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authorAlexey Dobriyan <adobriyan@gmail.com>2020-04-07 06:09:05 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-07 20:43:42 +0300
commit5c5ab9714c2225d50119e397c537ad5e568f268b (patch)
tree9a68b7a199b7b287098b3197850fbff446bdcfb5 /fs/proc/array.c
parentd919b33dafb3e222d23671b2bb06d119aede625f (diff)
downloadlinux-5c5ab9714c2225d50119e397c537ad5e568f268b.tar.xz
proc: speed up /proc/*/statm
top(1) reads all /proc/*/statm files but kernel threads will always have zeros. Print those zeroes directly without going through seq_put_decimal_ull(). Speed up reading /proc/2/statm (which is kthreadd) is like 3%. My system has more kernel threads than normal processes after booting KDE. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Link: http://lkml.kernel.org/r/20200307154435.GA2788@avx2 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/proc/array.c')
-rw-r--r--fs/proc/array.c39
1 files changed, 23 insertions, 16 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c
index 5efaf3708ec6..8e16f14bb05a 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -635,28 +635,35 @@ int proc_tgid_stat(struct seq_file *m, struct pid_namespace *ns,
int proc_pid_statm(struct seq_file *m, struct pid_namespace *ns,
struct pid *pid, struct task_struct *task)
{
- unsigned long size = 0, resident = 0, shared = 0, text = 0, data = 0;
struct mm_struct *mm = get_task_mm(task);
if (mm) {
+ unsigned long size;
+ unsigned long resident = 0;
+ unsigned long shared = 0;
+ unsigned long text = 0;
+ unsigned long data = 0;
+
size = task_statm(mm, &shared, &text, &data, &resident);
mmput(mm);
- }
- /*
- * 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, "", 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, " ", data);
- seq_put_decimal_ull(m, " ", 0);
- seq_putc(m, '\n');
+ /*
+ * 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, "", 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, " ", data);
+ seq_put_decimal_ull(m, " ", 0);
+ seq_putc(m, '\n');
+ } else {
+ seq_write(m, "0 0 0 0 0 0 0\n", 14);
+ }
return 0;
}