2023-12-28 18:05:27

by Julia Lawall

[permalink] [raw]
Subject: drivers/gpu/drm/nouveau/nvkm/engine/gr/gv100.c:153:33-34: WARNING opportunity for max() (fwd)



---------- Forwarded message ----------
Date: Thu, 28 Dec 2023 19:36:08 +0800
From: kernel test robot <[email protected]>
To: [email protected]
Cc: [email protected], Julia Lawall <[email protected]>
Subject: drivers/gpu/drm/nouveau/nvkm/engine/gr/gv100.c:153:33-34: WARNING
opportunity for max()

BCC: [email protected]
CC: [email protected]
CC: [email protected]
TO: Ben Skeggs <[email protected]>
CC: Lyude Paul <[email protected]>

tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head: f5837722ffecbbedf1b1dbab072a063565f0dad1
commit: 3ffa6f329b610029b44ebd7bc2320a92468a0e42 drm/nouveau/gr/gv100-: port smid mapping code from nvgpu
date: 1 year, 2 months ago
:::::: branch date: 11 hours ago
:::::: commit date: 1 year, 2 months ago
config: loongarch-randconfig-r062-20231222 (https://download.01.org/0day-ci/archive/20231228/[email protected]/config)
compiler: loongarch64-linux-gcc (GCC) 13.2.0

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 <[email protected]>
| Reported-by: Julia Lawall <[email protected]>
| Closes: https://lore.kernel.org/r/[email protected]/

cocci warnings: (new ones prefixed by >>)
>> drivers/gpu/drm/nouveau/nvkm/engine/gr/gv100.c:153:33-34: WARNING opportunity for max()

