From ace3c5499e61ef7c0433a7a297227a9bdde54a55 Mon Sep 17 00:00:00 2001 From: tiozhang Date: Thu, 29 Jun 2023 11:50:50 +0800 Subject: [PATCH] workqueue: add cmdline parameter `workqueue.unbound_cpus` to further constrain wq_unbound_cpumask at boot time Motivation of doing this is to better improve boot times for devices when we want to prevent our workqueue works from running on some specific CPUs, e,g, some CPUs are busy with interrupts. Signed-off-by: tiozhang Signed-off-by: Tejun Heo --- Documentation/admin-guide/kernel-parameters.txt | 7 +++++++ kernel/workqueue.c | 17 +++++++++++++++++ 2 files changed, 24 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index a145799..d1edee0 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -6964,6 +6964,13 @@ disables both lockup detectors. Default is 10 seconds. + workqueue.unbound_cpus= + [KNL,SMP] Specify to constrain one or some CPUs + to use in unbound workqueues. + Format: + By default, all online CPUs are available for + unbound workqueues. + workqueue.watchdog_thresh= If CONFIG_WQ_WATCHDOG is configured, workqueue can warn stall conditions and dump internal state to diff --git a/kernel/workqueue.c b/kernel/workqueue.c index f889155..83f8993 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -368,6 +368,9 @@ static bool workqueue_freezing; /* PL: have wqs started freezing? */ /* PL&A: allowable cpus for unbound wqs and work items */ static cpumask_var_t wq_unbound_cpumask; +/* for further constrain wq_unbound_cpumask by cmdline parameter*/ +static struct cpumask wq_cmdline_cpumask __initdata; + /* CPU where unbound work was last round robin scheduled from this CPU */ static DEFINE_PER_CPU(int, wq_rr_cpu_last); @@ -6455,6 +6458,9 @@ void __init workqueue_init_early(void) cpumask_copy(wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_WQ)); cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, housekeeping_cpumask(HK_TYPE_DOMAIN)); + if (!cpumask_empty(&wq_cmdline_cpumask)) + cpumask_and(wq_unbound_cpumask, wq_unbound_cpumask, &wq_cmdline_cpumask); + pwq_cache = KMEM_CACHE(pool_workqueue, SLAB_PANIC); /* initialize CPU pools */ @@ -6577,3 +6583,14 @@ void __warn_flushing_systemwide_wq(void) dump_stack(); } EXPORT_SYMBOL(__warn_flushing_systemwide_wq); + +static int __init workqueue_unbound_cpus_setup(char *str) +{ + if (cpulist_parse(str, &wq_cmdline_cpumask) < 0) { + cpumask_clear(&wq_cmdline_cpumask); + pr_warn("workqueue.unbound_cpus: incorrect CPU range, using default\n"); + } + + return 1; +} +__setup("workqueue.unbound_cpus=", workqueue_unbound_cpus_setup); -- 2.7.4