linux-kernel - Re: [PATCH v2 1/2] lib/find_bit_benchmark: Add benchmark test for fns()

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Date: Wed, 1 May 2024 06:50:25 +0800
From: kernel test robot <lkp@...el.com>
To: Kuan-Wei Chiu <visitorckw@...il.com>, akpm@...ux-foundation.org,
	yury.norov@...il.com
Cc: oe-kbuild-all@...ts.linux.dev, linux@...musvillemoes.dk,
	linux-kernel@...r.kernel.org, Kuan-Wei Chiu <visitorckw@...il.com>
Subject: Re: [PATCH v2 1/2] lib/find_bit_benchmark: Add benchmark test for
 fns()

Hi Kuan-Wei,

kernel test robot noticed the following build warnings:

[auto build test WARNING on linus/master]
[also build test WARNING on v6.9-rc6 next-20240430]
[cannot apply to akpm-mm/mm-everything akpm-mm/mm-nonmm-unstable]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Kuan-Wei-Chiu/lib-find_bit_benchmark-Add-benchmark-test-for-fns/20240430-144241
base:   linus/master
patch link:    https://lore.kernel.org/r/20240430054912.124237-2-visitorckw%40gmail.com
patch subject: [PATCH v2 1/2] lib/find_bit_benchmark: Add benchmark test for fns()
config: i386-buildonly-randconfig-004-20240501 (https://download.01.org/0day-ci/archive/20240501/202405010642.tHmTpd1i-lkp@intel.com/config)
compiler: gcc-11 (Ubuntu 11.4.0-4ubuntu1) 11.4.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240501/202405010642.tHmTpd1i-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@...el.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202405010642.tHmTpd1i-lkp@intel.com/

All warnings (new ones prefixed by >>):

   lib/find_bit_benchmark.c: In function 'test_fns':
>> lib/find_bit_benchmark.c:154:35: warning: variable 'y' set but not used [-Wunused-but-set-variable]
     154 |         volatile unsigned long x, y;
         |                                   ^


vim +/y +154 lib/find_bit_benchmark.c

   148	
   149	static int __init test_fns(void)
   150	{
   151		const unsigned long round = 1000000;
   152		s64 time[BITS_PER_LONG + 1];
   153		unsigned int i, n;
 > 154		volatile unsigned long x, y;
   155	
   156		for (n = 0; n <= BITS_PER_LONG; n++) {
   157			time[n] = ktime_get();
   158			for (i = 0; i < round; i++) {
   159				x = get_random_long();
   160				y = fns(x, n);
   161			}
   162			time[n] = ktime_get() - time[n];
   163		}
   164	
   165		for (n = 0; n <= BITS_PER_LONG; n++)
   166			pr_err("fns: n = %2u: %12lld ns\n", n, time[n]);
   167	
   168		return 0;
   169	}
   170	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki