Hi Dongdong, Thank you for the patch! Yet something to improve: [auto build test ERROR on linus/master] [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] url: https://github.com/0day-ci/linux/commits/Dongdong-Tao/bcache-consider-the-fragmentation-when-update-the-writeback-rate/20210105-110903 base: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git e71ba9452f0b5b2e8dc8aa5445198cd9214a6a62 config: i386-randconfig-a002-20200806 (attached as .config) compiler: gcc-9 (Debian 9.3.0-15) 9.3.0 reproduce (this is a W=1 build): # https://github.com/0day-ci/linux/commit/7777fef68d1401235db42dd0d59c5c3dba3d42d3 git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Dongdong-Tao/bcache-consider-the-fragmentation-when-update-the-writeback-rate/20210105-110903 git checkout 7777fef68d1401235db42dd0d59c5c3dba3d42d3 # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@xxxxxxxxx> All errors (new ones prefixed by >>): ld: drivers/md/bcache/writeback.o: in function `__update_writeback_rate': >> drivers/md/bcache/writeback.c:106: undefined reference to `__divdi3' >> ld: drivers/md/bcache/writeback.c:120: undefined reference to `__divdi3' vim +106 drivers/md/bcache/writeback.c 60 61 static void __update_writeback_rate(struct cached_dev *dc) 62 { 63 /* 64 * PI controller: 65 * Figures out the amount that should be written per second. 66 * 67 * First, the error (number of sectors that are dirty beyond our 68 * target) is calculated. The error is accumulated (numerically 69 * integrated). 70 * 71 * Then, the proportional value and integral value are scaled 72 * based on configured values. These are stored as inverses to 73 * avoid fixed point math and to make configuration easy-- e.g. 74 * the default value of 40 for writeback_rate_p_term_inverse 75 * attempts to write at a rate that would retire all the dirty 76 * blocks in 40 seconds. 77 * 78 * The writeback_rate_i_inverse value of 10000 means that 1/10000th 79 * of the error is accumulated in the integral term per second. 80 * This acts as a slow, long-term average that is not subject to 81 * variations in usage like the p term. 82 */ 83 int64_t target = __calc_target_rate(dc); 84 int64_t dirty = bcache_dev_sectors_dirty(&dc->disk); 85 int64_t error = dirty - target; 86 int64_t proportional_scaled = 87 div_s64(error, dc->writeback_rate_p_term_inverse); 88 int64_t integral_scaled; 89 uint32_t new_rate; 90 91 /* 92 * We need to consider the number of dirty buckets as well 93 * when calculating the proportional_scaled, Otherwise we might 94 * have an unreasonable small writeback rate at a highly fragmented situation 95 * when very few dirty sectors consumed a lot dirty buckets, the 96 * worst case is when dirty_data reached writeback_percent and 97 * dirty buckets reached to cutoff_writeback_sync, but the rate 98 * still will be at the minimum value, which will cause the write 99 * stuck at a non-writeback mode. 100 */ 101 struct cache_set *c = dc->disk.c; 102 103 int64_t dirty_buckets = c->nbuckets - c->avail_nbuckets; 104 105 if (c->gc_stats.in_use > BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW && dirty > 0) { > 106 int64_t fragment = (dirty_buckets * c->cache->sb.bucket_size) / dirty; 107 int64_t fp_term; 108 int64_t fps; 109 110 if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID) { 111 fp_term = dc->writeback_rate_fp_term_low * 112 (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_LOW); 113 } else if (c->gc_stats.in_use <= BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH) { 114 fp_term = dc->writeback_rate_fp_term_mid * 115 (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_MID); 116 } else { 117 fp_term = dc->writeback_rate_fp_term_high * 118 (c->gc_stats.in_use - BCH_WRITEBACK_FRAGMENT_THRESHOLD_HIGH); 119 } > 120 fps = (dirty / dirty_buckets) * fp_term; 121 if (fragment > 3 && fps > proportional_scaled) { 122 //Only overrite the p when fragment > 3 123 proportional_scaled = fps; 124 } 125 } 126 127 if ((error < 0 && dc->writeback_rate_integral > 0) || 128 (error > 0 && time_before64(local_clock(), 129 dc->writeback_rate.next + NSEC_PER_MSEC))) { 130 /* 131 * Only decrease the integral term if it's more than 132 * zero. Only increase the integral term if the device 133 * is keeping up. (Don't wind up the integral 134 * ineffectively in either case). 135 * 136 * It's necessary to scale this by 137 * writeback_rate_update_seconds to keep the integral 138 * term dimensioned properly. 139 */ 140 dc->writeback_rate_integral += error * 141 dc->writeback_rate_update_seconds; 142 } 143 144 integral_scaled = div_s64(dc->writeback_rate_integral, 145 dc->writeback_rate_i_term_inverse); 146 147 new_rate = clamp_t(int32_t, (proportional_scaled + integral_scaled), 148 dc->writeback_rate_minimum, NSEC_PER_SEC); 149 150 dc->writeback_rate_proportional = proportional_scaled; 151 dc->writeback_rate_integral_scaled = integral_scaled; 152 dc->writeback_rate_change = new_rate - 153 atomic_long_read(&dc->writeback_rate.rate); 154 atomic_long_set(&dc->writeback_rate.rate, new_rate); 155 dc->writeback_rate_target = target; 156 } 157 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx
Attachment:
.config.gz
Description: application/gzip