vim +153 drivers/gpu/drm/nouveau/nvkm/engine/gr/gv100.c

3ffa6f329b6100 Ben Skeggs 2022-06-01 104
3ffa6f329b6100 Ben Skeggs 2022-06-01 105 static int
3ffa6f329b6100 Ben Skeggs 2022-06-01 106 gv100_gr_scg_estimate_perf(struct gf100_gr *gr, unsigned long *gpc_tpc_mask,
3ffa6f329b6100 Ben Skeggs 2022-06-01 107 u32 disable_gpc, u32 disable_tpc, int *perf)
3ffa6f329b6100 Ben Skeggs 2022-06-01 108 {
3ffa6f329b6100 Ben Skeggs 2022-06-01 109 const u32 scale_factor = 512UL; /* Use fx23.9 */
3ffa6f329b6100 Ben Skeggs 2022-06-01 110 const u32 pix_scale = 1024*1024UL; /* Pix perf in [29:20] */
3ffa6f329b6100 Ben Skeggs 2022-06-01 111 const u32 world_scale = 1024UL; /* World performance in [19:10] */
3ffa6f329b6100 Ben Skeggs 2022-06-01 112 const u32 tpc_scale = 1; /* TPC balancing in [9:0] */
3ffa6f329b6100 Ben Skeggs 2022-06-01 113 u32 scg_num_pes = 0;
3ffa6f329b6100 Ben Skeggs 2022-06-01 114 u32 min_scg_gpc_pix_perf = scale_factor; /* Init perf as maximum */
3ffa6f329b6100 Ben Skeggs 2022-06-01 115 u32 average_tpcs = 0; /* Average of # of TPCs per GPC */
3ffa6f329b6100 Ben Skeggs 2022-06-01 116 u32 deviation; /* absolute diff between TPC# and average_tpcs, averaged across GPCs */
3ffa6f329b6100 Ben Skeggs 2022-06-01 117 u32 norm_tpc_deviation; /* deviation/max_tpc_per_gpc */
3ffa6f329b6100 Ben Skeggs 2022-06-01 118 u32 tpc_balance;
3ffa6f329b6100 Ben Skeggs 2022-06-01 119 u32 scg_gpc_pix_perf;
3ffa6f329b6100 Ben Skeggs 2022-06-01 120 u32 scg_world_perf;
3ffa6f329b6100 Ben Skeggs 2022-06-01 121 u32 gpc;
3ffa6f329b6100 Ben Skeggs 2022-06-01 122 u32 pes;
3ffa6f329b6100 Ben Skeggs 2022-06-01 123 int diff;
3ffa6f329b6100 Ben Skeggs 2022-06-01 124 bool tpc_removed_gpc = false;
3ffa6f329b6100 Ben Skeggs 2022-06-01 125 bool tpc_removed_pes = false;
3ffa6f329b6100 Ben Skeggs 2022-06-01 126 u32 max_tpc_gpc = 0;
3ffa6f329b6100 Ben Skeggs 2022-06-01 127 u32 num_tpc_mask;
3ffa6f329b6100 Ben Skeggs 2022-06-01 128 u32 *num_tpc_gpc;
3ffa6f329b6100 Ben Skeggs 2022-06-01 129 int ret = -EINVAL;
3ffa6f329b6100 Ben Skeggs 2022-06-01 130
3ffa6f329b6100 Ben Skeggs 2022-06-01 131 if (!(num_tpc_gpc = kcalloc(gr->gpc_nr, sizeof(*num_tpc_gpc), GFP_KERNEL)))
3ffa6f329b6100 Ben Skeggs 2022-06-01 132 return -ENOMEM;
3ffa6f329b6100 Ben Skeggs 2022-06-01 133
3ffa6f329b6100 Ben Skeggs 2022-06-01 134 /* Calculate pix-perf-reduction-rate per GPC and find bottleneck TPC */
3ffa6f329b6100 Ben Skeggs 2022-06-01 135 for (gpc = 0; gpc < gr->gpc_nr; gpc++) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 136 num_tpc_mask = gpc_tpc_mask[gpc];
3ffa6f329b6100 Ben Skeggs 2022-06-01 137
3ffa6f329b6100 Ben Skeggs 2022-06-01 138 if ((gpc == disable_gpc) && num_tpc_mask & BIT(disable_tpc)) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 139 /* Safety check if a TPC is removed twice */
3ffa6f329b6100 Ben Skeggs 2022-06-01 140 if (WARN_ON(tpc_removed_gpc))
3ffa6f329b6100 Ben Skeggs 2022-06-01 141 goto done;
3ffa6f329b6100 Ben Skeggs 2022-06-01 142
3ffa6f329b6100 Ben Skeggs 2022-06-01 143 /* Remove logical TPC from set */
3ffa6f329b6100 Ben Skeggs 2022-06-01 144 num_tpc_mask &= ~BIT(disable_tpc);
3ffa6f329b6100 Ben Skeggs 2022-06-01 145 tpc_removed_gpc = true;
3ffa6f329b6100 Ben Skeggs 2022-06-01 146 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 147
3ffa6f329b6100 Ben Skeggs 2022-06-01 148 /* track balancing of tpcs across gpcs */
3ffa6f329b6100 Ben Skeggs 2022-06-01 149 num_tpc_gpc[gpc] = hweight32(num_tpc_mask);
3ffa6f329b6100 Ben Skeggs 2022-06-01 150 average_tpcs += num_tpc_gpc[gpc];
3ffa6f329b6100 Ben Skeggs 2022-06-01 151
3ffa6f329b6100 Ben Skeggs 2022-06-01 152 /* save the maximum numer of gpcs */
3ffa6f329b6100 Ben Skeggs 2022-06-01 @153 max_tpc_gpc = num_tpc_gpc[gpc] > max_tpc_gpc ? num_tpc_gpc[gpc] : max_tpc_gpc;
3ffa6f329b6100 Ben Skeggs 2022-06-01 154
3ffa6f329b6100 Ben Skeggs 2022-06-01 155 /*
3ffa6f329b6100 Ben Skeggs 2022-06-01 156 * Calculate ratio between TPC count and post-FS and post-SCG
3ffa6f329b6100 Ben Skeggs 2022-06-01 157 *
3ffa6f329b6100 Ben Skeggs 2022-06-01 158 * ratio represents relative throughput of the GPC
3ffa6f329b6100 Ben Skeggs 2022-06-01 159 */
3ffa6f329b6100 Ben Skeggs 2022-06-01 160 scg_gpc_pix_perf = scale_factor * num_tpc_gpc[gpc] / gr->tpc_nr[gpc];
