1. 18 Aug, 2017 32 commits
  2. 17 Aug, 2017 2 commits
  3. 15 Aug, 2017 1 commit
  4. 11 Aug, 2017 3 commits
    • Ritesh Harjani's avatar
      cfq: Give a chance for arming slice idle timer in case of group_idle · b3193bc0
      Ritesh Harjani authored
      In below scenario blkio cgroup does not work as per their assigned
      weights :-
      1. When the underlying device is nonrotational with a single HW queue
      with depth of >= CFQ_HW_QUEUE_MIN
      2. When the use case is forming two blkio cgroups cg1(weight 1000) &
      cg2(wight 100) and two processes(file1 and file2) doing sync IO in
      their respective blkio cgroups.
      
      For above usecase result of fio (without this patch):-
      file1: (groupid=0, jobs=1): err= 0: pid=685: Thu Jan  1 19:41:49 1970
        write: IOPS=1315, BW=41.1MiB/s (43.1MB/s)(1024MiB/24906msec)
      <...>
      file2: (groupid=0, jobs=1): err= 0: pid=686: Thu Jan  1 19:41:49 1970
        write: IOPS=1295, BW=40.5MiB/s (42.5MB/s)(1024MiB/25293msec)
      <...>
      // both the process BW is equal even though they belong to diff.
      cgroups with weight of 1000(cg1) and 100(cg2)
      
      In above case (for non rotational NCQ devices),
      as soon as the request from cg1 is completed and even
      though it is provided with higher set_slice=10, because of CFQ
      algorithm when the driver tries to fetch the request, CFQ expires
      this group without providing any idle time nor weight priority
      and schedules another cfq group (in this case cg2).
      And thus both cfq groups(cg1 & cg2) keep alternating to get the
      disk time and hence loses the cgroup weight based scheduling.
      
      Below patch gives a chance to cfq algorithm (cfq_arm_slice_timer)
      to arm the slice timer in case group_idle is enabled.
      In case if group_idle is also not required (including for nonrotational
      NCQ drives), we need to explicitly set group_idle = 0 from sysfs for
      such cases.
      
      With this patch result of fio(for above usecase) :-
      file1: (groupid=0, jobs=1): err= 0: pid=690: Thu Jan  1 00:06:08 1970
        write: IOPS=1706, BW=53.3MiB/s (55.9MB/s)(1024MiB/19197msec)
      <..>
      file2: (groupid=0, jobs=1): err= 0: pid=691: Thu Jan  1 00:06:08 1970
        write: IOPS=1043, BW=32.6MiB/s (34.2MB/s)(1024MiB/31401msec)
      <..>
      // In this processes BW is as per their respective cgroups weight.
      Signed-off-by: default avatarRitesh Harjani <riteshh@codeaurora.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      b3193bc0
    • Paolo Valente's avatar
      block, bfq: boost throughput with flash-based non-queueing devices · edaf9428
      Paolo Valente authored
      When a queue associated with a process remains empty, there are cases
      where throughput gets boosted if the device is idled to await the
      arrival of a new I/O request for that queue. Currently, BFQ assumes
      that one of these cases is when the device has no internal queueing
      (regardless of the properties of the I/O being served). Unfortunately,
      this condition has proved to be too general. So, this commit refines it
      as "the device has no internal queueing and is rotational".
      
      This refinement provides a significant throughput boost with random
      I/O, on flash-based storage without internal queueing. For example, on
      a HiKey board, throughput increases by up to 125%, growing, e.g., from
      6.9MB/s to 15.6MB/s with two or three random readers in parallel.
      Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
      Signed-off-by: default avatarLuca Miccio <lucmiccio@gmail.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      edaf9428
    • Paolo Valente's avatar
      block,bfq: refactor device-idling logic · d5be3fef
      Paolo Valente authored
      The logic that decides whether to idle the device is scattered across
      three functions. Almost all of the logic is in the function
      bfq_bfqq_may_idle, but (1) part of the decision is made in
      bfq_update_idle_window, and (2) the function bfq_bfqq_must_idle may
      switch off idling regardless of the output of bfq_bfqq_may_idle. In
      addition, both bfq_update_idle_window and bfq_bfqq_must_idle make
      their decisions as a function of parameters that are used, for similar
      purposes, also in bfq_bfqq_may_idle. This commit addresses these
      issues by moving all the logic into bfq_bfqq_may_idle.
      Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
      d5be3fef
  5. 10 Aug, 2017 1 commit
  6. 09 Aug, 2017 1 commit