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/math64.h>
  15 #include <linux/module.h>
  16 #include <linux/pci.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19 #include <linux/timekeeping.h>
  20
  21 #define DMA_MAP_BENCHMARK       _IOWR('d', 1, struct map_benchmark)
  22 #define DMA_MAP_MAX_THREADS     1024
  23 #define DMA_MAP_MAX_SECONDS     300
  24
  25 #define DMA_MAP_BIDIRECTIONAL   0
  26 #define DMA_MAP_TO_DEVICE       1
  27 #define DMA_MAP_FROM_DEVICE     2
  28
  29 struct map_benchmark {
  30         __u64 avg_map_100ns; /* average map latency in 100ns */
  31         __u64 map_stddev; /* standard deviation of map latency */
  32         __u64 avg_unmap_100ns; /* as above */
  33         __u64 unmap_stddev;
  34         __u32 threads; /* how many threads will do map/unmap in parallel */
  35         __u32 seconds; /* how long the test will last */
  36         __s32 node; /* which numa node this benchmark will run on */
  37         __u32 dma_bits; /* DMA addressing capability */
  38         __u32 dma_dir; /* DMA data direction */
  39         __u64 expansion[10];    /* For future use */
  40 };
  41
  42 struct map_benchmark_data {
  43         struct map_benchmark bparam;
  44         struct device *dev;
  45         struct dentry  *debugfs;
  46         enum dma_data_direction dir;
  47         atomic64_t sum_map_100ns;
  48         atomic64_t sum_unmap_100ns;
  49         atomic64_t sum_sq_map;
  50         atomic64_t sum_sq_unmap;
  51         atomic64_t loops;
  52 };
  53
  54 static int map_benchmark_thread(void *data)
  55 {
  56         void *buf;
  57         dma_addr_t dma_addr;
  58         struct map_benchmark_data *map = data;
  59         int ret = 0;
  60
  61         buf = (void *)__get_free_page(GFP_KERNEL);
  62         if (!buf)
  63                 return -ENOMEM;
  64
  65         while (!kthread_should_stop())  {
  66                 u64 map_100ns, unmap_100ns, map_sq, unmap_sq;
  67                 ktime_t map_stime, map_etime, unmap_stime, unmap_etime;
  68                 ktime_t map_delta, unmap_delta;
  69
  70                 /*
  71                  * for a non-coherent device, if we don't stain them in the
  72                  * cache, this will give an underestimate of the real-world
  73                  * overhead of BIDIRECTIONAL or TO_DEVICE mappings;
  74                  * 66 means evertything goes well! 66 is lucky.
  75                  */
  76                 if (map->dir != DMA_FROM_DEVICE)
  77                         memset(buf, 0x66, PAGE_SIZE);
  78
  79                 map_stime = ktime_get();
  80                 dma_addr = dma_map_single(map->dev, buf, PAGE_SIZE, map->dir);
  81                 if (unlikely(dma_mapping_error(map->dev, dma_addr))) {
  82                         pr_err("dma_map_single failed on %s\n",
  83                                 dev_name(map->dev));
  84                         ret = -ENOMEM;
  85                         goto out;
  86                 }
  87                 map_etime = ktime_get();
  88                 map_delta = ktime_sub(map_etime, map_stime);
  89
  90                 unmap_stime = ktime_get();
  91                 dma_unmap_single(map->dev, dma_addr, PAGE_SIZE, map->dir);
  92                 unmap_etime = ktime_get();
  93                 unmap_delta = ktime_sub(unmap_etime, unmap_stime);
  94
  95                 /* calculate sum and sum of squares */
  96
  97                 map_100ns = div64_ul(map_delta,  100);
  98                 unmap_100ns = div64_ul(unmap_delta, 100);
  99                 map_sq = map_100ns * map_100ns;
 100                 unmap_sq = unmap_100ns * unmap_100ns;
 101
 102                 atomic64_add(map_100ns, &map->sum_map_100ns);
 103                 atomic64_add(unmap_100ns, &map->sum_unmap_100ns);
 104                 atomic64_add(map_sq, &map->sum_sq_map);
 105                 atomic64_add(unmap_sq, &map->sum_sq_unmap);
 106                 atomic64_inc(&map->loops);
 107         }
 108
 109 out:
 110         free_page((unsigned long)buf);
 111         return ret;
 112 }
 113
 114 static int do_map_benchmark(struct map_benchmark_data *map)
 115 {
 116         struct task_struct **tsk;
