Re: [PATCH V4 13/15] blk-throttle: add a mechanism to estimate IO latency

From: kbuild test robot
Date: Mon Nov 14 2016 - 22:58:17 EST


Hi Shaohua,

[auto build test WARNING on linus/master]
[also build test WARNING on v4.9-rc5]
[cannot apply to block/for-next next-20161114]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url: https://github.com/0day-ci/linux/commits/Shaohua-Li/blk-throttle-add-high-limit/20161115-063105
config: openrisc-allyesconfig (attached as .config)
compiler: or32-linux-gcc (GCC) 4.5.1-or32-1.0rc1
reproduce:
wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
make.cross ARCH=openrisc

All warnings (new ones prefixed by >>):

block/blk-throttle.c: In function 'throtl_calculate_line_slope':
>> block/blk-throttle.c:2017:2: warning: comparison of distinct pointer types lacks a cast
block/blk-throttle.c:2019:2: warning: comparison of distinct pointer types lacks a cast
block/blk-throttle.c:2023:2: warning: comparison of distinct pointer types lacks a cast

vim +2017 block/blk-throttle.c

2001 for (i = 0; i < LATENCY_BUCKET_SIZE; i++) {
2002 u64 x, y;
2003
2004 if (td->avg_buckets[i].latency == 0)
2005 continue;
2006
2007 x = td->avg_buckets[i].size >> 10;
2008 y = td->avg_buckets[i].latency;
2009 sumX += x;
2010 sumY += y;
2011
2012 sumXY += x * y;
2013 sumX2 += x * x;
2014 }
2015
2016 xMean = sumX;
> 2017 do_div(xMean, valid_lat);
2018 yMean = sumY;
2019 do_div(yMean, valid_lat);
2020 denominator = sumX2 - sumX * xMean;
2021
2022 slope = sumXY - sumX * yMean;
2023 do_div(slope, denominator);
2024 td->line_slope = slope;
2025 }

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