linux-toradex.git/tools/cgroup/iocost_monitor.py, branch v6.3

iocost_monitor: reorder BlkgIterator

2022-09-24T02:57:10+00:00

In order to comply with PEP 8, the first parameter of a class should be
__init__.

Signed-off-by: Elijah Conners 
Signed-off-by: Tejun Heo

blk-iocost: update iocost_monitor.py

2020-09-02T01:38:33+00:00

iocost went through significant internal changes. Update iocost_monitor.py
accordingly.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iocost_monitor: start from the oldest usage index

2020-07-30T17:45:29+00:00

iocg usage_idx is the latest usage index, we should start from the
oldest usage index to show the consecutive NR_USAGE_SLOTS usages.

Signed-off-by: Chengming Zhou 
Acked-by: Tejun Heo 
Signed-off-by: Jens Axboe

Merge branch 'block-5.7' into for-5.8/block

2020-05-09T22:13:58+00:00

Pull in block-5.7 fixes for 5.8. Mostly to resolve a conflict with
the blk-iocost changes, but we also need the base of the bdi
use-after-free as well as we build on top of it.

* block-5.7:
  nvme: fix possible hang when ns scanning fails during error recovery
  nvme-pci: fix "slimmer CQ head update"
  bdi: add a ->dev_name field to struct backing_dev_info
  bdi: use bdi_dev_name() to get device name
  bdi: move bdi_dev_name out of line
  vboxsf: don't use the source name in the bdi name
  iocost: protect iocg->abs_vdebt with iocg->waitq.lock
  block: remove the bd_openers checks in blk_drop_partitions
  nvme: prevent double free in nvme_alloc_ns() error handling
  null_blk: Cleanup zoned device initialization
  null_blk: Fix zoned command handling
  block: remove unused header
  blk-iocost: Fix error on iocost_ioc_vrate_adj
  bdev: Reduce time holding bd_mutex in sync in blkdev_close()
  buffer: remove useless comment and WB_REASON_FREE_MORE_MEM, reason.

Signed-off-by: Jens Axboe

iocost: protect iocg->abs_vdebt with iocg->waitq.lock

2020-05-05T15:23:18+00:00

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: Tejun Heo 
Reported-by: Vlad Dmitriev 
Cc: stable@vger.kernel.org # v5.4+
Fixes: e1518f63f246 ("blk-iocost: Don't let merges push vtime into the future")
Signed-off-by: Jens Axboe

iocost_monitor: drop string wrap around numbers when outputting json

2020-04-30T21:54:45+00:00

Wrapping numbers in strings is used by some to work around bit-width issues in
some enviroments. The problem isn't innate to json and the workaround seems to
cause more integration problems than help. Let's drop the string wrapping.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iocost_monitor: exit successfully if interval is zero

2020-04-30T21:54:45+00:00

This is to help external tools to decide whether iocost_monitor has all its
requirements met or not based on the exit status of an -i0 run.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iocost: Fix iocost_monitor.py due to helper type mismatch

2020-01-17T19:54:35+00:00

iocost_monitor.py broke with recent versions of drgn due to helper
being stricter about types.  Fix it so that it uses the correct type.

Signed-off-by: Tejun Heo 
Suggested-by: Omar Sandoval

iocost_monitor: Report debt

2019-09-10T18:31:39+00:00

Report debt and rename del_ms row to delay for consistency.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe

iocost_monitor: Report more info with higher accuracy

2019-09-10T18:31:39+00:00

When outputting json:

* Don't truncate numbers.

* Report address of iocg to ease drilling down further.

When outputting table:

* Use math.ceil() for delay_ms so that small delays don't read as 0.

Signed-off-by: Tejun Heo 
Signed-off-by: Jens Axboe