 117         int threads = map->bparam.threads;
 118         int node = map->bparam.node;
 119         const cpumask_t *cpu_mask = cpumask_of_node(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                         goto out;
 137                 }
 138
 139                 if (node != NUMA_NO_NODE)
 140                         kthread_bind_mask(tsk[i], cpu_mask);
 141         }
 142
 143         /* clear the old value in the previous benchmark */
 144         atomic64_set(&map->sum_map_100ns, 0);
 145         atomic64_set(&map->sum_unmap_100ns, 0);
 146         atomic64_set(&map->sum_sq_map, 0);
 147         atomic64_set(&map->sum_sq_unmap, 0);
 148         atomic64_set(&map->loops, 0);
 149
 150         for (i = 0; i < threads; i++)
 151                 wake_up_process(tsk[i]);
 152
 153         msleep_interruptible(map->bparam.seconds * 1000);
 154
 155         /* wait for the completion of benchmark threads */
 156         for (i = 0; i < threads; i++) {
 157                 ret = kthread_stop(tsk[i]);
 158                 if (ret)
 159                         goto out;
 160         }
 161
 162         loops = atomic64_read(&map->loops);
 163         if (likely(loops > 0)) {
 164                 u64 map_variance, unmap_variance;
 165                 u64 sum_map = atomic64_read(&map->sum_map_100ns);
 166                 u64 sum_unmap = atomic64_read(&map->sum_unmap_100ns);
 167                 u64 sum_sq_map = atomic64_read(&map->sum_sq_map);
 168                 u64 sum_sq_unmap = atomic64_read(&map->sum_sq_unmap);
 169
 170                 /* average latency */
 171                 map->bparam.avg_map_100ns = div64_u64(sum_map, loops);
 172                 map->bparam.avg_unmap_100ns = div64_u64(sum_unmap, loops);
 173
 174                 /* standard deviation of latency */
 175                 map_variance = div64_u64(sum_sq_map, loops) -
 176                                 map->bparam.avg_map_100ns *
 177                                 map->bparam.avg_map_100ns;
 178                 unmap_variance = div64_u64(sum_sq_unmap, loops) -
 179                                 map->bparam.avg_unmap_100ns *
 180                                 map->bparam.avg_unmap_100ns;
 181                 map->bparam.map_stddev = int_sqrt64(map_variance);
 182                 map->bparam.unmap_stddev = int_sqrt64(unmap_variance);
 183         }
 184
 185 out:
 186         put_device(map->dev);
 187         kfree(tsk);
 188         return ret;
 189 }
 190
 191 static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
 192                 unsigned long arg)
 193 {
 194         struct map_benchmark_data *map = file->private_data;
 195         void __user *argp = (void __user *)arg;
 196         u64 old_dma_mask;
 197
 198         int ret;
 199
 200         if (copy_from_user(&map->bparam, argp, sizeof(map->bparam)))
 201                 return -EFAULT;
 202
 203         switch (cmd) {
 204         case DMA_MAP_BENCHMARK:
 205                 if (map->bparam.threads == 0 ||
 206                     map->bparam.threads > DMA_MAP_MAX_THREADS) {
 207                         pr_err("invalid thread number\n");
 208                         return -EINVAL;
 209                 }
 210
 211                 if (map->bparam.seconds == 0 ||
 212                     map->bparam.seconds > DMA_MAP_MAX_SECONDS) {
 213                         pr_err("invalid duration seconds\n");
 214                         return -EINVAL;
 215                 }
 216
 217                 if (map->bparam.node != NUMA_NO_NODE &&
 218                     !node_possible(map->bparam.node)) {
 219                         pr_err("invalid numa node\n");
 220                         return -EINVAL;
 221                 }
 222
 223                 switch (map->bparam.dma_dir) {
 224                 case DMA_MAP_BIDIRECTIONAL:
 225                         map->dir = DMA_BIDIRECTIONAL;
 226                         break;
 227                 case DMA_MAP_FROM_DEVICE:
 228                         map->dir = DMA_FROM_DEVICE;
 229                         break;
 230                 case DMA_MAP_TO_DEVICE:
 231                         map->dir = DMA_TO_DEVICE;
 232                         break;
 233                 default:
