Messages in this thread Patch in this message | | | Date | Thu, 27 Jan 2022 14:23:26 -0300 | From | Marcelo Tosatti <> | Subject | [patch v9 07/10] task isolation: enable return to userspace processing |
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The logic to disable vmstat worker thread, when entering nohz full, does not cover all scenarios. For example, it is possible for the following to happen: References: <20220127172319.428529308@fuller.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8
Enable processing of pending task isolation work if per-CPU vmstats are out of sync with global vmstats.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
--- include/linux/task_isolation.h | 22 +++++++++++++++++++++- kernel/task_isolation.c | 13 +++++++++++++ 2 files changed, 34 insertions(+), 1 deletion(-)
Index: linux-2.6/include/linux/task_isolation.h =================================================================== --- linux-2.6.orig/include/linux/task_isolation.h +++ linux-2.6/include/linux/task_isolation.h @@ -5,6 +5,9 @@ #ifdef CONFIG_CPU_ISOLATION +#include <linux/vmstat.h> +#include <uapi/linux/prctl.h> + struct task_isol_info { /* Which features have been configured */ u64 conf_mask; @@ -110,7 +113,24 @@ static inline int prctl_task_isol_activa static inline int task_isol_has_work(void) { - return 0; + int cpu, ret; + struct isol_info *i; + + if (likely(current->task_isol_info == NULL)) + return 0; + + i = current->task_isol_info; + if (i->active_mask != ISOL_F_QUIESCE) + return 0; + + if (!(i->quiesce_mask & ISOL_F_QUIESCE_VMSTATS)) + return 0; + + cpu = get_cpu(); + ret = per_cpu(vmstat_dirty, cpu); + put_cpu(); + + return ret; } #endif /* CONFIG_CPU_ISOLATION */ Index: linux-2.6/kernel/task_isolation.c =================================================================== --- linux-2.6.orig/kernel/task_isolation.c +++ linux-2.6/kernel/task_isolation.c @@ -10,7 +10,6 @@ */ #include <linux/sched.h> -#include <linux/task_isolation.h> #include <linux/prctl.h> #include <linux/slab.h> #include <linux/kobject.h> @@ -20,9 +19,17 @@ #include <linux/sched/task.h> #include <linux/mm.h> #include <linux/vmstat.h> +#include <linux/task_isolation.h> void __task_isol_exit(struct task_struct *tsk) { + struct task_isol_info *i; + + i = tsk->task_isol_info; + if (!i) + return; + + static_key_slow_dec(&vmstat_sync_enabled); } void __task_isol_free(struct task_struct *tsk) @@ -41,6 +48,12 @@ static struct task_isol_info *task_isol_ if (unlikely(!info)) return ERR_PTR(-ENOMEM); + preempt_disable(); + init_sync_vmstat(); + preempt_enable(); + + static_key_slow_inc(&vmstat_sync_enabled); + return info; }
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