From bda7bad62bc4c4e0783348e8db51abe094153c56 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Fri, 23 Mar 2012 15:02:54 -0700 Subject: procfs: speed up /proc/pid/stat, statm Process accounting applications as top, ps visit some files under /proc/. With seq_put_decimal_ull(), we can optimize /proc//stat and /proc//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 Cc: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/seq_file.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'include') diff --git a/include/linux/seq_file.h b/include/linux/seq_file.h index 5bba42c99448..54e5ae7f8adc 100644 --- a/include/linux/seq_file.h +++ b/include/linux/seq_file.h @@ -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) /* -- cgit v1.2.3