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

[Frederic Weisbecker]

On Fri, Jan 16, 2009 at 04:32:25PM +0800, Lai Jiangshan wrote:
> 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@xxxxxxxxxxxxxx>
> ---


Thanks Lai!

Acked-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>

> 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;
> 

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