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
22struct 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
34static 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(i: map_100ns, v: &map->sum_map_100ns);
88 atomic64_add(i: unmap_100ns, v: &map->sum_unmap_100ns);
89 atomic64_add(i: map_sq, v: &map->sum_sq_map);
90 atomic64_add(i: unmap_sq, v: &map->sum_sq_unmap);
91 atomic64_inc(v: &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
110out:
111 free_pages_exact(virt: buf, size);
112 return ret;
113}
114
115static 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(dev: map->dev);
129
130 for (i = 0; i < threads; i++) {
131 tsk[i] = kthread_create_on_node(threadfn: map_benchmark_thread, data: map,
132 node: map->bparam.node, namefmt: "dma-map-benchmark/%d", i);
133 if (IS_ERR(ptr: tsk[i])) {
134 pr_err("create dma_map thread failed\n");
135 ret = PTR_ERR(ptr: tsk[i]);
136 while (--i >= 0)
137 kthread_stop(k: tsk[i]);
138 goto out;
139 }
140
141 if (node != NUMA_NO_NODE)
142 kthread_bind_mask(k: tsk[i], mask: cpumask_of_node(node));
143 }
144
145 /* clear the old value in the previous benchmark */
146 atomic64_set(v: &map->sum_map_100ns, i: 0);
147 atomic64_set(v: &map->sum_unmap_100ns, i: 0);
148 atomic64_set(v: &map->sum_sq_map, i: 0);
149 atomic64_set(v: &map->sum_sq_unmap, i: 0);
150 atomic64_set(v: &map->loops, i: 0);
151
152 for (i = 0; i < threads; i++) {
153 get_task_struct(t: tsk[i]);
154 wake_up_process(tsk: tsk[i]);
155 }
156
157 msleep_interruptible(msecs: 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(k: tsk[i]);
162
163 if (kthread_ret)
164 ret = kthread_ret;
165 }
166
167 if (ret)
168 goto out;
169
170 loops = atomic64_read(v: &map->loops);
171 if (likely(loops > 0)) {
172 u64 map_variance, unmap_variance;
173 u64 sum_map = atomic64_read(v: &map->sum_map_100ns);
174 u64 sum_unmap = atomic64_read(v: &map->sum_unmap_100ns);
175 u64 sum_sq_map = atomic64_read(v: &map->sum_sq_map);
176 u64 sum_sq_unmap = atomic64_read(v: &map->sum_sq_unmap);
177
178 /* average latency */
179 map->bparam.avg_map_100ns = div64_u64(dividend: sum_map, divisor: loops);
180 map->bparam.avg_unmap_100ns = div64_u64(dividend: sum_unmap, divisor: loops);
181
182 /* standard deviation of latency */
183 map_variance = div64_u64(dividend: sum_sq_map, divisor: loops) -
184 map->bparam.avg_map_100ns *
185 map->bparam.avg_map_100ns;
186 unmap_variance = div64_u64(dividend: sum_sq_unmap, divisor: loops) -
187 map->bparam.avg_unmap_100ns *
188 map->bparam.avg_unmap_100ns;
189 map->bparam.map_stddev = int_sqrt64(x: map_variance);
190 map->bparam.unmap_stddev = int_sqrt64(x: unmap_variance);
191 }
192
193out:
194 put_device(dev: map->dev);
195 kfree(objp: tsk);
196 return ret;
197}
198
199static 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(to: &map->bparam, from: argp, n: 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(dev: map->dev);
257
258 ret = dma_set_mask(dev: 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(dev: map->dev, mask: old_dma_mask);
275
276 if (ret)
277 return ret;
278 break;
279 default:
280 return -EINVAL;
281 }
282
283 if (copy_to_user(to: argp, from: &map->bparam, n: sizeof(map->bparam)))
284 return -EFAULT;
285
286 return ret;
287}
288
289static const struct file_operations map_benchmark_fops = {
290 .open = simple_open,
291 .unlocked_ioctl = map_benchmark_ioctl,
292};
293
294static void map_benchmark_remove_debugfs(void *data)
295{
296 struct map_benchmark_data *map = (struct map_benchmark_data *)data;
297
298 debugfs_remove(dentry: map->debugfs);
299}
300
301static 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, size: 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(ptr: entry))
325 return PTR_ERR(ptr: entry);
326 map->debugfs = entry;
327
328 return 0;
329}
330
331static int map_benchmark_platform_probe(struct platform_device *pdev)
332{
333 return __map_benchmark_probe(dev: &pdev->dev);
334}
335
336static struct platform_driver map_benchmark_platform_driver = {
337 .driver = {
338 .name = "dma_map_benchmark",
339 },
340 .probe = map_benchmark_platform_probe,
341};
342
343static int
344map_benchmark_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
345{
346 return __map_benchmark_probe(dev: &pdev->dev);
347}
348
349static struct pci_driver map_benchmark_pci_driver = {
350 .name = "dma_map_benchmark",
351 .probe = map_benchmark_pci_probe,
352};
353
354static 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(dev: &map_benchmark_pci_driver);
365 return ret;
366 }
367
368 return 0;
369}
370
371static void __exit map_benchmark_cleanup(void)
372{
373 platform_driver_unregister(&map_benchmark_platform_driver);
374 pci_unregister_driver(dev: &map_benchmark_pci_driver);
375}
376
377module_init(map_benchmark_init);
378module_exit(map_benchmark_cleanup);
379
380MODULE_AUTHOR("Barry Song <song.bao.hua@hisilicon.com>");
381MODULE_DESCRIPTION("dma_map benchmark driver");
382

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source code of linux/kernel/dma/map_benchmark.c