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Date: Sat, 22 Nov 2008 20:34:23 +0300
From: Alexey Dobriyan <adobriyan@gmail.com>
To: Joe Korty <joe.korty@ccur.com>
Cc: Ingo Molnar <mingo@elte.hu>, Thomas Gleixner <tglx@linutronix.de>,
       LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] create /proc/timer-wheel-list
Message-ID: <20081122173423.GC2748@x200.localdomain>
References: <20081121221113.GA13566@tsunami.ccur.com>
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On Fri, Nov 21, 2008 at 05:11:13PM -0500, Joe Korty wrote:
> Create /proc/timer_wheel_list.
> 
> This does for the timer wheel what /proc/timer_list
> does for hrtimers -- provide a way of displaying what
> timers are running on what cpus, and their attributes.

The fact that it's called a timer wheel is just an implementation detail
unsuitable for permanent file.

And you invented totally new (broken) way to print jiffies.

For printing nice function pointers we have %pF now.

late_initcall usage is taken out of air.

Can we put all this shit in debugfs, please?

> --- 2.6.28-rc6.orig/kernel/timer.c
> +++ 2.6.28-rc6/kernel/timer.c
> @@ -1568,6 +1570,113 @@
>  	open_softirq(TIMER_SOFTIRQ, run_timer_softirq);
>  }
>  
> +#ifdef CONFIG_PROC_FS
> +
> +static void seq_printf_symbol(struct seq_file *m, void *symaddr, int width)
> +{
> +	char symname[KSYM_NAME_LEN];
> +	int stat, len = m->count;
> +
> +	if (lookup_symbol_name((unsigned long)symaddr, symname) < 0)
> +		stat = seq_printf(m, "<%p>", symaddr);
> +	else
> +		stat = seq_printf(m, "%s", symname);
> +	if (width && stat == 0) {
> +		len += (width - m->count);
> +		if (len > 0)
> +			seq_printf(m, "%*s", len, " ");
> +	}
> +}
> +
> +static void print_single_timer(struct seq_file *m, struct timer_list *timer)
> +{
> +	unsigned long base_jiffies = tbase_get_base(timer->base)->timer_jiffies;
> +
> +	seq_printf(m, " %p - ", (void *)(timer->expires - base_jiffies));
> +	seq_printf_symbol(m, timer->function, 24);
> +	seq_printf(m, " (data ");
> +	seq_printf_symbol(m, (void *)(timer->data), 24);
> +	seq_printf(m, ")");
> +#ifdef CONFIG_TIMER_STATS
> +	seq_printf(m, " from ");
> +	seq_printf_symbol(m, timer->start_site, 28);
> +	seq_printf(m, " %*s/%d",
> +		TASK_COMM_LEN, timer->start_comm,
> +		timer->start_pid);
> +#endif
> +	seq_printf(m, "\n");
> +}
> +
> +static void print_timer_list(struct seq_file *m, struct list_head *head)
> +{
> +	struct timer_list *timer;
> +	struct list_head *item;
> +
> +	for (item = head->next; item != head; item = item->next) {
> +		timer = list_entry(item, struct timer_list, entry);
> +		print_single_timer(m, timer);
> +	}
> +}
> +
> +static void print_cpu_timers(struct seq_file *m, int cpu)
> +{
> +	int i;
> +	struct tvec_base *base = per_cpu(tvec_bases, cpu);
> +
> +	spin_lock_irq(&base->lock);
> +	seq_printf(m, "\ncpu: %d, base jiffies: %p\n\n",
> +		cpu, (void *)(base->timer_jiffies));
> +
> +	for (i = 0; i < TVR_SIZE; i++)
> +		print_timer_list(m, base->tv1.vec + i);
> +	for (i = 0; i < TVN_SIZE; i++) {
> +		print_timer_list(m, base->tv2.vec + i);
> +		print_timer_list(m, base->tv3.vec + i);
> +		print_timer_list(m, base->tv4.vec + i);
> +		print_timer_list(m, base->tv5.vec + i);
> +	}
> +	spin_unlock_irq(&base->lock);
> +}
> +
> +static int timer_list_show(struct seq_file *m, void *v)
> +{
> +	int cpu;
> +
> +	seq_printf(m, "Timer Wheel List Version: 1\n");
> +	seq_printf(m, "Jiffies: %px\n", (void *)jiffies);
> +
> +	for_each_online_cpu(cpu) {
> +		print_cpu_timers(m, cpu);
> +	}
> +
> +	return 0;
> +}
> +
> +static int timer_list_open(struct inode *inode, struct file *filp)
> +{
> +	return single_open(filp, timer_list_show, NULL);
> +}
> +
> +static struct file_operations timer_list_fops = {
> +	.open		= timer_list_open,
> +	.read		= seq_read,
> +	.llseek		= seq_lseek,
> +	.release	= single_release,
> +};
> +
> +static int __init init_timer_list_procfs(void)
> +{
> +	struct proc_dir_entry *pe;
> +
> +	pe = proc_create("timer_wheel_list", 0444, NULL, &timer_list_fops);
> +	if (!pe)
> +		return -ENOMEM;
> +	return 0;
> +}
> +late_initcall(init_timer_list_procfs);
> +
> +#endif /* CONFIG_PROC_FS */
--
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