kernel/dma/map_benchmark.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2020 HiSilicon Limited.
   4  */
   5
   6 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/debugfs.h>
   9 #include <linux/delay.h>
  10 #include <linux/device.h>
  11 #include <linux/dma-mapping.h>
  12 #include <linux/kernel.h>
  13 #include <linux/kthread.h>
  14 #include <linux/map_benchmark.h>
  15 #include <linux/math64.h>
  16 #include <linux/module.h>
  17 #include <linux/pci.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/slab.h>
  20 #include <linux/timekeeping.h>
  21
  22 struct map_benchmark_data {
  23         struct map_benchmark bparam;
  24         struct device *dev;
  25         struct dentry  *debugfs;
  26         enum dma_data_direction dir;
  27         atomic64_t sum_map_100ns;
  28         atomic64_t sum_unmap_100ns;
  29         atomic64_t sum_sq_map;
  30         atomic64_t sum_sq_unmap;
  31         atomic64_t loops;
  32 };
  33
  34 static int map_benchmark_thread(void *data)
  35 {
  36         void *buf;
  37         dma_addr_t dma_addr;
  38         struct map_benchmark_data *map = data;
  39         int npages = map->bparam.granule;
  40         u64 size = npages * PAGE_SIZE;
  41         int ret = 0;
  42
  43         buf = alloc_pages_exact(size, GFP_KERNEL);
  44         if (!buf)
  45                 return -ENOMEM;
  46
  47         while (!kthread_should_stop())  {
  48                 u64 map_100ns, unmap_100ns, map_sq, unmap_sq;
  49                 ktime_t map_stime, map_etime, unmap_stime, unmap_etime;
  50                 ktime_t map_delta, unmap_delta;
  51
  52                 /*
  53                  * for a non-coherent device, if we don't stain them in the
  54                  * cache, this will give an underestimate of the real-world
  55                  * overhead of BIDIRECTIONAL or TO_DEVICE mappings;
  56                  * 66 means evertything goes well! 66 is lucky.
  57                  */
  58                 if (map->dir != DMA_FROM_DEVICE)
  59                         memset(buf, 0x66, size);
  60
  61                 map_stime = ktime_get();
  62                 dma_addr = dma_map_single(map->dev, buf, size, map->dir);
  63                 if (unlikely(dma_mapping_error(map->dev, dma_addr))) {
  64                         pr_err("dma_map_single failed on %s\n",
  65                                 dev_name(map->dev));
  66                         ret = -ENOMEM;
  67                         goto out;
  68                 }
  69                 map_etime = ktime_get();
  70                 map_delta = ktime_sub(map_etime, map_stime);
  71
  72                 /* Pretend DMA is transmitting */
  73                 ndelay(map->bparam.dma_trans_ns);
  74
  75                 unmap_stime = ktime_get();
  76                 dma_unmap_single(map->dev, dma_addr, size, map->dir);
  77                 unmap_etime = ktime_get();
  78                 unmap_delta = ktime_sub(unmap_etime, unmap_stime);
  79
  80                 /* calculate sum and sum of squares */
  81
  82                 map_100ns = div64_ul(map_delta,  100);
  83                 unmap_100ns = div64_ul(unmap_delta, 100);
  84                 map_sq = map_100ns * map_100ns;
  85                 unmap_sq = unmap_100ns * unmap_100ns;
  86
  87                 atomic64_add(map_100ns, &map->sum_map_100ns);
  88                 atomic64_add(unmap_100ns, &map->sum_unmap_100ns);
  89                 atomic64_add(map_sq, &map->sum_sq_map);
  90                 atomic64_add(unmap_sq, &map->sum_sq_unmap);
  91                 atomic64_inc(&map->loops);
  92
  93                 /*
  94                  * We may test for a long time so periodically check whether
  95                  * we need to schedule to avoid starving the others. Otherwise
  96                  * we may hangup the kernel in a non-preemptible kernel when
  97                  * the test kthreads number >= CPU number, the test kthreads
  98                  * will run endless on every CPU since the thread resposible
  99                  * for notifying the kthread stop (in do_map_benchmark())
 100                  * could not be scheduled.
 101                  *
 102                  * Note this may degrade the test concurrency since the test
 103                  * threads may need to share the CPU time with other load
 104                  * in the system. So it's recommended to run this benchmark
 105                  * on an idle system.
