| Message ID | 20230530145335.930262644@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | vmstat bug fixes for nohz_full CPUs | expand |
On Tue, 30 May 2023 11:52:37 -0300 Marcelo Tosatti <mtosatti@redhat.com> wrote: > Add a schedule_on_each_cpumask function, equivalent to > schedule_on_each_cpu but accepting a cpumask to operate. > > Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> > > --- > > Index: linux-vmstat-remote/kernel/workqueue.c > =================================================================== > --- linux-vmstat-remote.orig/kernel/workqueue.c > +++ linux-vmstat-remote/kernel/workqueue.c > @@ -3455,6 +3455,56 @@ int schedule_on_each_cpu(work_func_t fun > return 0; > } > > + > +/** > + * schedule_on_each_cpumask - execute a function synchronously on each > + * CPU in "cpumask", for those which are online. > + * > + * @func: the function to call > + * @mask: the CPUs which to call function on > + * > + * schedule_on_each_cpu() executes @func on each specified CPU that is online, > + * using the system workqueue and blocks until all such CPUs have completed. > + * schedule_on_each_cpu() is very slow. > + * > + * Return: > + * 0 on success, -errno on failure. > + */ > +int schedule_on_each_cpumask(work_func_t func, cpumask_t *cpumask) > +{ > + int cpu; > + struct work_struct __percpu *works; > + cpumask_var_t effmask; > + > + works = alloc_percpu(struct work_struct); > + if (!works) > + return -ENOMEM; > + > + if (!alloc_cpumask_var(&effmask, GFP_KERNEL)) { > + free_percpu(works); > + return -ENOMEM; > + } > + > + cpumask_and(effmask, cpumask, cpu_online_mask); > + > + cpus_read_lock(); > + > + for_each_cpu(cpu, effmask) { Should we check here that the cpu is still online? > + struct work_struct *work = per_cpu_ptr(works, cpu); > + > + INIT_WORK(work, func); > + schedule_work_on(cpu, work); > + } > + > + for_each_cpu(cpu, effmask) > + flush_work(per_cpu_ptr(works, cpu)); > + > + cpus_read_unlock(); > + free_percpu(works); > + free_cpumask_var(effmask); > + return 0; > +} > + > /** > * execute_in_process_context - reliably execute the routine with user context > * @fn: the function to execute > --- linux-vmstat-remote.orig/include/linux/workqueue.h > +++ linux-vmstat-remote/include/linux/workqueue.h > @@ -450,6 +450,7 @@ extern void __flush_workqueue(struct wor > extern void drain_workqueue(struct workqueue_struct *wq); > > extern int schedule_on_each_cpu(work_func_t func); > +extern int schedule_on_each_cpumask(work_func_t func, cpumask_t *cpumask); May as well make schedule_on_each_cpu() call schedule_on_each_cpumask()? Save a bit of text, and they're hardly performance-critical to that extent.
Index: linux-vmstat-remote/kernel/workqueue.c =================================================================== --- linux-vmstat-remote.orig/kernel/workqueue.c +++ linux-vmstat-remote/kernel/workqueue.c @@ -3455,6 +3455,56 @@ int schedule_on_each_cpu(work_func_t fun return 0; } + +/** + * schedule_on_each_cpumask - execute a function synchronously on each + * CPU in "cpumask", for those which are online. + * + * @func: the function to call + * @mask: the CPUs which to call function on + * + * schedule_on_each_cpu() executes @func on each specified CPU that is online, + * using the system workqueue and blocks until all such CPUs have completed. + * schedule_on_each_cpu() is very slow. + * + * Return: + * 0 on success, -errno on failure. + */ +int schedule_on_each_cpumask(work_func_t func, cpumask_t *cpumask) +{ + int cpu; + struct work_struct __percpu *works; + cpumask_var_t effmask; + + works = alloc_percpu(struct work_struct); + if (!works) + return -ENOMEM; + + if (!alloc_cpumask_var(&effmask, GFP_KERNEL)) { + free_percpu(works); + return -ENOMEM; + } + + cpumask_and(effmask, cpumask, cpu_online_mask); + + cpus_read_lock(); + + for_each_cpu(cpu, effmask) { + struct work_struct *work = per_cpu_ptr(works, cpu); + + INIT_WORK(work, func); + schedule_work_on(cpu, work); + } + + for_each_cpu(cpu, effmask) + flush_work(per_cpu_ptr(works, cpu)); + + cpus_read_unlock(); + free_percpu(works); + free_cpumask_var(effmask); + return 0; +} + /** * execute_in_process_context - reliably execute the routine with user context * @fn: the function to execute Index: linux-vmstat-remote/include/linux/workqueue.h =================================================================== --- linux-vmstat-remote.orig/include/linux/workqueue.h +++ linux-vmstat-remote/include/linux/workqueue.h @@ -450,6 +450,7 @@ extern void __flush_workqueue(struct wor extern void drain_workqueue(struct workqueue_struct *wq); extern int schedule_on_each_cpu(work_func_t func); +extern int schedule_on_each_cpumask(work_func_t func, cpumask_t *cpumask); int execute_in_process_context(work_func_t fn, struct execute_work *);
Add a schedule_on_each_cpumask function, equivalent to schedule_on_each_cpu but accepting a cpumask to operate. Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com> ---