lkml.org 
[lkml]   [2020]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH] 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>
---

fs/proc/array.c | 39 +++++++++++++++++++++++----------------
1 file changed, 23 insertions(+), 16 deletions(-)

--- 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;
}

\
 
 \ /
  Last update: 2020-03-07 16:45    [W:0.032 / U:2.328 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site