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workqueue: Control intensive warning threshold through cmdline

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When CONFIG_WQ_CPU_INTENSIVE_REPORT is set, the kernel will report
the work functions which violate the intensive_threshold_us repeatedly.
And now, only when the violate times exceed 4 and is a power of 2,
the kernel warning could be triggered.

However, sometimes, even if a long work execution time occurs only once,
it may cause other work to be delayed for a long time. This may also
cause some problems sometimes.

In order to freely control the threshold of warninging, a boot argument
is added so that the user can control the warning threshold to be printed.
At the same time, keep the exponential backoff to prevent reporting too much.

By default, the warning threshold is 4.

tj: Updated kernel-parameters.txt description.

Signed-off-by: Xuewen Yan <xuewen.yan@unisoc.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Xuewen Yan
2024-02-22 15:28:08 +08:00
committed by Tejun Heo
parent bccdc1faaf
commit ccdec92198
2 changed files with 20 additions and 3 deletions
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14
kernel/workqueue.c
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@@ -409,6 +409,10 @@ static const char *wq_affn_names[WQ_AFFN_NR_TYPES] = {
*/
static unsigned long wq_cpu_intensive_thresh_us = ULONG_MAX;
module_param_named(cpu_intensive_thresh_us, wq_cpu_intensive_thresh_us, ulong, 0644);
#ifdef CONFIG_WQ_CPU_INTENSIVE_REPORT
static unsigned int wq_cpu_intensive_warning_thresh = 4;
module_param_named(cpu_intensive_warning_thresh, wq_cpu_intensive_warning_thresh, uint, 0644);
#endif
/* see the comment above the definition of WQ_POWER_EFFICIENT */
static bool wq_power_efficient = IS_ENABLED(CONFIG_WQ_POWER_EFFICIENT_DEFAULT);
@@ -1327,11 +1331,13 @@ restart:
u64 cnt;
/*
* Start reporting from the fourth time and back off
* Start reporting from the warning_thresh and back off
* exponentially.
*/
cnt = atomic64_inc_return_relaxed(&ent->cnt);
if (cnt >= 4 && is_power_of_2(cnt))
if (wq_cpu_intensive_warning_thresh &&
cnt >= wq_cpu_intensive_warning_thresh &&
is_power_of_2(cnt + 1 - wq_cpu_intensive_warning_thresh))
printk_deferred(KERN_WARNING "workqueue: %ps hogged CPU for >%luus %llu times, consider switching to WQ_UNBOUND\n",
ent->func, wq_cpu_intensive_thresh_us,
atomic64_read(&ent->cnt));
@@ -1360,10 +1366,12 @@ restart:
ent = &wci_ents[wci_nr_ents++];
ent->func = func;
atomic64_set(&ent->cnt, 1);
atomic64_set(&ent->cnt, 0);
hash_add_rcu(wci_hash, &ent->hash_node, (unsigned long)func);
raw_spin_unlock(&wci_lock);
goto restart;
}
#else /* CONFIG_WQ_CPU_INTENSIVE_REPORT */