 106                  */
 107                 cond_resched();
 108         }
 109
 110 out:
 111         free_pages_exact(buf, size);
 112         return ret;
 113 }
 114
 115 static int do_map_benchmark(struct map_benchmark_data *map)
 116 {
 117         struct task_struct **tsk;
 118         int threads = map->bparam.threads;
 119         int node = map->bparam.node;
 120         u64 loops;
 121         int ret = 0;
 122         int i;
 123
 124         tsk = kmalloc_array(threads, sizeof(*tsk), GFP_KERNEL);
 125         if (!tsk)
 126                 return -ENOMEM;
 127
 128         get_device(map->dev);
 129
 130         for (i = 0; i < threads; i++) {
 131                 tsk[i] = kthread_create_on_node(map_benchmark_thread, map,
 132                                 map->bparam.node, "dma-map-benchmark/%d", i);
 133                 if (IS_ERR(tsk[i])) {
 134                         pr_err("create dma_map thread failed\n");
 135                         ret = PTR_ERR(tsk[i]);
 136                         while (--i >= 0)
 137                                 kthread_stop(tsk[i]);
 138                         goto out;
 139                 }
 140
 141                 if (node != NUMA_NO_NODE)
 142                         kthread_bind_mask(tsk[i], cpumask_of_node(node));
 143         }
 144
 145         /* clear the old value in the previous benchmark */
 146         atomic64_set(&map->sum_map_100ns, 0);
 147         atomic64_set(&map->sum_unmap_100ns, 0);
 148         atomic64_set(&map->sum_sq_map, 0);
 149         atomic64_set(&map->sum_sq_unmap, 0);
 150         atomic64_set(&map->loops, 0);
 151
 152         for (i = 0; i < threads; i++) {
 153                 get_task_struct(tsk[i]);
 154                 wake_up_process(tsk[i]);
 155         }
 156
 157         msleep_interruptible(map->bparam.seconds * 1000);
 158
 159         /* wait for the completion of all started benchmark threads */
 160         for (i = 0; i < threads; i++) {
 161                 int kthread_ret = kthread_stop_put(tsk[i]);
 162
 163                 if (kthread_ret)
 164                         ret = kthread_ret;
 165         }
 166
 167         if (ret)
 168                 goto out;
 169
 170         loops = atomic64_read(&map->loops);
 171         if (likely(loops > 0)) {
 172                 u64 map_variance, unmap_variance;
 173                 u64 sum_map = atomic64_read(&map->sum_map_100ns);
 174                 u64 sum_unmap = atomic64_read(&map->sum_unmap_100ns);
 175                 u64 sum_sq_map = atomic64_read(&map->sum_sq_map);
 176                 u64 sum_sq_unmap = atomic64_read(&map->sum_sq_unmap);
 177
 178                 /* average latency */
 179                 map->bparam.avg_map_100ns = div64_u64(sum_map, loops);
 180                 map->bparam.avg_unmap_100ns = div64_u64(sum_unmap, loops);
 181
 182                 /* standard deviation of latency */
 183                 map_variance = div64_u64(sum_sq_map, loops) -
 184                                 map->bparam.avg_map_100ns *
 185                                 map->bparam.avg_map_100ns;
 186                 unmap_variance = div64_u64(sum_sq_unmap, loops) -
 187                                 map->bparam.avg_unmap_100ns *
 188                                 map->bparam.avg_unmap_100ns;
 189                 map->bparam.map_stddev = int_sqrt64(map_variance);
 190                 map->bparam.unmap_stddev = int_sqrt64(unmap_variance);
 191         }
 192
 193 out:
 194         put_device(map->dev);
 195         kfree(tsk);
 196         return ret;
 197 }
 198
 199 static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
 200                 unsigned long arg)
 201 {
 202         struct map_benchmark_data *map = file->private_data;
 203         void __user *argp = (void __user *)arg;
 204         u64 old_dma_mask;
 205         int ret;
 206
 207         if (copy_from_user(&map->bparam, argp, sizeof(map->bparam)))
 208                 return -EFAULT;
 209
 210         switch (cmd) {
 211         case DMA_MAP_BENCHMARK:
 212                 if (map->bparam.threads == 0 ||
 213                     map->bparam.threads > DMA_MAP_MAX_THREADS) {
 214                         pr_err("invalid thread number\n");
 215                         return -EINVAL;
 216                 }
 217
 218                 if (map->bparam.seconds == 0 ||
 219                     map->bparam.seconds > DMA_MAP_MAX_SECONDS) {
 220                         pr_err("invalid duration seconds\n");
 221                         return -EINVAL;
 222                 }
 223
 224                 if (map->bparam.dma_trans_ns > DMA_MAP_MAX_TRANS_DELAY) {
 225                         pr_err("invalid transmission delay\n");
 226                         return -EINVAL;
 227                 }
 228
 229                 if (map->bparam.node != NUMA_NO_NODE &&
 230                     (map->bparam.node < 0 || map->bparam.node >= MAX_NUMNODES ||
 231                      !node_possible(map->bparam.node))) {
 232                         pr_err("invalid numa node\n");
