1. 21 Mar, 2012 18 commits
  2. 20 Mar, 2012 7 commits
  3. 19 Mar, 2012 1 commit
  4. 18 Mar, 2012 3 commits
    • Mark A. Grondona's avatar
      task/cgroup: delete job step memcg instead of using force_empty · a93afcd1
      Mark A. Grondona authored
      The current task/cgroup memory code writes to force_empty at job step
      completion and then waits for the release agent to be triggered to
      remove the memcg. However, force_empty only causes clean cache pages
      to be dropped from the memcg and does not actually move charges to
      the parent [1].
      
      This has two unfortunate side-effects. First, pages that can't be
      dropped by force_empty are in-use and could stay that way indefinitely
      (e.g. system library that is in-use until just after force_empty
      completes). Thus, the step memcg never becomes 'empty' and the release
      agent is not activated. Second, cached pages that can be freed are
      likely associated with the job itself, and those files and libraries
      will have to be paged in again for subsequent job steps.
      
      In contrast, calling rmdir(2) on a memcg with no active tasks
      causes *all* current charges to move to parent, which is really what
      we want in this case. This allows cached libraries and binaries to
      stay resident and be associated with the job, and also ensures that
      the step memcg is removed immediately as the job step ends.
      
      Thus, this patch replaces the write to force_empty with a call
      to xcgroup_delete() on the step memcg, which in turn removes
      the memcg with rmdir(2).
      
      The functionality of this patch depends on the previous fix that
      uses xcgroup_move_process() to move slurmstepd to the root memcg.
      Otherwise, there will be leftover slurmstepd threads in the job
      step memcg, and the rmdir will fail with EBUSY.
      
       [1] Sec 4.3: http://www.kernel.org/doc/Documentation/cgroups/memory.txt
      a93afcd1
    • Mark A. Grondona's avatar
      task/cgroup: use xcgroup_move_process to move slurmstepd to root memcg · 2dd13506
      Mark A. Grondona authored
      In task_cgroup_memory_fini() the implementation attempts to move
      the existing slurmstepd task to the root memory cgroup by writing
      the result of getpid(2) to the root memory's 'task' file. This
      does not work, however, because slurmstepd is multi-threaded and
      thus only the main thread is moved.
      
      This patch replaces the explicit write to 'tasks' with a call to
      the new xcgroup_move_process() call, which handles moving all
      threads in the process.
      2dd13506
    • Mark A. Grondona's avatar
      xcgroup: add xcgroup_move_process helper function · aa912e4a
      Mark A. Grondona authored
      This patch adds a helper function to common/xcgroup.c to aid
      in moving processes between cgroups. If the cgroups.procs file
      is writable then writing the PID to that file is used, as this
      method moves all threads in a process atomically.
      
      If cgroups.procs is not writable, then each thread must be moved
      individually by walking the /proc/PID/task/ directory and writing
      each taskid individually to the 'tasks' file in the cgroup. The
      second method is racy if a process is concurrently creating
      threads, but it is better than the current method of just moving
      one of the process's threads.
      aa912e4a
  5. 16 Mar, 2012 11 commits