From d1be35cb6f96975d792a1535d3fe9b75239065ee Mon Sep 17 00:00:00 2001 From: Andrei Vagin Date: Tue, 10 Apr 2018 16:31:16 -0700 Subject: 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 Cc: Alexey Dobriyan Cc: KAMEZAWA Hiroyuki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/of/unittest.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'drivers/of') diff --git a/drivers/of/unittest.c b/drivers/of/unittest.c index 02c5984..6bb37c1 100644 --- a/drivers/of/unittest.c +++ b/drivers/of/unittest.c @@ -295,7 +295,7 @@ static void __init of_unittest_printf(void) return; } - num_to_str(phandle_str, sizeof(phandle_str), np->phandle); + num_to_str(phandle_str, sizeof(phandle_str), np->phandle, 0); of_unittest_printf_one(np, "%pOF", full_name); of_unittest_printf_one(np, "%pOFf", full_name); -- cgit v1.1