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From:   Alexey Dobriyan <adobriyan@gmail.com>
To:     akpm@linux-foundation.org
Cc:     adobriyan@gmail.com, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org, pmladek@suse.com,
        rostedt@goodmis.org, sergey.senozhatsky@gmail.com,
        andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk
Subject: [PATCH 07/15] print_integer, proc: rewrite /proc/stat via print_integer()
Date:   Mon, 20 Apr 2020 23:57:35 +0300
Message-Id: <20200420205743.19964-7-adobriyan@gmail.com>
In-Reply-To: <20200420205743.19964-1-adobriyan@gmail.com>
References: <20200420205743.19964-1-adobriyan@gmail.com>
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Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---
 fs/proc/stat.c | 136 ++++++++++++++++++++++++++++++-------------------
 1 file changed, 83 insertions(+), 53 deletions(-)

diff --git a/fs/proc/stat.c b/fs/proc/stat.c
index 678feb7b9949..859dc49cca85 100644
--- a/fs/proc/stat.c
+++ b/fs/proc/stat.c
@@ -14,6 +14,8 @@
 #include <linux/sched/cputime.h>
 #include <linux/tick.h>
 
+#include "../../lib/print-integer.h"
+
 #ifndef arch_irq_stat_cpu
 #define arch_irq_stat_cpu(cpu) 0
 #endif
@@ -104,19 +106,30 @@ static void show_all_irqs(struct seq_file *p)
 	show_irq_gap(p, nr_irqs - next);
 }
 
+enum {
+	USER,
+	NICE,
+	SYSTEM,
+	IDLE,
+	IOWAIT,
+	IRQ,
+	SOFTIRQ,
+	STEAL,
+	GUEST,
+	GUEST_NICE,
+
+	NR_VAL
+};
+
 static int show_stat(struct seq_file *p, void *v)
 {
+	u64 val[NR_VAL] = {};
 	int i, j;
-	u64 user, nice, system, idle, iowait, irq, softirq, steal;
-	u64 guest, guest_nice;
 	u64 sum = 0;
 	u64 sum_softirq = 0;
 	unsigned int per_softirq_sums[NR_SOFTIRQS] = {0};
 	struct timespec64 boottime;
 
-	user = nice = system = idle = iowait =
-		irq = softirq = steal = 0;
-	guest = guest_nice = 0;
 	getboottime64(&boottime);
 
 	for_each_possible_cpu(i) {
@@ -125,16 +138,16 @@ static int show_stat(struct seq_file *p, void *v)
 
 		kcpustat_cpu_fetch(&kcpustat, i);
 
-		user		+= cpustat[CPUTIME_USER];
-		nice		+= cpustat[CPUTIME_NICE];
-		system		+= cpustat[CPUTIME_SYSTEM];
-		idle		+= get_idle_time(&kcpustat, i);
-		iowait		+= get_iowait_time(&kcpustat, i);
-		irq		+= cpustat[CPUTIME_IRQ];
-		softirq		+= cpustat[CPUTIME_SOFTIRQ];
-		steal		+= cpustat[CPUTIME_STEAL];
-		guest		+= cpustat[CPUTIME_GUEST];
-		guest_nice	+= cpustat[CPUTIME_GUEST_NICE];
+		val[USER]	+= cpustat[CPUTIME_USER];
+		val[NICE]	+= cpustat[CPUTIME_NICE];
+		val[SYSTEM]	+= cpustat[CPUTIME_SYSTEM];
+		val[IDLE]	+= get_idle_time(&kcpustat, i);
+		val[IOWAIT]	+= get_iowait_time(&kcpustat, i);
+		val[IRQ]	+= cpustat[CPUTIME_IRQ];
+		val[SOFTIRQ]	+= cpustat[CPUTIME_SOFTIRQ];
+		val[STEAL]	+= cpustat[CPUTIME_STEAL];
+		val[GUEST]	+= cpustat[CPUTIME_GUEST];
+		val[GUEST_NICE]	+= cpustat[CPUTIME_GUEST_NICE];
 		sum		+= kstat_cpu_irqs_sum(i);
 		sum		+= arch_irq_stat_cpu(i);
 
