Skip to content

K
Kernel

openeuler / Kernel
接近 3 年 前同步成功

通知 11
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 10 5月, 2020 1 次提交
  3. 05 5月, 2020 1 次提交
    • T
      iocost: protect iocg->abs_vdebt with iocg->waitq.lock · 0b80f986
      由 Tejun Heo 提交于 
      abs_vdebt is an atomic_64 which tracks how much over budget a given cgroup
is and controls the activation of use_delay mechanism. Once a cgroup goes
over budget from forced IOs, it has to pay it back with its future budget.
The progress guarantee on debt paying comes from the iocg being active -
active iocgs are processed by the periodic timer, which ensures that as time
passes the debts dissipate and the iocg returns to normal operation.

However, both iocg activation and vdebt handling are asynchronous and a
sequence like the following may happen.

1. The iocg is in the process of being deactivated by the periodic timer.

2. A bio enters ioc_rqos_throttle(), calls iocg_activate() which returns
   without anything because it still sees that the iocg is already active.

3. The iocg is deactivated.

4. The bio from #2 is over budget but needs to be forced. It increases
   abs_vdebt and goes over the threshold and enables use_delay.

5. IO control is enabled for the iocg's subtree and now IOs are attributed
   to the descendant cgroups and the iocg itself no longer issues IOs.

This leaves the iocg with stuck abs_vdebt - it has debt but inactive and no
further IOs which can activate it. This can end up unduly punishing all the
descendants cgroups.

The usual throttling path has the same issue - the iocg must be active while
throttled to ensure that future event will wake it up - and solves the
problem by synchronizing the throttling path with a spinlock. abs_vdebt
handling is another form of overage handling and shares a lot of
characteristics including the fact that it isn't in the hottest path.

This patch fixes the above and other possible races by strictly
synchronizing abs_vdebt and use_delay handling with iocg->waitq.lock.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NVlad Dmitriev <vvd@fb.com>
Cc: stable@vger.kernel.org # v5.4+
Fixes: e1518f63 ("blk-iocost: Don't let merges push vtime into the future")
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      0b80f986
  5. 01 5月, 2020 1 次提交
  7. 21 4月, 2020 1 次提交
    • W
      blk-iocost: Fix error on iocost_ioc_vrate_adj · d6c8e949
      由 Waiman Long 提交于 
      Systemtap 4.2 is unable to correctly interpret the "u32 (*missed_ppm)[2]"
argument of the iocost_ioc_vrate_adj trace entry defined in
include/trace/events/iocost.h leading to the following error:

  /tmp/stapAcz0G0/stap_c89c58b83cea1724e26395efa9ed4939_6321_aux_6.c:78:8:
  error: expected ‘;’, ‘,’ or ‘)’ before ‘*’ token
   , u32[]* __tracepoint_arg_missed_ppm

That argument type is indeed rather complex and hard to read. Looking
at block/blk-iocost.c. It is just a 2-entry u32 array. By simplifying
the argument to a simple "u32 *missed_ppm" and adjusting the trace
entry accordingly, the compilation error was gone.

Fixes: 7caa4715 ("blkcg: implement blk-iocost")
Acked-by: NSteven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NWaiman Long <longman@redhat.com>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      d6c8e949
  9. 17 4月, 2020 1 次提交
  11. 16 4月, 2020 1 次提交
  13. 10 4月, 2020 1 次提交
  15. 08 4月, 2020 1 次提交
  17. 07 4月, 2020 1 次提交
  19. 02 4月, 2020 2 次提交
    • T
      blkcg: don't offline parent blkcg first · 4308a434
      由 Tejun Heo 提交于 
      blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs
don't get offlined while there are active cgwbs on them.  However, it
ends up making offlining unordered sometimes causing parents to be
offlined before children.

Let's fix this by making child blkcgs pin the parents' online states.

Note that pin/unpin names are chosen over get/put intentionally
because css uses get/put online for something different.
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      4308a434
    • T
      blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it · d866dbf6
      由 Tejun Heo 提交于 
      blkcg->cgwb_refcnt is used to delay blkcg offlining so that blkgs
don't get offlined while there are active cgwbs on them.  However, it
ends up making offlining unordered sometimes causing parents to be
offlined before children.

To fix it, we want child blkcgs to pin the parents' online states
turning the refcnt into a more generic online pinning mechanism.

In prepartion,

* blkcg->cgwb_refcnt -> blkcg->online_pin
* blkcg_cgwb_get/put() -> blkcg_pin/unpin_online()
* Take them out of CONFIG_CGROUP_WRITEBACK
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NJens Axboe <axboe@kernel.dk>
      d866dbf6
  21. 30 3月, 2020 1 次提交
  23. 28 3月, 2020 5 次提交
  25. 27 3月, 2020 1 次提交
  27. 25 3月, 2020 12 次提交
  29. 24 3月, 2020 10 次提交