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Subject[PATCH] tracing/workqueue: Get rid of searching last executed worklet in probe_worklet_complete()
We don't need search workqueue's worklet list for worklet which was latest
executed, instead, we can use a pointer in cpu_workqueue_stats to remember
which worklet was just executed.

Thanks Oleg for pointing it out.

Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
---
kernel/trace/trace_workqueue.c | 37 +++++++++++++------------------------
1 files changed, 13 insertions(+), 24 deletions(-)
diff --git a/kernel/trace/trace_workqueue.c b/kernel/trace/trace_workqueue.c
index c67be60..d90f9ac 100644
--- a/kernel/trace/trace_workqueue.c
+++ b/kernel/trace/trace_workqueue.c
@@ -25,13 +25,6 @@ struct workfunc_stats {
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;
@@ -46,10 +39,17 @@ struct cpu_workqueue_stats {
/* Protected by cpu workqueue lock */
unsigned int inserted;
unsigned int executed;
+
/* list of struct workfunc_stats in this workqueue */
struct list_head workfunclist;

/*
+ * pointer to last executed worklet's workfunc_stats in this workqueue,
+ * used by probe_worklet_complete()
+ */
+ struct workfunc_stats *last_workfunc;
+
+ /*
* the task maybe destroyed when we read stat file
* we define it to void * because we only use it as a identifier
*/
@@ -163,7 +163,7 @@ found_wq:
if (wfnode->func == work->func) {
wfnode->executed++;
wfnode->start_time = trace_clock_global();
- wfnode->work = work;
+ node->last_workfunc = wfnode;
goto found_wf;
}
pr_debug("trace_workqueue: worklet not found\n");
@@ -180,7 +180,7 @@ 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;
+ u64 executed_time;
unsigned long flags;

spin_lock_irqsave(&workqueue_cpu_stat(cpu)->lock, flags);
@@ -192,22 +192,11 @@ probe_worklet_complete(struct task_struct *wq_thread, void *work)
goto end;

found_wq:
- list_for_each_entry(wfnode, &node->workfunclist, list) {
- u64 executed_time;
+ executed_time = trace_clock_global() - node->last_workfunc->start_time;
+ node->last_workfunc->total_time += executed_time;
+ if (executed_time > node->last_workfunc->max_executed_time)
+ node->last_workfunc->max_executed_time = executed_time;

- if (wfnode->work != work)
- continue;
-
- executed_time = trace_clock_global() - wfnode->start_time;
- wfnode->total_time += executed_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);
}
--
1.5.5.3



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