Commit bda7bad6 authored by KAMEZAWA Hiroyuki's avatar KAMEZAWA Hiroyuki Committed by Linus Torvalds
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procfs: speed up /proc/pid/stat, statm 



Process accounting applications as top, ps visit some files under
/proc/<pid>.  With seq_put_decimal_ull(), we can optimize /proc/<pid>/stat
and /proc/<pid>/statm files.

This patch adds
  - seq_put_decimal_ll() for signed values.
  - allow delimiter == 0.
  - convert seq_printf() to seq_put_decimal_ull/ll in /proc/stat, statm.

Test result on a system with 2000+ procs.

Before patch:
  [kamezawa@bluextal test]$ top -b -n 1 | wc -l
  2223
  [kamezawa@bluextal test]$ time top -b -n 1 > /dev/null

  real    0m0.675s
  user    0m0.044s
  sys     0m0.121s

  [kamezawa@bluextal test]$ time ps -elf > /dev/null

  real    0m0.236s
  user    0m0.056s
  sys     0m0.176s

After patch:
  kamezawa@bluextal ~]$ time top -b -n 1 > /dev/null

  real    0m0.657s
  user    0m0.052s
  sys     0m0.100s

  [kamezawa@bluextal ~]$ time ps -elf > /dev/null

  real    0m0.198s
  user    0m0.050s
  sys     0m0.145s

Considering top, ps tend to scan /proc periodically, this will reduce cpu
consumption by top/ps to some extent.

[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: default avatarKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1ac101a5

fs/proc/array.c

+64 −55
Original line number Diff line number Diff line
@@ -462,59 +462,56 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns, 
	/* convert nsec -> ticks */

	start_time = nsec_to_clock_t(start_time);



	seq_printf(m, "%d (%s) %c %d %d %d %d %d %u %lu \

%lu %lu %lu %lu %lu %ld %ld %ld %ld %d 0 %llu %lu %ld %lu %lu %lu %lu %lu \

%lu %lu %lu %lu %lu %lu %lu %lu %d %d %u %u %llu %lu %ld %lu %lu %lu\n",

		pid_nr_ns(pid, ns),

		tcomm,

		state,

		ppid,

		pgid,

		sid,

		tty_nr,

		tty_pgrp,

		task->flags,

		min_flt,

		cmin_flt,

		maj_flt,

		cmaj_flt,

		cputime_to_clock_t(utime),

		cputime_to_clock_t(stime),

		cputime_to_clock_t(cutime),

		cputime_to_clock_t(cstime),

		priority,

		nice,

		num_threads,

		start_time,

		vsize,

		mm ? get_mm_rss(mm) : 0,

		rsslim,

		mm ? (permitted ? mm->start_code : 1) : 0,

		mm ? (permitted ? mm->end_code : 1) : 0,

		(permitted && mm) ? mm->start_stack : 0,

		esp,

		eip,

	seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state);

	seq_put_decimal_ll(m, ' ', ppid);

	seq_put_decimal_ll(m, ' ', pgid);

	seq_put_decimal_ll(m, ' ', sid);

	seq_put_decimal_ll(m, ' ', tty_nr);

	seq_put_decimal_ll(m, ' ', tty_pgrp);

	seq_put_decimal_ull(m, ' ', task->flags);

	seq_put_decimal_ull(m, ' ', min_flt);

	seq_put_decimal_ull(m, ' ', cmin_flt);

	seq_put_decimal_ull(m, ' ', maj_flt);

	seq_put_decimal_ull(m, ' ', cmaj_flt);

	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(utime));

	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(stime));

	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cutime));

	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cstime));

	seq_put_decimal_ll(m, ' ', priority);

	seq_put_decimal_ll(m, ' ', nice);

	seq_put_decimal_ll(m, ' ', num_threads);

	seq_put_decimal_ull(m, ' ', 0);

	seq_put_decimal_ull(m, ' ', start_time);

	seq_put_decimal_ull(m, ' ', vsize);

	seq_put_decimal_ll(m, ' ', mm ? get_mm_rss(mm) : 0);

	seq_put_decimal_ull(m, ' ', rsslim);

	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->start_code : 1) : 0);

	seq_put_decimal_ull(m, ' ', mm ? (permitted ? mm->end_code : 1) : 0);

	seq_put_decimal_ull(m, ' ', (permitted && mm) ? mm->start_stack : 0);

	seq_put_decimal_ull(m, ' ', esp);

	seq_put_decimal_ull(m, ' ', eip);

	/* The signal information here is obsolete.

	 * It must be decimal for Linux 2.0 compatibility.

