]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commitdiff
proc: replace seq_printf by seq_put_smth to speed up /proc/pid/status
authorAndrei Vagin <avagin@openvz.org>
Tue, 10 Apr 2018 23:31:26 +0000 (16:31 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 11 Apr 2018 17:28:33 +0000 (10:28 -0700)
seq_printf() works slower than seq_puts, seq_puts, etc.

== test_proc.c
int main(int argc, char **argv)
{
int n, i, fd;
char buf[16384];

n = atoi(argv[1]);
for (i = 0; i < n; i++) {
fd = open(argv[2], O_RDONLY);
if (fd < 0)
return 1;
if (read(fd, buf, sizeof(buf)) <= 0)
return 1;
close(fd);
}

return 0;
}
==

$ time ./test_proc  1000000 /proc/1/status

== Before path ==
real 0m5.171s
user 0m0.328s
sys 0m4.783s

== After patch ==
real 0m4.761s
user 0m0.334s
sys 0m4.366s

Link: http://lkml.kernel.org/r/20180212074931.7227-4-avagin@openvz.org
Signed-off-by: Andrei Vagin <avagin@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/proc/array.c

index 851ec0915e4c2cc4d6d2dacb0ed6159a6eea7676..ae2c807fd719540312d18a94c7676ceb51b10f12 100644 (file)
@@ -174,7 +174,8 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
 
        if (umask >= 0)
                seq_printf(m, "Umask:\t%#04o\n", umask);
-       seq_printf(m, "State:\t%s", get_task_state(p));
+       seq_puts(m, "State:\t");
+       seq_puts(m, get_task_state(p));
 
        seq_put_decimal_ull(m, "\nTgid:\t", tgid);
        seq_put_decimal_ull(m, "\nNgid:\t", ngid);
@@ -300,8 +301,8 @@ static void render_cap_t(struct seq_file *m, const char *header,
 
        seq_puts(m, header);
        CAP_FOR_EACH_U32(__capi) {
-               seq_printf(m, "%08x",
-                          a->cap[CAP_LAST_U32 - __capi]);
+               seq_put_hex_ll(m, NULL,
+                          a->cap[CAP_LAST_U32 - __capi], 8);
        }
        seq_putc(m, '\n');
 }
@@ -355,7 +356,8 @@ static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
 
 static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)
 {
-       seq_printf(m, "CoreDumping:\t%d\n", !!mm->core_state);
+       seq_put_decimal_ull(m, "CoreDumping:\t", !!mm->core_state);
+       seq_putc(m, '\n');
 }
 
 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
@@ -491,7 +493,11 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
        /* convert nsec -> ticks */
        start_time = nsec_to_clock_t(task->real_start_time);
 
-       seq_printf(m, "%d (%s) %c", pid_nr_ns(pid, ns), tcomm, state);
+       seq_put_decimal_ull(m, "", pid_nr_ns(pid, ns));
+       seq_puts(m, " (");
+       seq_puts(m, tcomm);
+       seq_puts(m, ") ");
+       seq_putc(m, state);
        seq_put_decimal_ll(m, " ", ppid);
        seq_put_decimal_ll(m, " ", pgid);
        seq_put_decimal_ll(m, " ", sid);