kernel/linux.git/include/linux/blk-cgroup.h, branch linux-5.8.y

blk-iocost: switch to fixed non-auto-decaying use_delay

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

The use_delay mechanism was introduced by blk-iolatency to hold memory allocators accountable for the reclaim and other shared IOs they cause. The duration of the delay is dynamically balanced between iolatency increasing the value on each target miss and it auto-decaying as time passes and threads get delayed on it. While this works well for iolatency, iocost's control model isn't compatible with it. There is no repeated "violation" events which can be balanced against auto-decaying. iocost instead knows how much a given cgroup is over budget and wants to prevent that cgroup from issuing IOs while over budget. Until now, iocost has been adding the cost of force-issued IOs. However, this doesn't reflect the amount which is already over budget and is simply not enough to counter the auto-decaying allowing anon-memory leaking low priority cgroup to go over its alloted share of IOs. As auto-decaying doesn't make much sense for iocost, this patch introduces a different mode of operation for use_delay - when blkcg_set_delay() are used insted of blkcg_add/use_delay(), the delay duration is not auto-decayed until it is explicitly cleared with blkcg_clear_delay(). iocost is updated to keep the delay duration synchronized to the budget overage amount. With this change, iocost can effectively police cgroups which generate significant amount of force-issued IOs. Signed-off-by: Tejun Heo Cc: Josef Bacik Signed-off-by: Jens Axboe

block: replace BIO_QUEUE_ENTERED with BIO_CGROUP_ACCT

2020-04-29T15:33:26+00:00

BIO_QUEUE_ENTERED is only used for cgroup accounting now, so rename the flag and move setting it into the cgroup code. Signed-off-by: Christoph Hellwig Signed-off-by: Jens Axboe

blkcg: don't offline parent blkcg first

2020-04-01T20:56:44+00:00

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: Tejun Heo Signed-off-by: Jens Axboe

blkcg: rename blkcg->cgwb_refcnt to ->online_pin and always use it

2020-04-01T20:56:42+00:00

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: Tejun Heo Signed-off-by: Jens Axboe

blk-cgroup: remove blkcg_drain_queue

2019-12-12T16:26:55+00:00

Since blk_drain_queue had already been removed, so this function is not needed anymore. Signed-off-by: Guoqing Jiang Signed-off-by: Jens Axboe

blk-cgroup: cgroup_rstat_updated() shouldn't be called on cgroup1

2019-11-18T15:40:41+00:00

Currently, cgroup rstat is supported only on cgroup2 hierarchy and rstat functions shouldn't be called on cgroup1 cgroups. While converting blk-cgroup core statistics to rstat, f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") accidentally ended up calling cgroup_rstat_updated() on cgroup1 cgroups causing crashes. Longer term, we probably should add cgroup1 support to rstat but for now let's mask the call directly. Fixes: f73316482977 ("blk-cgroup: reimplement basic IO stats using cgroup rstat") Tested-by: Faiz Abbas Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

blk-cgroup: separate out blkg_rwstat under CONFIG_BLK_CGROUP_RWSTAT

2019-11-07T19:28:13+00:00

blkg_rwstat is now only used by bfq-iosched and blk-throtl when on cgroup1. Let's move it into its own files and gate it behind a config option. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

blk-cgroup: reimplement basic IO stats using cgroup rstat

2019-11-07T19:28:13+00:00

blk-cgroup has been using blkg_rwstat to track basic IO stats. Unfortunately, reading recursive stats scales badly as itinvolves walking all descendants. On systems with a huge number of cgroups (dead or alive), this can lead to substantial CPU cost when reading IO stats. This patch reimplements basic IO stats using cgroup rstat which uses more memory but makes recursive stat reading O(# descendants which have been active since last reading) instead of O(# descendants). * blk-cgroup core no longer uses sync/async stats. Introduce new stat enums - BLKG_IOSTAT_{READ|WRITE|DISCARD}. * Add blkg_iostat[_set] which encapsulates byte and io stats, last values for propagation delta calculation and u64_stats_sync for correctness on 32bit archs. * Update the new percpu stat counters directly and implement blkcg_rstat_flush() to implement propagation. * blkg_print_stat() can now bring the stats up to date by calling cgroup_rstat_flush() and print them instead of directly summing up all descendants. * It now allocates 96 bytes per cpu. It used to be 40 bytes. Signed-off-by: Tejun Heo Cc: Dan Schatzberg Cc: Daniel Xu Signed-off-by: Jens Axboe

blk-cgroup: remove now unused blkg_print_stat_{bytes|ios}_recursive()

2019-11-07T19:28:13+00:00

These don't have users anymore. Remove them. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe

blkcg: separate blkcg_conf_get_disk() out of blkg_conf_prep()

2019-08-29T03:17:04+00:00

Separate out blkcg_conf_get_disk() so that it can be used by blkcg policy interface file input parsers before the policy is actually enabled. This doesn't introduce any functional changes. Signed-off-by: Tejun Heo Signed-off-by: Jens Axboe