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authorAndrei Vagin <avagin@openvz.org>2018-04-10 16:31:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:33 -0700
commitd1be35cb6f96975d792a1535d3fe9b75239065ee (patch)
tree42041a8e13b193af75214bd5286edb8ec0bdc167 /fs/seq_file.c
parent2acddbe8168967adebf4623923242c9a4f9e1aee (diff)
downloadlinux-stericsson-d1be35cb6f96975d792a1535d3fe9b75239065ee.tar.gz
proc: add seq_put_decimal_ull_width to speed up /proc/pid/smaps
seq_put_decimal_ull_w(m, str, val, width) prints a decimal number with a specified minimal field width. It is equivalent of seq_printf(m, "%s%*d", str, width, val), but it works much faster. == test_smaps.py num = 0 with open("/proc/1/smaps") as f: for x in xrange(10000): data = f.read() f.seek(0, 0) == == Before patch == $ time python test_smaps.py real 0m4.593s user 0m0.398s sys 0m4.158s == After patch == $ time python test_smaps.py real 0m3.828s user 0m0.413s sys 0m3.408s $ perf -g record python test_smaps.py == Before patch == - 79.01% 3.36% python [kernel.kallsyms] [k] show_smap.isra.33 - 75.65% show_smap.isra.33 + 48.85% seq_printf + 15.75% __walk_page_range + 9.70% show_map_vma.isra.23 0.61% seq_puts == After patch == - 75.51% 4.62% python [kernel.kallsyms] [k] show_smap.isra.33 - 70.88% show_smap.isra.33 + 24.82% seq_put_decimal_ull_w + 19.78% __walk_page_range + 12.74% seq_printf + 11.08% show_map_vma.isra.23 + 1.68% seq_puts [akpm@linux-foundation.org: fix drivers/of/unittest.c build] Link: http://lkml.kernel.org/r/20180212074931.7227-1-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>
Diffstat (limited to 'fs/seq_file.c')
-rw-r--r--fs/seq_file.c28
1 files changed, 21 insertions, 7 deletions
diff --git a/fs/seq_file.c b/fs/seq_file.c
index 3714ae1d5e1c..84650ad3b1bf 100644
--- a/fs/seq_file.c
+++ b/fs/seq_file.c
@@ -673,15 +673,20 @@ void seq_puts(struct seq_file *m, const char *s)
}
EXPORT_SYMBOL(seq_puts);
-/*
+/**
* A helper routine for putting decimal numbers without rich format of printf().
* only 'unsigned long long' is supported.
- * This routine will put strlen(delimiter) + number into seq_file.
+ * @m: seq_file identifying the buffer to which data should be written
+ * @delimiter: a string which is printed before the number
+ * @num: the number
+ * @width: a minimum field width
+ *
+ * This routine will put strlen(delimiter) + number into seq_filed.
* This routine is very quick when you show lots of numbers.
* In usual cases, it will be better to use seq_printf(). It's easier to read.
*/
-void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
- unsigned long long num)
+void seq_put_decimal_ull_width(struct seq_file *m, const char *delimiter,
+ unsigned long long num, unsigned int width)
{
int len;
@@ -695,7 +700,10 @@ void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
memcpy(m->buf + m->count, delimiter, len);
m->count += len;
- if (m->count + 1 >= m->size)
+ if (!width)
+ width = 1;
+
+ if (m->count + width >= m->size)
goto overflow;
if (num < 10) {
@@ -703,7 +711,7 @@ void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
return;
}
- len = num_to_str(m->buf + m->count, m->size - m->count, num);
+ len = num_to_str(m->buf + m->count, m->size - m->count, num, width);
if (!len)
goto overflow;
@@ -713,6 +721,12 @@ void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
overflow:
seq_set_overflow(m);
}
+
+void seq_put_decimal_ull(struct seq_file *m, const char *delimiter,
+ unsigned long long num)
+{
+ return seq_put_decimal_ull_width(m, delimiter, num, 0);
+}
EXPORT_SYMBOL(seq_put_decimal_ull);
/**
@@ -788,7 +802,7 @@ void seq_put_decimal_ll(struct seq_file *m, const char *delimiter, long long num
return;
}
- len = num_to_str(m->buf + m->count, m->size - m->count, num);
+ len = num_to_str(m->buf + m->count, m->size - m->count, num, 0);
if (!len)
goto overflow;