the
         event is registered experiences memory pressure.
      
      Of course, processes may register for one notification of "low,local",
      for example, and another for "low".
      
      If no mode is specified, the current behavior is maintained for
      backwards compatibility.
      
      See the change to Documentation/cgroup-v1/memory.txt for full
      specification.
      
      [dan.carpenter@oracle.com: free the same pointer we allocated]
        Link: http://lkml.kernel.org/r/20170613191820.GA20003@elgon.mountain
      Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1705311421320.8946@chino.kir.corp.google.comSigned-off-by: default avatarDavid Rientjes <rientjes@google.com>
      Signed-off-by: default avatarDan Carpenter <dan.carpenter@oracle.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Vlastimil Babka <vbabka@suse.cz>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Jonathan Corbet <corbet@lwn.net>
      Cc: Anton Vorontsov <anton@enomsg.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      b6bb9811
  3. 16 Jun, 2017 1 commit
  4. 25 Feb, 2017 1 commit
  5. 03 Feb, 2016 1 commit
  6. 21 Jan, 2016 2 commits
  7. 15 Jan, 2016 2 commits
  8. 03 Dec, 2014 1 commit
  9. 03 Feb, 2014 1 commit
    • Tejun Heo's avatar
      arm, pm, vmpressure: add missing slab.h includes · 1ff6bbfd
      Tejun Heo authored
      arch/arm/mach-tegra/pm.c, kernel/power/console.c and mm/vmpressure.c
      were somehow getting slab.h indirectly through cgroup.h which in turn
      was getting it indirectly through xattr.h.  A scheduled cgroup change
      drops xattr.h inclusion from cgroup.h and breaks compilation of these
      three files.  Add explicit slab.h includes to the three files.
      
      A pending cgroup patch depends on this change and it'd be great if
      this can be routed through cgroup/for-3.14-fixes branch.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarStephen Warren <swarren@wwwdotorg.org>
      Cc: Thierry Reding <thierry.reding@gmail.com>
      Cc: linux-tegra@vger.kernel.org
      Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
      Cc: linux-pm@vger.kernel.org
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: cgroups@vger.kernel.org
      1ff6bbfd
  10. 22 Nov, 2013 2 commits
  11. 09 Aug, 2013 3 commits
    • Tejun Heo's avatar
      cgroup: make cftype->[un]register_event() deal with cgroup_subsys_state instead of cgroup · 81eeaf04
      Tejun Heo authored
      cgroup is in the process of converting to css (cgroup_subsys_state)
      from cgroup as the principal subsystem interface handle.  This is
      mostly to prepare for the unified hierarchy support where css's will
      be created and destroyed dynamically but also helps cleaning up
      subsystem implementations as css is usually what they are interested
      in anyway.
      
      cftype->[un]register_event() is among the remaining couple interfaces
      which still use struct cgroup.  Convert it to cgroup_subsys_state.
      The conversion is mostly mechanical and removes the last users of
      mem_cgroup_from_cont() and cg_to_vmpressure(), which are removed.
      
      v2: indentation update as suggested by Li Zefan.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarLi Zefan <lizefan@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Balbir Singh <bsingharora@gmail.com>
      81eeaf04
    • Tejun Heo's avatar
      cgroup: pass around cgroup_subsys_state instead of cgroup in file methods · 182446d0
      Tejun Heo authored
      cgroup is currently in the process of transitioning to using struct
      cgroup_subsys_state * as the primary handle instead of struct cgroup.
      Please see the previous commit which converts the subsystem methods
      for rationale.
      
      This patch converts all cftype file operations to take @css instead of
      @cgroup.  cftypes for the cgroup core files don't have their subsytem
      pointer set.  These will automatically use the dummy_css added by the
      previous patch and can be converted the same way.
      
      Most subsystem conversions are straight forwards but there are some
      interesting ones.
      
      * freezer: update_if_frozen() is also converted to take @css instead
        of @cgroup for consistency.  This will make the code look simpler
        too once iterators are converted to use css.
      
      * memory/vmpressure: mem_cgroup_from_css() needs to be exported to
        vmpressure while mem_cgroup_from_cont() can be made static.
        Updated accordingly.
      
      * cpu: cgroup_tg() doesn't have any user left.  Removed.
      
      * cpuacct: cgroup_ca() doesn't have any user left.  Removed.
      
      * hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
        Removed.
      
