lkml.org 
[lkml]   [2022]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[patch v9 07/10] task isolation: enable return to userspace processing
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;
}


\
 
 \ /
  Last update: 2022-01-27 18:26    [W:0.033 / U:0.276 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site