lwn.git/tools/cgroup/iocost_monitor.py, branch docs-mw

iocost_monitor: improve it by adding iocg wait_ms

2023-08-08T21:43:03+00:00

The iocg can have three throttled metrics: wait, debt, delay. This patch add missing wait_ms to IocgStat to show the latest wait_ms of iocg. As we are here, group iocg usage percents "inflt%" and "usage%" together, and group iocg throttled metrics "wait", "debt" and "delay" together. Effect after changes: nvme0n1 RUN per=50.0ms cur_per=177105.713:v1053528.587 busy= +0 vrate=135.00%:270.00% params=ssd_dfl(CQ) active weight hweight% inflt% usage% wait debt delay InterfererGroup0 * 100/ 100 54.28/ 9.09 0.34 24.07 0.00 0.00 0.00 interfered * 84/ 1000 45.72/ 90.91 0.48 41.09 0.00 0.00 0.00 Signed-off-by: Chengming Zhou Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20230804065039.8885-3-chengming.zhou@linux.dev Signed-off-by: Jens Axboe

iocost_monitor: print vrate inuse along with base_vrate

2023-08-08T21:43:03+00:00

The real vrate iocost inuse is not base_vrate, but the atomic vtime_rate. We need iocost_monitor tool to display this real vrate that iocost use, to check if the boosted compensated vrate is normal. Effect after change: nvme0n1 RUN per=50.0ms cur_per=172116.580:v1040587.433 busy= +0 \ vrate=135.00%:270.00% params=ssd_dfl(CQ) ^ | this is real vrate inuse Signed-off-by: Chengming Zhou Link: https://lore.kernel.org/r/20230804065039.8885-2-chengming.zhou@linux.dev Signed-off-by: Jens Axboe

iocost_monitor: fix kernel queue kobj changes

2023-08-08T21:43:03+00:00

When I use iocost_monitor on nvme0n1, this error shows up: "Could not find ioc for nvme0n1" There is no kobj in struct queue in recent kernel, it seems that the commit 2bd85221a625 ("block: untangle request_queue refcounting from sysfs") move the queue kobj to struct gendisk. Fix it by using mq_kobj which is at the same level with queue kobj. Signed-off-by: Chengming Zhou Link: https://lore.kernel.org/r/20230804065039.8885-1-chengming.zhou@linux.dev Signed-off-by: Jens Axboe

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