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Subject[PATCH 14/19] tracing/workqueue: add max execution time mesurement for per worklet
Date
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

It is useful for driver-developer and system administrator to
know which worklet runs how many time.

Change Log:
v1: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
add max execution time mesurement for per workqueue
v2: Zhao Lei <zhaolei@cn.fujitsu.com>
add max execution time mesurement for per worklet instead of workqueue

Output is like:
# CPU INSERTED EXECUTED M_EXECus TASKNAME:PID
# | | | | `-WORKFUNC
# | | | | |
0 905 973 events/0:5
0 1 1 37 |-reg_todo+0x0/0x41f
0 13 12 2033 |-rt_worker_func+0x0/0x219
0 49 48 3157 |-mce_work_fn+0x0/0x31
0 14 13 939 |-check_corruption+0x0/0x2a
0 707 706 3826 |-vmstat_update+0x0/0x33
0 1 1 1846 |-power_supply_changed_work+0x0/0x3c
0 11 11 2879 |-console_callback+0x0/0xe1
0 30 29 1579 |-do_cache_clean+0x0/0x37
0 74 74 2841 |-test_work+0x0/0x53
0 3 2 252 |-rekey_seq_generator+0x0/0x5a
0 1 1 21 |-grace_ender+0x0/0x14
0 1 1 3701 `-flush_to_ldisc+0x0/0x15d
0 0 0 cpuset:6
0 658 658 khelper:7
0 658 658 5735 `-__call_usermodehelper+0x0/0x77
0 0 0 netns:11
...
[ Impact: provide per-worklet latency measurement ]

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
kernel/trace/trace_workqueue.c | 83 +++++++++++++++++++++++++++++++++------
1 files changed, 70 insertions(+), 13 deletions(-)
diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index b995bc0..798a738 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -24,6 +24,17 @@ struct workfunc_stats {
/* Protected by cpu workqueue lock */
unsigned int inserted;
unsigned int executed;
+
+ /*
+ * save latest work_struct's pointer to use as identifier in
+ * probe_worklet_complete, because we can't use work_struct->...
+ * after worklet got executed
+ */
+ void *work;
+
+ /* save execution time temporarily for calculate executed time */
+ u64 start_time;
+ u64 max_executed_time;
};

/* A cpu workqueue thread */
@@ -143,6 +154,8 @@ found_wq:
list_for_each_entry(wfnode, &node->workfunclist, list)
if (wfnode->func == work->func) {
wfnode->executed++;
+ wfnode->start_time = trace_clock_global();
+ wfnode->work = work;
goto found_wf;
}
pr_debug("trace_workqueue: worklet not found\n");
@@ -153,6 +166,43 @@ end:
spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
}

+/* Complete of a work */
+static void
+probe_worklet_complete(struct task_struct *wq_thread, void *work)
+{
+ int cpu = cpumask_first(&wq_thread->cpus_allowed);
+ struct cpu_workqueue_stats *node;
+ struct workfunc_stats *wfnode;
+ unsigned long flags;
+
+ spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
+
+ list_for_each_entry(node, &workqueue_cpu_stat(cpu)->list, list)
+ if (node->task == wq_thread)
+ goto found_wq;
+ pr_debug("trace_workqueue: workqueue not found\n");
+ goto end;
+
+found_wq:
+ list_for_each_entry(wfnode, &node->workfunclist, list) {
+ u64 executed_time;
+
+ if (wfnode->work != work)
+ continue;
+
+ executed_time = trace_clock_global() - wfnode->start_time;
+ if (executed_time > wfnode->max_executed_time)
+ wfnode->max_executed_time = executed_time;
+ goto found_wf;
+ }
+ pr_debug("trace_workqueue: worklet not found\n");
+ goto end;
+
+found_wf:
+end:
+ spin_unlock_irqrestore(&workqueue_cpu_stat(cpu)->lock, flags);
+}
+
/* Creation of a cpu workqueue thread */
static void probe_workqueue_creation(struct task_struct *wq_thread, int cpu)
{
@@ -316,7 +366,7 @@ static int workqueue_stat_show(struct seq_file *s, void *p)

if (!wfstat->func) {
/* It is first dummy node, need to print workqueue info */
- seq_printf(s, "%3d %6d %6u %s:%d\n",
+ seq_printf(s, " %3d %6d %6u %s:%d\n",
cws->cpu,
cws->inserted,
cws->executed,
@@ -325,10 +375,11 @@ static int workqueue_stat_show(struct seq_file *s, void *p)
} else {
/* It is effect node, need to print workfunc info */
int lastwf = list_is_last(&wfstat->list, &cws->workfunclist);
- seq_printf(s, "%3d %6d %6u %c-%pF\n",
+ seq_printf(s, " %3d %6d %6u %6llu %c-%pF\n",
cws->cpu,
wfstat->inserted,
wfstat->executed,
+ ns2usecs(wfstat->max_executed_time),
lastwf ? '`' : '|',
wfstat->func);
}
@@ -338,9 +389,9 @@ static int workqueue_stat_show(struct seq_file *s, void *p)

static int workqueue_stat_headers(struct seq_file *s)
{
- seq_printf(s, "# CPU INSERTED EXECUTED TASKNAME:PID\n");
- seq_printf(s, "# | | | `-WORKFUNC\n");
- seq_printf(s, "# | | | |\n");
+ seq_printf(s, "# CPU INSERTED EXECUTED M_EXECus TASKNAME:PID\n");
+ seq_printf(s, "# | | | | `-WORKFUNC\n");
+ seq_printf(s, "# | | | | |\n");
return 0;
}

@@ -379,19 +430,23 @@ int __init trace_workqueue_early_init(void)
ret = register_trace_worklet_enqueue_delayed(
probe_worklet_enqueue_delayed);
if (ret)
- goto no_enqueue;
+ goto out_worklet_enqueue;

ret = register_trace_worklet_execute(probe_worklet_execute);
if (ret)
- goto no_enqueue_delayed;
+ goto out_worklet_enqueue_delayed;
+
+ ret = register_trace_worklet_complete(probe_worklet_complete);
+ if (ret)
+ goto out_worklet_execute;

ret = register_trace_workqueue_creation(probe_workqueue_creation);
if (ret)
- goto no_handler_entry;
+ goto out_worklet_complete;

ret = register_trace_workqueue_destruction(probe_workqueue_destruction);
if (ret)
- goto no_creation;
+ goto out_workqueue_creation;

for_each_possible_cpu(cpu) {
spin_lock_init(&workqueue_cpu_stat(cpu)->lock);
@@ -400,13 +455,15 @@ int __init trace_workqueue_early_init(void)

return 0;

-no_creation:
+out_workqueue_creation:
unregister_trace_workqueue_creation(probe_workqueue_creation);
-no_handler_entry:
+out_worklet_complete:
+ unregister_trace_worklet_complete(probe_worklet_complete);
+out_worklet_execute:
unregister_trace_worklet_execute(probe_worklet_execute);
-no_enqueue_delayed:
+out_worklet_enqueue_delayed:
unregister_trace_worklet_enqueue_delayed(probe_worklet_enqueue_delayed);
-no_enqueue:
+out_worklet_enqueue:
unregister_trace_worklet_enqueue(probe_worklet_enqueue);
out:
pr_warning("trace_workqueue: unable to trace workqueues\n");
--
1.6.2.3


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