 233                         return -EINVAL;
 234                 }
 235
 236                 if (map->bparam.granule < 1 || map->bparam.granule > 1024) {
 237                         pr_err("invalid granule size\n");
 238                         return -EINVAL;
 239                 }
 240
 241                 switch (map->bparam.dma_dir) {
 242                 case DMA_MAP_BIDIRECTIONAL:
 243                         map->dir = DMA_BIDIRECTIONAL;
 244                         break;
 245                 case DMA_MAP_FROM_DEVICE:
 246                         map->dir = DMA_FROM_DEVICE;
 247                         break;
 248                 case DMA_MAP_TO_DEVICE:
 249                         map->dir = DMA_TO_DEVICE;
 250                         break;
 251                 default:
 252                         pr_err("invalid DMA direction\n");
 253                         return -EINVAL;
 254                 }
 255
 256                 old_dma_mask = dma_get_mask(map->dev);
 257
 258                 ret = dma_set_mask(map->dev,
 259                                    DMA_BIT_MASK(map->bparam.dma_bits));
 260                 if (ret) {
 261                         pr_err("failed to set dma_mask on device %s\n",
 262                                 dev_name(map->dev));
 263                         return -EINVAL;
 264                 }
 265
 266                 ret = do_map_benchmark(map);
 267
 268                 /*
 269                  * restore the original dma_mask as many devices' dma_mask are
 270                  * set by architectures, acpi, busses. When we bind them back
 271                  * to their original drivers, those drivers shouldn't see
 272                  * dma_mask changed by benchmark
 273                  */
 274                 dma_set_mask(map->dev, old_dma_mask);
 275
 276                 if (ret)
 277                         return ret;
 278                 break;
 279         default:
 280                 return -EINVAL;
 281         }
 282
 283         if (copy_to_user(argp, &map->bparam, sizeof(map->bparam)))
 284                 return -EFAULT;
 285
 286         return ret;
 287 }
 288
 289 static const struct file_operations map_benchmark_fops = {
 290         .open                   = simple_open,
 291         .unlocked_ioctl         = map_benchmark_ioctl,
 292 };
 293
 294 static void map_benchmark_remove_debugfs(void *data)
 295 {
 296         struct map_benchmark_data *map = (struct map_benchmark_data *)data;
 297
 298         debugfs_remove(map->debugfs);
 299 }
 300
 301 static int __map_benchmark_probe(struct device *dev)
 302 {
 303         struct dentry *entry;
 304         struct map_benchmark_data *map;
 305         int ret;
 306
 307         map = devm_kzalloc(dev, sizeof(*map), GFP_KERNEL);
 308         if (!map)
 309                 return -ENOMEM;
 310         map->dev = dev;
 311
 312         ret = devm_add_action(dev, map_benchmark_remove_debugfs, map);
 313         if (ret) {
 314                 pr_err("Can't add debugfs remove action\n");
 315                 return ret;
 316         }
 317
 318         /*
 319          * we only permit a device bound with this driver, 2nd probe
 320          * will fail
 321          */
 322         entry = debugfs_create_file("dma_map_benchmark", 0600, NULL, map,
 323                         &map_benchmark_fops);
 324         if (IS_ERR(entry))
 325                 return PTR_ERR(entry);
 326         map->debugfs = entry;
 327
 328         return 0;
 329 }
 330
 331 static int map_benchmark_platform_probe(struct platform_device *pdev)
 332 {
 333         return __map_benchmark_probe(&pdev->dev);
 334 }
 335
 336 static struct platform_driver map_benchmark_platform_driver = {
 337         .driver         = {
 338                 .name   = "dma_map_benchmark",
 339         },
 340         .probe = map_benchmark_platform_probe,
 341 };
 342
 343 static int
 344 map_benchmark_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 345 {
 346         return __map_benchmark_probe(&pdev->dev);
 347 }
 348
 349 static struct pci_driver map_benchmark_pci_driver = {
 350         .name   = "dma_map_benchmark",
 351         .probe  = map_benchmark_pci_probe,
 352 };
 353
 354 static int __init map_benchmark_init(void)
 355 {
 356         int ret;
 357
 358         ret = pci_register_driver(&map_benchmark_pci_driver);
 359         if (ret)
 360                 return ret;
 361
 362         ret = platform_driver_register(&map_benchmark_platform_driver);
 363         if (ret) {
 364                 pci_unregister_driver(&map_benchmark_pci_driver);
 365                 return ret;
 366         }
 367
 368         return 0;
 369 }
 370
 371 static void __exit map_benchmark_cleanup(void)
 372 {
 373         platform_driver_unregister(&map_benchmark_platform_driver);
 374         pci_unregister_driver(&map_benchmark_pci_driver);
 375 }
 376
 377 module_init(map_benchmark_init);
 378 module_exit(map_benchmark_cleanup);
 379
 380 MODULE_AUTHOR("Barry Song <song.bao.hua@hisilicon.com>");
 381 MODULE_DESCRIPTION("dma_map benchmark driver");