Re: [PATCH -tip] trace_workqueue: use percpu data for workqueue stat

Lai Jiangshan
2009-01-16T08:33:47Z

Impact: use percpu data instead hardcode

Use
static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
instead of allocate it.

And percpu data works well on NUMA.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index f8118d3..4664990 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -8,6 +8,7 @@

#include <trace/workqueue.h>
#include <linux/list.h>
+#include <linux/percpu.h>
#include "trace_stat.h"
#include "trace.h"

@@ -37,7 +38,8 @@ struct workqueue_global_stats {
/* Don't need a global lock because allocated before the workqueues, and
* never freed.
*/
-static struct workqueue_global_stats *all_workqueue_stat;
+static DEFINE_PER_CPU(struct workqueue_global_stats, all_workqueue_stat);
+#define workqueue_cpu_stat(cpu) (&per_cpu(all_workqueue_stat, cpu))

/* Insertion of a work */
static void
@@ -48,8 +50,8 @@ probe_workqueue_insertion(struct task_struct *wq_thread,
struct cpu_workqueue_stats *node, *next;
unsigned long flags;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- list_for_each_entry_safe(node, next, &all_workqueue_stat[cpu].list,
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
list) {
if (node->pid == wq_thread->pid) {
atomic_inc(&node->inserted);
@@ -58,7 +60,7 @@ probe_workqueue_insertion(struct task_struct *wq_thread,
}
pr_debug("trace_workqueue: entry not found\n");
found:
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}

/* Execution of a work */
@@ -70,8 +72,8 @@ probe_workqueue_execution(struct task_struct *wq_thread,
struct cpu_workqueue_stats *node, *next;
unsigned long flags;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- list_for_each_entry_safe(node, next, &all_workqueue_stat[cpu].list,
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
list) {
if (node->pid == wq_thread->pid) {
node->executed++;
@@ -80,7 +82,7 @@ probe_workqueue_execution(struct task_struct *wq_thread,
}
pr_debug("trace_workqueue: entry not found\n");
found:
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}

/* Creation of a cpu workqueue thread */
@@ -104,11 +106,11 @@ static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)

cws->pid = wq_thread->pid;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- if (list_empty(&all_workqueue_stat[cpu].list))
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ if (list_empty(&workqueue_cpu_stat(cpu)->list))
cws->first_entry = true;
- list_add_tail(&cws->list, &all_workqueue_stat[cpu].list);
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ list_add_tail(&cws->list, &workqueue_cpu_stat(cpu)->list);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}

/* Destruction of a cpu workqueue thread */
@@ -119,8 +121,8 @@ static void probe_workqueue_destruction(struct task_struct *wq_thread)
struct cpu_workqueue_stats *node, *next;
unsigned long flags;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- list_for_each_entry_safe(node, next, &all_workqueue_stat[cpu].list,
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ list_for_each_entry_safe(node, next, &workqueue_cpu_stat(cpu)->list,
list) {
if (node->pid == wq_thread->pid) {
list_del(&node->list);
@@ -131,7 +133,7 @@ static void probe_workqueue_destruction(struct task_struct *wq_thread)

pr_debug("trace_workqueue: don't find workqueue to destroy\n");
found:
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

}

@@ -141,13 +143,13 @@ static struct cpu_workqueue_stats *workqueue_stat_start_cpu(int cpu)
struct cpu_workqueue_stats *ret = NULL;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);

- if (!list_empty(&all_workqueue_stat[cpu].list))
- ret = list_entry(all_workqueue_stat[cpu].list.next,
+ if (!list_empty(&workqueue_cpu_stat(cpu)->list))
+ ret = list_entry(workqueue_cpu_stat(cpu)->list.next,
struct cpu_workqueue_stats, list);

- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

return ret;
}
@@ -172,9 +174,9 @@ static void *workqueue_stat_next(void *prev, int idx)
unsigned long flags;
void *ret = NULL;

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- if (list_is_last(&prev_cws->list, &all_workqueue_stat[cpu].list)) {
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ if (list_is_last(&prev_cws->list, &workqueue_cpu_stat(cpu)->list)) {
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
for (++cpu ; cpu < num_possible_cpus(); cpu++) {
ret = workqueue_stat_start_cpu(cpu);
if (ret)
@@ -182,7 +184,7 @@ static void *workqueue_stat_next(void *prev, int idx)
}
return NULL;
}
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

return list_entry(prev_cws->list.next, struct cpu_workqueue_stats,
list);
@@ -199,10 +201,10 @@ static int workqueue_stat_show(struct seq_file *s, void *p)
cws->executed,
trace_find_cmdline(cws->pid));

- spin_lock_irqsave(&all_workqueue_stat[cpu].lock, flags);
- if (&cws->list == all_workqueue_stat[cpu].list.next)
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+ if (&cws->list == workqueue_cpu_stat(cpu)->list.next)
seq_printf(s, "\n");
- spin_unlock_irqrestore(&all_workqueue_stat[cpu].lock, flags);
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);

return 0;
}
@@ -258,17 +260,9 @@ int __init trace_workqueue_early_init(void)
if (ret)
goto no_creation;

- all_workqueue_stat = kmalloc(sizeof(struct workqueue_global_stats)
- * num_possible_cpus(), GFP_KERNEL);
-
- if (!all_workqueue_stat) {
- pr_warning("trace_workqueue: not enough memory\n");
- goto no_creation;
- }
-
for_each_possible_cpu(cpu) {
- spin_lock_init(&all_workqueue_stat[cpu].lock);
- INIT_LIST_HEAD(&all_workqueue_stat[cpu].list);
+ spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
+ INIT_LIST_HEAD(&workqueue_cpu_stat(cpu)->list);
}

return 0;