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Message-Id: <20081120210923.cfb90561.akpm@linux-foundation.org>
Date: Thu, 20 Nov 2008 21:09:23 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Keika Kobayashi <kobayashi.kk@...s.nec.co.jp>
Cc: linux-kernel@...r.kernel.org, h-shimamoto@...jp.nec.com,
Alexey Dobriyan <adobriyan@...il.com>
Subject: Re: [PATCH 2/3] proc: Export statistics for softirq to /proc
On Thu, 20 Nov 2008 19:58:43 -0800 Keika Kobayashi <kobayashi.kk@...s.nec.co.jp> wrote:
> Export statistics for softirq in /proc/softirqs and /proc/stat.
>
> 1. /proc/softirqs
> Implement /proc/softirqs which shows the number of softirq
> for each CPU like /proc/interrupts.
>
> 2. /proc/stat
> Add the "softirq" line to /proc/stat.
> This line shows the number of softirq for all cpu.
> The first column is the total of all softirqs and
> each subsequent column is the total for particular softirq.
>
> Signed-off-by: Keika Kobayashi <kobayashi.kk@...s.nec.co.jp>
> Reviewed-by: Hiroshi Shimamoto <h-shimamoto@...jp.nec.com>
This all looks reasonable to me.
> fs/proc/Makefile | 1 +
> fs/proc/softirqs.c | 57 +++++++++++++++++++++++++++++++++++++++++++++
> fs/proc/stat.c | 17 +++++++++++++
> include/linux/interrupt.h | 3 ++
> 4 files changed, 78 insertions(+), 0 deletions(-)
> create mode 100644 fs/proc/softirqs.c
>
> diff --git a/fs/proc/Makefile b/fs/proc/Makefile
> index 63d9651..11a7b5c 100644
> --- a/fs/proc/Makefile
> +++ b/fs/proc/Makefile
> @@ -18,6 +18,7 @@ proc-y += meminfo.o
> proc-y += stat.o
> proc-y += uptime.o
> proc-y += version.o
> +proc-y += softirqs.o
> proc-$(CONFIG_PROC_SYSCTL) += proc_sysctl.o
> proc-$(CONFIG_NET) += proc_net.o
> proc-$(CONFIG_PROC_KCORE) += kcore.o
> diff --git a/fs/proc/softirqs.c b/fs/proc/softirqs.c
> new file mode 100644
> index 0000000..43d3bc0
> --- /dev/null
> +++ b/fs/proc/softirqs.c
> @@ -0,0 +1,57 @@
> +#include <linux/init.h>
> +#include <linux/kernel_stat.h>
> +#include <linux/proc_fs.h>
> +#include <linux/seq_file.h>
> +
> +static const char *desc_array[] = {
> + "HI",
> + "TIMER",
> + "NET_TX",
> + "NET_RX",
> + "BLOCK",
> + "TASKLET",
> + "SCHED",
> +#ifdef CONFIG_HIGH_RES_TIMERS
> + "HRTIMER",
> +#endif
> + "RCU"};
> +
> +/*
> + * /proc/softirqs ... display the number of softirqs
> + */
> +static int show_softirqs(struct seq_file *p, void *v)
> +{
> + int i, j;
> +
> + seq_printf(p, " ");
> + for_each_online_cpu(i)
> + seq_printf(p, "CPU%-8d", i);
> + seq_printf(p, "\n");
> +
> + for_each_softirq_nr(i) {
> + seq_printf(p, "%-10s", desc_array[i]);
> + for_each_online_cpu(j)
> + seq_printf(p, "%10u ", kstat_softirqs_cpu(i, j));
> + seq_printf(p, "\n");
> + }
> + return 0;
> +}
This uses for_each_online_cpu(), but below we use for_each_possible_cpu().
Shouldn't we be consistent here so that at least the numbers will add
up to the same thing?
Probably for_each_possible_cpu() is best - people might want to see how
many softirqs happened on a CPU which was recently offlined.
> +
> +static int softirqs_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, show_softirqs, NULL);
> +}
> +
> +static struct file_operations proc_softirqs_operations = {
Make this const, please.
> + .open = softirqs_open,
> + .read = seq_read,
> + .llseek = seq_lseek,
> + .release = single_release,
> +};
> +
> +static int __init proc_softirqs_init(void)
> +{
> + proc_create("softirqs", 0, NULL, &proc_softirqs_operations);
> + return 0;
> +}
> +module_init(proc_softirqs_init);
> diff --git a/fs/proc/stat.c b/fs/proc/stat.c
> index 81904f0..02d5bf8 100644
> --- a/fs/proc/stat.c
> +++ b/fs/proc/stat.c
> @@ -25,6 +25,7 @@ static int show_stat(struct seq_file *p, void *v)
> cputime64_t user, nice, system, idle, iowait, irq, softirq, steal;
> cputime64_t guest;
> u64 sum = 0;
> + u64 sum_softirq = 0;
> struct timespec boottime;
> unsigned int per_irq_sum;
>
> @@ -49,6 +50,10 @@ static int show_stat(struct seq_file *p, void *v)
> sum += kstat_irqs_cpu(j, i);
>
> sum += arch_irq_stat_cpu(i);
> +
> + for_each_softirq_nr(j)
> + sum_softirq += kstat_softirqs_cpu(j, i);
> +
> }
> sum += arch_irq_stat();
>
> @@ -111,6 +116,18 @@ static int show_stat(struct seq_file *p, void *v)
> nr_running(),
> nr_iowait());
>
> + seq_printf(p, "softirq %llu", (unsigned long long)sum_softirq);
> +
> + for_each_softirq_nr(i) {
> + per_irq_sum = 0;
> +
> + for_each_possible_cpu(j)
> + per_irq_sum += kstat_softirqs_cpu(i, j);
> +
> + seq_printf(p, " %u", per_irq_sum);
> + }
> + seq_printf(p, "\n");
> +
> return 0;
> }
>
> diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
> index f58a0cf..9a12ba0 100644
> --- a/include/linux/interrupt.h
> +++ b/include/linux/interrupt.h
> @@ -259,6 +259,9 @@ enum
> NR_SOFTIRQS
> };
>
> +#define for_each_softirq_nr(irq) \
> + for (irq = 0; irq < NR_SOFTIRQS; irq++)
Can we remove this please? It doesn't make the code any more readable.
Just open-code the loop at each site.
(And strictly speaking the `irq' macro arg should be parenthesised)
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