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Commit 4ba281d5 authored by Yury Norov's avatar Yury Norov Committed by Linus Torvalds
Browse files

lib/find_bit_benchmark.c: avoid soft lockup in test_find_first_bit() 

test_find_first_bit() is intentionally sub-optimal, and may cause soft
lockup due to long time of run on some systems.  So decrease length of
bitmap to traverse to avoid lockup.

With the change below, time of test execution doesn't exceed 0.2 seconds
on my testing system.

Link: http://lkml.kernel.org/r/20180420171949.15710-1-ynorov@caviumnetworks.com


Fixes: 4441fca0 ("lib: test module for find_*_bit() functions")
Signed-off-by: default avatarYury Norov <ynorov@caviumnetworks.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reported-by: default avatarFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c9cf87ea

lib/find_bit_benchmark.c

+6 −1
Original line number Diff line number Diff line
@@ -132,7 +132,12 @@ static int __init find_bit_test(void) 
	test_find_next_bit(bitmap, BITMAP_LEN);

	test_find_next_zero_bit(bitmap, BITMAP_LEN);

	test_find_last_bit(bitmap, BITMAP_LEN);

	test_find_first_bit(bitmap, BITMAP_LEN);



	/*

	 * test_find_first_bit() may take some time, so

	 * traverse only part of bitmap to avoid soft lockup.

	 */

	test_find_first_bit(bitmap, BITMAP_LEN / 10);

	test_find_next_and_bit(bitmap, bitmap2, BITMAP_LEN);



	pr_err("\nStart testing find_bit() with sparse bitmap\n");