Messages in this thread | | | From | Geert Uytterhoeven <> | Date | Tue, 11 Jul 2023 15:55:26 +0200 | Subject | Consider switching to WQ_UNBOUND messages (was: Re: [PATCH v2 6/7] workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism) |
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Hi Tejun,
On Fri, May 12, 2023 at 9:54 PM Tejun Heo <tj@kernel.org> wrote: > Workqueue now automatically marks per-cpu work items that hog CPU for too > long as CPU_INTENSIVE, which excludes them from concurrency management and > prevents stalling other concurrency-managed work items. If a work function > keeps running over the thershold, it likely needs to be switched to use an > unbound workqueue. > > This patch adds a debug mechanism which tracks the work functions which > trigger the automatic CPU_INTENSIVE mechanism and report them using > pr_warn() with exponential backoff. > > v2: Drop bouncing through kthread_worker for printing messages. It was to > avoid introducing circular locking dependency but wasn't effective as it > still had pool lock -> wci_lock -> printk -> pool lock loop. Let's just > print directly using printk_deferred(). > > Signed-off-by: Tejun Heo <tj@kernel.org> > Suggested-by: Peter Zijlstra <peterz@infradead.org>
Thanks for your patch, which is now commit 6363845005202148 ("workqueue: Report work funcs that trigger automatic CPU_INTENSIVE mechanism") in v6.5-rc1.
I guess you are interested to know where this triggers. I enabled CONFIG_WQ_CPU_INTENSIVE_REPORT=y, and tested the result on various machines...
SH/R-Mobile:
workqueue: genpd_power_off_work_fn hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
Atmark Techno Armadillo800-EVA with shmob_drm:
workqueue: drm_fb_helper_damage_work hogged CPU for >10000us 16 times, consider switching to WQ_UNBOUND
R-Car Gen2:
workqueue: rtc_timer_do_work hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
R-Car Gen2/Gen3:
workqueue: pm_runtime_work hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
R-Car Gen3:
workqueue: kfree_rcu_work hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND
OrangeCrab/Linux-on-LiteX-VexRiscV with ht16k33 14-seg display and ssd130xdrmfb:
workqueue: check_lifetime hogged CPU for >10000us 4 times, consider switching to WQ_UNBOUND workqueue: drm_fb_helper_damage_work hogged CPU for >10000us 1024 times, consider switching to WQ_UNBOUND workqueue: fb_flashcursor hogged CPU for >10000us 128 times, consider switching to WQ_UNBOUND workqueue: ht16k33_seg14_update hogged CPU for >10000us 128 times, consider switching to WQ_UNBOUND workqueue: mmc_rescan hogged CPU for >10000us 128 times, consider switching to WQ_UNBOUND
Atari (ARAnyM):
workqueue: ata_sff_pio_task hogged CPU for >10000us 64 times, consider switching to WQ_UNBOUND
The OrangeCrab is a slow machine, so it's not that surprising to see these messages...
Gr{oetje,eeting}s,
Geert
-- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds
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