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From: Andrea Righi <andrea@betterlinux.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Glauber Costa <glommer@parallels.com>,
	Peter Zijlstra <a.p.zijlstra@chello.nl>,
	Ingo Molnar <mingo@elte.hu>,
	linux-kernel@vger.kernel.org,
	Russell King - ARM Linux <linux@arm.linux.org.uk>,
	Paul Tuner <pjt@google.com>
Subject: Re: [PATCH] Add num_to_str() for speedup /proc/stat
Date: Wed, 1 Feb 2012 15:43:33 +0100	[thread overview]
Message-ID: <20120201144333.GA1542@thinkpad> (raw)
In-Reply-To: <20120130141619.a35863e2.kamezawa.hiroyu@jp.fujitsu.com>

On Mon, Jan 30, 2012 at 02:16:19PM +0900, KAMEZAWA Hiroyuki wrote:
...
> diff --git a/fs/proc/stat.c b/fs/proc/stat.c
> index 121f77c..0ff3b92 100644
> --- a/fs/proc/stat.c
> +++ b/fs/proc/stat.c
> @@ -89,18 +89,19 @@ static int show_stat(struct seq_file *p, void *v)
>  	}
>  	sum += arch_irq_stat();
>  
> -	seq_printf(p, "cpu  %llu %llu %llu %llu %llu %llu %llu %llu %llu "
> -		"%llu\n",
> -		(unsigned long long)cputime64_to_clock_t(user),
> -		(unsigned long long)cputime64_to_clock_t(nice),
> -		(unsigned long long)cputime64_to_clock_t(system),
> -		(unsigned long long)cputime64_to_clock_t(idle),
> -		(unsigned long long)cputime64_to_clock_t(iowait),
> -		(unsigned long long)cputime64_to_clock_t(irq),
> -		(unsigned long long)cputime64_to_clock_t(softirq),
> -		(unsigned long long)cputime64_to_clock_t(steal),
> -		(unsigned long long)cputime64_to_clock_t(guest),
> -		(unsigned long long)cputime64_to_clock_t(guest_nice));
> +	seq_puts(p, "cpu ");
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(user));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(nice));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(system));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(idle));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(iowait));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(irq));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(softirq));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(steal));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest));
> +	seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(guest_nice));
> +	seq_putc(p, '\n');
> +
>  	for_each_online_cpu(i) {
>  		/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
>  		user = kcpustat_cpu(i).cpustat[CPUTIME_USER];
> @@ -113,26 +114,24 @@ static int show_stat(struct seq_file *p, void *v)
>  		steal = kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
>  		guest = kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
>  		guest_nice = kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
> -		seq_printf(p,
> -			"cpu%d %llu %llu %llu %llu %llu %llu %llu %llu %llu "
> -			"%llu\n",
> -			i,
> -			(unsigned long long)cputime64_to_clock_t(user),
> -			(unsigned long long)cputime64_to_clock_t(nice),
> -			(unsigned long long)cputime64_to_clock_t(system),
> -			(unsigned long long)cputime64_to_clock_t(idle),
> -			(unsigned long long)cputime64_to_clock_t(iowait),
> -			(unsigned long long)cputime64_to_clock_t(irq),
> -			(unsigned long long)cputime64_to_clock_t(softirq),
> -			(unsigned long long)cputime64_to_clock_t(steal),
> -			(unsigned long long)cputime64_to_clock_t(guest),
> -			(unsigned long long)cputime64_to_clock_t(guest_nice));
> +		seq_printf(p, "cpu %d", i);
                               ^^^^^^
mmh... if I'm not wrong this looks like an ABI change.

Thanks,
-Andrea

---
From: Andrea Righi <andrea@betterlinux.com>
Subject: procfs: avoid breaking the ABI in /proc/stat

The speed up of /proc/stat changed the output of the cpu statistics
adding an extra space between the string "cpu" and the cpu id.

Restore the old ABI by removing this space.

Signed-off-by: Andrea Righi <andrea@betterlinux.com>
---
 fs/proc/stat.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 0ff3b92..7ed7efa 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -114,7 +114,7 @@ static int show_stat(struct seq_file *p, void *v)
 		steal = kcpustat_cpu(i).cpustat[CPUTIME_STEAL];
 		guest = kcpustat_cpu(i).cpustat[CPUTIME_GUEST];
 		guest_nice = kcpustat_cpu(i).cpustat[CPUTIME_GUEST_NICE];
-		seq_printf(p, "cpu %d", i);
+		seq_printf(p, "cpu%d", i);
 		seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(user));
 		seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(nice));
 		seq_put_decimal_ull(p, ' ', cputime64_to_clock_t(system));


  parent reply	other threads:[~2012-02-01 14:50 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-01-20 15:59 [PATCH] proc: speedup /proc/stat handling Eric Dumazet
2012-01-20 22:55 ` Andrew Morton
2012-01-23 10:16 ` KAMEZAWA Hiroyuki
2012-01-23 10:33   ` Glauber Costa
2012-01-24  1:25     ` KAMEZAWA Hiroyuki
2012-01-25  0:01 ` [PATCH v2] " Eric Dumazet
2012-01-25  0:12   ` Andrew Morton
2012-01-25  0:22     ` Eric Dumazet
2012-01-25  1:27       ` Andrew Morton
2012-01-25  5:29         ` Eric Dumazet
2012-01-26  1:04           ` Andrew Morton
2012-01-26  9:55             ` KAMEZAWA Hiroyuki
2012-01-27  0:43               ` Andrew Morton
2012-01-27  1:09                 ` KAMEZAWA Hiroyuki
2012-01-27  1:18                   ` Andrew Morton
2012-01-30  5:16                     ` [PATCH] Add num_to_str() for speedup /proc/stat KAMEZAWA Hiroyuki
2012-01-30 23:20                       ` Andrew Morton
2012-01-30 23:58                         ` KAMEZAWA Hiroyuki
2012-02-01 14:43                       ` Andrea Righi [this message]
2012-02-01 23:46                         ` KAMEZAWA Hiroyuki
2012-01-27  7:09                   ` [PATCH v2] proc: speedup /proc/stat handling Eric Dumazet
2012-01-25  0:18   ` KAMEZAWA Hiroyuki
2012-01-25  0:26     ` Eric Dumazet
2012-01-30  8:06       ` Jörg-Volker Peetz
2012-01-30  9:25         ` Eric Dumazet
2012-01-30 10:00           ` Jörg-Volker Peetz

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