@@ -147,47 +160,55 @@ static int show_stat(struct seq_file *p, void *v)
 	}
 	sum += arch_irq_stat();
 
-	seq_put_decimal_ull(p, "cpu  ", nsec_to_clock_t(user));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(system));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(idle));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(iowait));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(irq));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(softirq));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(steal));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest));
-	seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
-	seq_putc(p, '\n');
+	{
+		char buf[4 + NR_VAL * (1 + 20) + 1];
+		char *q = buf + sizeof(buf);
+
+		*--q = '\n';
+		for (i = NR_VAL - 1; i >= 0; i--) {
+			q = _print_integer_u64(q, nsec_to_clock_t(val[i]));
+			*--q = ' ';
+		}
+		q = memcpy(q - 4, "cpu ", 4);
+
+		seq_write(p, q, buf + sizeof(buf) - q);
+	}
 
 	for_each_online_cpu(i) {
 		struct kernel_cpustat kcpustat;
 		u64 *cpustat = kcpustat.cpustat;
+		char buf[3 + 10 + NR_VAL * (1 + 20) + 1];
+		char *q = buf + sizeof(buf);
 
 		kcpustat_cpu_fetch(&kcpustat, i);
 
-		/* Copy values here to work around gcc-2.95.3, gcc-2.96 */
-		user		= cpustat[CPUTIME_USER];
-		nice		= cpustat[CPUTIME_NICE];
-		system		= cpustat[CPUTIME_SYSTEM];
-		idle		= get_idle_time(&kcpustat, i);
-		iowait		= get_iowait_time(&kcpustat, i);
-		irq		= cpustat[CPUTIME_IRQ];
-		softirq		= cpustat[CPUTIME_SOFTIRQ];
-		steal		= cpustat[CPUTIME_STEAL];
-		guest		= cpustat[CPUTIME_GUEST];
-		guest_nice	= cpustat[CPUTIME_GUEST_NICE];
-		seq_printf(p, "cpu%d", i);
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(user));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(nice));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(system));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(idle));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(iowait));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(irq));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(softirq));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(steal));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest));
-		seq_put_decimal_ull(p, " ", nsec_to_clock_t(guest_nice));
-		seq_putc(p, '\n');
+		*--q = '\n';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_GUEST_NICE]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_GUEST]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_STEAL]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_SOFTIRQ]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_IRQ]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_IRQ]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(get_iowait_time(&kcpustat, i)));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(get_idle_time(&kcpustat, i)));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_SYSTEM]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_NICE]));
+		*--q = ' ';
+		q = _print_integer_u64(q, nsec_to_clock_t(cpustat[CPUTIME_USER]));
+		*--q = ' ';
+		q = _print_integer_u32(q, i);
+		q = memcpy(q - 3, "cpu", 3);
+
+		seq_write(p, q, buf + sizeof(buf) - q);
 	}
 	seq_put_decimal_ull(p, "intr ", (unsigned long long)sum);
 
@@ -205,11 +226,20 @@ static int show_stat(struct seq_file *p, void *v)
 		nr_running(),
 		nr_iowait());
 
-	seq_put_decimal_ull(p, "softirq ", (unsigned long long)sum_softirq);
+	{
+		char buf[8 + 20 + (1 + 10) * NR_SOFTIRQS + 1];
+		char *q = buf + sizeof(buf);
 
-	for (i = 0; i < NR_SOFTIRQS; i++)
-		seq_put_decimal_ull(p, " ", per_softirq_sums[i]);
-	seq_putc(p, '\n');
+		*--q = '\n';
+		for (i = NR_SOFTIRQS - 1; i >= 0; i--) {
+			q = _print_integer_u32(q, per_softirq_sums[i]);
+			*--q = ' ';
+		}
+		q = _print_integer_u64(q, sum_softirq);
+		q = memcpy(q - 8, "softirq ", 8);
+
+		seq_write(p, q, buf + sizeof(buf) - q);
+	}
 
 	return 0;
 }
-- 
2.24.1