 234                         pr_err("invalid DMA direction\n");
 235                         return -EINVAL;
 236                 }
 237
 238                 old_dma_mask = dma_get_mask(map->dev);
 239
 240                 ret = dma_set_mask(map->dev,
 241                                    DMA_BIT_MASK(map->bparam.dma_bits));
 242                 if (ret) {
 243                         pr_err("failed to set dma_mask on device %s\n",
 244                                 dev_name(map->dev));
 245                         return -EINVAL;
 246                 }
 247
 248                 ret = do_map_benchmark(map);
 249
 250                 /*
 251                  * restore the original dma_mask as many devices' dma_mask are
 252                  * set by architectures, acpi, busses. When we bind them back
 253                  * to their original drivers, those drivers shouldn't see
 254                  * dma_mask changed by benchmark
 255                  */
 256                 dma_set_mask(map->dev, old_dma_mask);
 257                 break;
 258         default:
 259                 return -EINVAL;
 260         }
 261
 262         if (copy_to_user(argp, &map->bparam, sizeof(map->bparam)))
 263                 return -EFAULT;
 264
 265         return ret;
 266 }
 267
 268 static const struct file_operations map_benchmark_fops = {
 269         .open                   = simple_open,
 270         .unlocked_ioctl         = map_benchmark_ioctl,
 271 };
 272
 273 static void map_benchmark_remove_debugfs(void *data)
 274 {
 275         struct map_benchmark_data *map = (struct map_benchmark_data *)data;
 276
 277         debugfs_remove(map->debugfs);
 278 }
 279
 280 static int __map_benchmark_probe(struct device *dev)
 281 {
 282         struct dentry *entry;
 283         struct map_benchmark_data *map;
 284         int ret;
 285
 286         map = devm_kzalloc(dev, sizeof(*map), GFP_KERNEL);
 287         if (!map)
 288                 return -ENOMEM;
 289         map->dev = dev;
 290
 291         ret = devm_add_action(dev, map_benchmark_remove_debugfs, map);
 292         if (ret) {
 293                 pr_err("Can't add debugfs remove action\n");
 294                 return ret;
 295         }
 296
 297         /*
 298          * we only permit a device bound with this driver, 2nd probe
 299          * will fail
 300          */
 301         entry = debugfs_create_file("dma_map_benchmark", 0600, NULL, map,
 302                         &map_benchmark_fops);
 303         if (IS_ERR(entry))
 304                 return PTR_ERR(entry);
 305         map->debugfs = entry;
 306
 307         return 0;
 308 }
 309
 310 static int map_benchmark_platform_probe(struct platform_device *pdev)
 311 {
 312         return __map_benchmark_probe(&pdev->dev);
 313 }
 314
 315 static struct platform_driver map_benchmark_platform_driver = {
 316         .driver         = {
 317                 .name   = "dma_map_benchmark",
 318         },
 319         .probe = map_benchmark_platform_probe,
 320 };
 321
 322 static int
 323 map_benchmark_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 324 {
 325         return __map_benchmark_probe(&pdev->dev);
 326 }
 327
 328 static struct pci_driver map_benchmark_pci_driver = {
 329         .name   = "dma_map_benchmark",
 330         .probe  = map_benchmark_pci_probe,
 331 };
 332
 333 static int __init map_benchmark_init(void)
 334 {
 335         int ret;
 336
 337         ret = pci_register_driver(&map_benchmark_pci_driver);
 338         if (ret)
 339                 return ret;
 340
 341         ret = platform_driver_register(&map_benchmark_platform_driver);
 342         if (ret) {
 343                 pci_unregister_driver(&map_benchmark_pci_driver);
 344                 return ret;
 345         }
 346
 347         return 0;
 348 }
 349
 350 static void __exit map_benchmark_cleanup(void)
 351 {
 352         platform_driver_unregister(&map_benchmark_platform_driver);
 353         pci_unregister_driver(&map_benchmark_pci_driver);
 354 }
 355
 356 module_init(map_benchmark_init);
 357 module_exit(map_benchmark_cleanup);
 358
 359 MODULE_AUTHOR("Barry Song <song.bao.hua@hisilicon.com>");
 360 MODULE_DESCRIPTION("dma_map benchmark driver");
 361 MODULE_LICENSE("GPL");