	 * Use /proc/#/status for real-time signals.

	 */

		task->pending.signal.sig[0] & 0x7fffffffUL,

		task->blocked.sig[0] & 0x7fffffffUL,

		sigign      .sig[0] & 0x7fffffffUL,

		sigcatch    .sig[0] & 0x7fffffffUL,

		wchan,

		0UL,

		0UL,

		task->exit_signal,

		task_cpu(task),

		task->rt_priority,

		task->policy,

		(unsigned long long)delayacct_blkio_ticks(task),

		cputime_to_clock_t(gtime),

		cputime_to_clock_t(cgtime),

		(mm && permitted) ? mm->start_data : 0,

		(mm && permitted) ? mm->end_data : 0,

		(mm && permitted) ? mm->start_brk : 0);

	seq_put_decimal_ull(m, ' ', task->pending.signal.sig[0] & 0x7fffffffUL);

	seq_put_decimal_ull(m, ' ', task->blocked.sig[0] & 0x7fffffffUL);

	seq_put_decimal_ull(m, ' ', sigign.sig[0] & 0x7fffffffUL);

	seq_put_decimal_ull(m, ' ', sigcatch.sig[0] & 0x7fffffffUL);

	seq_put_decimal_ull(m, ' ', wchan);

	seq_put_decimal_ull(m, ' ', 0);

	seq_put_decimal_ull(m, ' ', 0);

	seq_put_decimal_ll(m, ' ', task->exit_signal);

	seq_put_decimal_ll(m, ' ', task_cpu(task));

	seq_put_decimal_ull(m, ' ', task->rt_priority);

	seq_put_decimal_ull(m, ' ', task->policy);

	seq_put_decimal_ull(m, ' ', delayacct_blkio_ticks(task));

	seq_put_decimal_ull(m, ' ', cputime_to_clock_t(gtime));

	seq_put_decimal_ll(m, ' ', cputime_to_clock_t(cgtime));

	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_data : 0);

	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->end_data : 0);

	seq_put_decimal_ull(m, ' ', (mm && permitted) ? mm->start_brk : 0);

	seq_putc(m, '\n');

	if (mm)

		mmput(mm);

	return 0;
@@ -542,8 +539,20 @@ int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns, 
		size = task_statm(mm, &shared, &text, &data, &resident);

		mmput(mm);

	}

	seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",

			size, resident, shared, text, data);

	/*

	 * For quick read, open code by putting numbers directly

	 * expected format is

	 * seq_printf(m, "%lu %lu %lu %lu 0 %lu 0\n",

	 *               size, resident, shared, text, data);

	 */

	seq_put_decimal_ull(m, 0, size);

	seq_put_decimal_ull(m, ' ', resident);

	seq_put_decimal_ull(m, ' ', shared);

	seq_put_decimal_ull(m, ' ', text);

	seq_put_decimal_ull(m, ' ', 0);

	seq_put_decimal_ull(m, ' ', text);

	seq_put_decimal_ull(m, ' ', 0);

	seq_putc(m, '\n');



	return 0;

}

fs/seq_file.c

+20 −1
Original line number Diff line number Diff line
@@ -659,6 +659,7 @@ int seq_put_decimal_ull(struct seq_file *m, char delimiter, 
	if (m->count + 2 >= m->size) /* we'll write 2 bytes at least */

		goto overflow;



	if (delimiter)

		m->buf[m->count++] = delimiter;



	if (num < 10) {
@@ -677,6 +678,24 @@ overflow: 
}

EXPORT_SYMBOL(seq_put_decimal_ull);



int seq_put_decimal_ll(struct seq_file *m, char delimiter,

			long long num)

{

	if (num < 0) {

		if (m->count + 3 >= m->size) {

			m->count = m->size;

			return -1;

		}

		if (delimiter)

			m->buf[m->count++] = delimiter;

		num = -num;

		delimiter = '-';

	}

	return seq_put_decimal_ull(m, delimiter, num);



}

EXPORT_SYMBOL(seq_put_decimal_ll);



/**

 * seq_write - write arbitrary data to buffer

 * @seq: seq_file identifying the buffer to which data should be written

include/linux/seq_file.h

+2 −0
Original line number Diff line number Diff line
@@ -123,6 +123,8 @@ int seq_open_private(struct file *, const struct seq_operations *, int); 
int seq_release_private(struct inode *, struct file *);

int seq_put_decimal_ull(struct seq_file *m, char delimiter,

			unsigned long long num);

int seq_put_decimal_ll(struct seq_file *m, char delimiter,

			long long num);



#define SEQ_START_TOKEN ((void *)1)

/*

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