3ffa6f329b6100 Ben Skeggs 2022-06-01 161 if (min_scg_gpc_pix_perf > scg_gpc_pix_perf)
3ffa6f329b6100 Ben Skeggs 2022-06-01 162 min_scg_gpc_pix_perf = scg_gpc_pix_perf;
3ffa6f329b6100 Ben Skeggs 2022-06-01 163
3ffa6f329b6100 Ben Skeggs 2022-06-01 164 /* Calculate # of surviving PES */
3ffa6f329b6100 Ben Skeggs 2022-06-01 165 for (pes = 0; pes < gr->ppc_nr[gpc]; pes++) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 166 /* Count the number of TPC on the set */
3ffa6f329b6100 Ben Skeggs 2022-06-01 167 num_tpc_mask = gr->ppc_tpc_mask[gpc][pes] & gpc_tpc_mask[gpc];
3ffa6f329b6100 Ben Skeggs 2022-06-01 168
3ffa6f329b6100 Ben Skeggs 2022-06-01 169 if ((gpc == disable_gpc) && (num_tpc_mask & BIT(disable_tpc))) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 170 if (WARN_ON(tpc_removed_pes))
3ffa6f329b6100 Ben Skeggs 2022-06-01 171 goto done;
3ffa6f329b6100 Ben Skeggs 2022-06-01 172
3ffa6f329b6100 Ben Skeggs 2022-06-01 173 num_tpc_mask &= ~BIT(disable_tpc);
3ffa6f329b6100 Ben Skeggs 2022-06-01 174 tpc_removed_pes = true;
3ffa6f329b6100 Ben Skeggs 2022-06-01 175 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 176
3ffa6f329b6100 Ben Skeggs 2022-06-01 177 if (hweight32(num_tpc_mask))
3ffa6f329b6100 Ben Skeggs 2022-06-01 178 scg_num_pes++;
3ffa6f329b6100 Ben Skeggs 2022-06-01 179 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 180 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 181
3ffa6f329b6100 Ben Skeggs 2022-06-01 182 if (WARN_ON(!tpc_removed_gpc || !tpc_removed_pes))
3ffa6f329b6100 Ben Skeggs 2022-06-01 183 goto done;
3ffa6f329b6100 Ben Skeggs 2022-06-01 184
3ffa6f329b6100 Ben Skeggs 2022-06-01 185 if (max_tpc_gpc == 0) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 186 *perf = 0;
3ffa6f329b6100 Ben Skeggs 2022-06-01 187 goto done_ok;
3ffa6f329b6100 Ben Skeggs 2022-06-01 188 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 189
3ffa6f329b6100 Ben Skeggs 2022-06-01 190 /* Now calculate perf */
3ffa6f329b6100 Ben Skeggs 2022-06-01 191 scg_world_perf = (scale_factor * scg_num_pes) / gr->ppc_total;
3ffa6f329b6100 Ben Skeggs 2022-06-01 192 deviation = 0;
3ffa6f329b6100 Ben Skeggs 2022-06-01 193 average_tpcs = scale_factor * average_tpcs / gr->gpc_nr;
3ffa6f329b6100 Ben Skeggs 2022-06-01 194 for (gpc = 0; gpc < gr->gpc_nr; gpc++) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 195 diff = average_tpcs - scale_factor * num_tpc_gpc[gpc];
3ffa6f329b6100 Ben Skeggs 2022-06-01 196 if (diff < 0)
3ffa6f329b6100 Ben Skeggs 2022-06-01 197 diff = -diff;
3ffa6f329b6100 Ben Skeggs 2022-06-01 198
3ffa6f329b6100 Ben Skeggs 2022-06-01 199 deviation += diff;
3ffa6f329b6100 Ben Skeggs 2022-06-01 200 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 201
3ffa6f329b6100 Ben Skeggs 2022-06-01 202 deviation /= gr->gpc_nr;
3ffa6f329b6100 Ben Skeggs 2022-06-01 203
3ffa6f329b6100 Ben Skeggs 2022-06-01 204 norm_tpc_deviation = deviation / max_tpc_gpc;
3ffa6f329b6100 Ben Skeggs 2022-06-01 205
3ffa6f329b6100 Ben Skeggs 2022-06-01 206 tpc_balance = scale_factor - norm_tpc_deviation;
3ffa6f329b6100 Ben Skeggs 2022-06-01 207
3ffa6f329b6100 Ben Skeggs 2022-06-01 208 if ((tpc_balance > scale_factor) ||
3ffa6f329b6100 Ben Skeggs 2022-06-01 209 (scg_world_perf > scale_factor) ||
3ffa6f329b6100 Ben Skeggs 2022-06-01 210 (min_scg_gpc_pix_perf > scale_factor) ||
3ffa6f329b6100 Ben Skeggs 2022-06-01 211 (norm_tpc_deviation > scale_factor)) {
3ffa6f329b6100 Ben Skeggs 2022-06-01 212 WARN_ON(1);
3ffa6f329b6100 Ben Skeggs 2022-06-01 213 goto done;
3ffa6f329b6100 Ben Skeggs 2022-06-01 214 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 215
3ffa6f329b6100 Ben Skeggs 2022-06-01 216 *perf = (pix_scale * min_scg_gpc_pix_perf) +
3ffa6f329b6100 Ben Skeggs 2022-06-01 217 (world_scale * scg_world_perf) +
3ffa6f329b6100 Ben Skeggs 2022-06-01 218 (tpc_scale * tpc_balance);
3ffa6f329b6100 Ben Skeggs 2022-06-01 219 done_ok:
3ffa6f329b6100 Ben Skeggs 2022-06-01 220 ret = 0;
3ffa6f329b6100 Ben Skeggs 2022-06-01 221 done:
3ffa6f329b6100 Ben Skeggs 2022-06-01 222 kfree(num_tpc_gpc);
3ffa6f329b6100 Ben Skeggs 2022-06-01 223 return ret;
3ffa6f329b6100 Ben Skeggs 2022-06-01 224 }
3ffa6f329b6100 Ben Skeggs 2022-06-01 225

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