Re: Re: [PATCH 4/4] tracing/workqueue: Add max execution time mesurement for per worklet

[Zhaolei <zhaolei@cn.fujitsu.com>]

Oleg Nesterov wrote:
> I have no idea how the code actually looks with these patches applied,
> so please don't take my words seriously, but
> 
> On 04/28, Zhaolei wrote:
>> @@ -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;
> 
> Do we really need it ?
> 
>> @@ -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;
> 
> Perhaps we can add node->last_work (or whatever) instead? It should be
> recorded by the "entry" handler. In this case probe_worklet_complete()
> doesn't need to search for this work (and it doesn't need the argument).
> We know that wfnode == node->last_work.
Hello, Oleg

Sorry for reply late.

Thanks for review of this patch.
This is indeed a good idea, I will change to this way

Thanks
Zhaolei

> 
> Oleg.
> 
>