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bda7bad62b
linux/fs/proc
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KAMEZAWA Hiroyuki bda7bad62b 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: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-03-23 16:58:42 -07:00
..
array.c procfs: speed up /proc/pid/stat, statm 2012-03-23 16:58:42 -07:00
base.c procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
cmdline.c
consoles.c console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
cpuinfo.c
devices.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
generic.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
inode.c switch open-coded instances of d_make_root() to new helper 2012-03-20 21:29:35 -04:00
internal.h procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
interrupts.c
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
kcore.c fs/proc/kcore.c: make get_sparsemem_vmemmap_info() static 2012-03-23 16:58:42 -07:00
kmsg.c procfs: Use generic_file_llseek in /proc/kmsg 2010-04-09 16:35:41 +02:00
loadavg.c
Makefile ns: proc files for namespace naming policy. 2011-05-10 14:31:44 -07:00
meminfo.c fs/proc/meminfo.c: fix compilation error 2011-12-09 07:50:28 -08:00
mmu.c
namespaces.c vfs: trim includes a bit 2012-01-03 22:57:13 -05:00
nommu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page.c pagemap: export KPF_THP 2012-03-21 17:54:57 -07:00
proc_devtree.c of/flattree: Drop an uninteresting message to pr_debug level 2011-03-02 13:45:18 -07:00
proc_net.c switch procfs to umode_t use 2012-01-03 22:54:56 -05:00
proc_sysctl.c security: trim security.h 2012-02-14 10:45:42 +11:00
proc_tty.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
root.c procfs: add hidepid= and gid= mount options 2012-01-10 16:30:54 -08:00
softirqs.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
stat.c procfs: add num_to_str() to speed up /proc/stat 2012-03-23 16:58:42 -07:00
task_mmu.c procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
task_nommu.c procfs: mark thread stack correctly in proc/<pid>/maps 2012-03-21 17:54:58 -07:00
uptime.c Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip 2011-12-19 19:23:15 +01:00
version.c
vmcore.c fadump: Introduce cleanup routine to invalidate /proc/vmcore. 2012-02-23 10:50:02 +11:00