      * net_cls: cgrp_cls_state() doesn't have any user left.  Removed.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarLi Zefan <lizefan@huawei.com>
      Acked-by: default avatarMichal Hocko <mhocko@suse.cz>
      Acked-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Acked-by: default avatarAristeu Rozanski <aris@redhat.com>
      Acked-by: default avatarDaniel Wagner <daniel.wagner@bmw-carit.de>
      Cc: Peter Zijlstra <peterz@infradead.org>
      Cc: Ingo Molnar <mingo@redhat.com>
      Cc: Johannes Weiner <hannes@cmpxchg.org>
      Cc: Balbir Singh <bsingharora@gmail.com>
      Cc: Matt Helsley <matthltc@us.ibm.com>
      Cc: Jens Axboe <axboe@kernel.dk>
      Cc: Steven Rostedt <rostedt@goodmis.org>
      182446d0
    • Tejun Heo's avatar
      cgroup: s/cgroup_subsys_state/cgroup_css/ s/task_subsys_state/task_css/ · 8af01f56
      Tejun Heo authored
      The names of the two struct cgroup_subsys_state accessors -
      cgroup_subsys_state() and task_subsys_state() - are somewhat awkward.
      The former clashes with the type name and the latter doesn't even
      indicate it's somehow related to cgroup.
      
      We're about to revamp large portion of cgroup API, so, let's rename
      them so that they're less awkward.  Most per-controller usages of the
      accessors are localized in accessor wrappers and given the amount of
      scheduled changes, this isn't gonna add any noticeable headache.
      
      Rename cgroup_subsys_state() to cgroup_css() and task_subsys_state()
      to task_css().  This patch is pure rename.
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      Acked-by: default avatarLi Zefan <lizefan@huawei.com>
      8af01f56
  12. 31 Jul, 2013 3 commits
  13. 29 Apr, 2013 1 commit
    • Anton Vorontsov's avatar
      memcg: add memory.pressure_level events · 70ddf637
      Anton Vorontsov authored
      With this patch userland applications that want to maintain the
      interactivity/memory allocation cost can use the pressure level
      notifications.  The levels are defined like this:
      
      The "low" level means that the system is reclaiming memory for new
      allocations.  Monitoring this reclaiming activity might be useful for
      maintaining cache level.  Upon notification, the program (typically
      "Activity Manager") might analyze vmstat and act in advance (i.e.
      prematurely shutdown unimportant services).
      
      The "medium" level means that the system is experiencing medium memory
      pressure, the system might be making swap, paging out active file
      caches, etc.  Upon this event applications may decide to further analyze
      vmstat/zoneinfo/memcg or internal memory usage statistics and free any
      resources that can be easily reconstructed or re-read from a disk.
      
      The "critical" level means that the system is actively thrashing, it is
      about to out of memory (OOM) or even the in-kernel OOM killer is on its
      way to trigger.  Applications should do whatever they can to help the
      system.  It might be too late to consult with vmstat or any other
      statistics, so it's advisable to take an immediate action.
      
      The events are propagated upward until the event is handled, i.e.  the
      events are not pass-through.  Here is what this means: for example you
      have three cgroups: A->B->C.  Now you set up an event listener on
      cgroups A, B and C, and suppose group C experiences some pressure.  In
      this situation, only group C will receive the notification, i.e.  groups
      A and B will not receive it.  This is done to avoid excessive
      "broadcasting" of messages, which disturbs the system and which is
      especially bad if we are low on memory or thrashing.  So, organize the
      cgroups wisely, or propagate the events manually (or, ask us to
      implement the pass-through events, explaining why would you need them.)
      
      Performance wise, the memory pressure notifications feature itself is
      lightweight and does not require much of bookkeeping, in contrast to the
      rest of memcg features.  Unfortunately, as of current memcg
      implementation, pages accounting is an inseparable part and cannot be
      turned off.  The good news is that there are some efforts[1] to improve
      the situation; plus, implementing the same, fully API-compatible[2]
      interface for CONFIG_MEMCG=n case (e.g.  embedded) is also a viable
      option, so it will not require any changes on the userland side.
      
      [1] http://permalink.gmane.org/gmane.linux.kernel.cgroups/6291
      [2] http://lkml.org/lkml/2013/2/21/454
      
      [akpm@linux-foundation.org: coding-style fixes]
      [akpm@linux-foundation.org: fix CONFIG_CGROPUPS=n warnings]
      Signed-off-by: default avatarAnton Vorontsov <anton.vorontsov@linaro.org>
      Acked-by: default avatarKirill A. Shutemov <kirill@shutemov.name>
      Acked-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
      Cc: Tejun Heo <tj@kernel.org>
      Cc: David Rientjes <rientjes@google.com>
      Cc: Pekka Enberg <penberg@kernel.org>
      Cc: Mel Gorman <mgorman@suse.de>
      Cc: Glauber Costa <glommer@parallels.com>
      Cc: Michal Hocko <mhocko@suse.cz>
      Cc: Luiz Capitulino <lcapitulino@redhat.com>
      Cc: Greg Thelen <gthelen@google.com>
      Cc: Leonid Moiseichuk <leonid.moiseichuk@nokia.com>
      Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
      Cc: Minchan Kim <minchan@kernel.org>
      Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
      Cc: John Stultz <john.stultz@linaro.org>
      Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      70ddf637