* [PATCH v2 1/2] dma-mapping: add benchmark support for streaming DMA APIs
2020-11-01 10:15 [PATCH v2 0/2] dma-mapping: provide a benchmark for streaming DMA mapping Barry Song
@ 2020-11-01 10:15 ` Barry Song
2020-11-01 18:57 ` kernel test robot
2020-11-01 19:22 ` kernel test robot
2020-11-01 10:15 ` [PATCH v2 2/2] selftests/dma: add test application for DMA_MAP_BENCHMARK Barry Song
1 sibling, 2 replies; 5+ messages in thread
From: Barry Song @ 2020-11-01 10:15 UTC (permalink / raw)
To: iommu, hch, robin.murphy, m.szyprowski
Cc: linux-kselftest, Shuah Khan, linuxarm, xuwei5, Will Deacon
Nowadays, there are increasing requirements to benchmark the performance
of dma_map and dma_unmap particually while the device is attached to an
IOMMU.
This patch enables the support. Users can run specified number of threads
to do dma_map_page and dma_unmap_page on a specific NUMA node with the
specified duration. Then dma_map_benchmark will calculate the average
latency for map and unmap.
A difficulity for this benchmark is that dma_map/unmap APIs must run on
a particular device. Each device might have different backend of IOMMU or
non-IOMMU.
So we use the driver_override to bind dma_map_benchmark to a particual
device by:
For platform devices:
echo dma_map_benchmark > /sys/bus/platform/devices/xxx/driver_override
echo xxx > /sys/bus/platform/drivers/xxx/unbind
echo xxx > /sys/bus/platform/drivers/dma_map_benchmark/bind
For PCI devices:
echo dma_map_benchmark > /sys/bus/pci/devices/0000:00:01.0/driver_override
echo 0000:00:01.0 > /sys/bus/pci/drivers/xxx/unbind
echo 0000:00:01.0 > /sys/bus/pci/drivers/dma_map_benchmark/bind
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
---
-v2:
* add PCI support; v1 supported platform devices only
* replace ssleep by msleep_interruptible() to permit users to exit
benchmark before it is completed
* many changes according to Robin's suggestions, thanks! Robin
- add standard deviation output to reflect the worst case
- check users' parameters strictly like the number of threads
- make cache dirty before dma_map
- fix unpaired dma_map_page and dma_unmap_single;
- remove redundant "long long" before ktime_to_ns();
- use devm_add_action();
- wakeup all threads together after they are ready
kernel/dma/Kconfig | 8 +
kernel/dma/Makefile | 1 +
kernel/dma/map_benchmark.c | 295 +++++++++++++++++++++++++++++++++++++
3 files changed, 304 insertions(+)
create mode 100644 kernel/dma/map_benchmark.c
diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig
index c99de4a21458..949c53da5991 100644
--- a/kernel/dma/Kconfig
+++ b/kernel/dma/Kconfig
@@ -225,3 +225,11 @@ config DMA_API_DEBUG_SG
is technically out-of-spec.
If unsure, say N.
+
+config DMA_MAP_BENCHMARK
+ bool "Enable benchmarking of streaming DMA mapping"
+ help
+ Provides /sys/kernel/debug/dma_map_benchmark that helps with testing
+ performance of dma_(un)map_page.
+
+ See tools/testing/selftests/dma/dma_map_benchmark.c
diff --git a/kernel/dma/Makefile b/kernel/dma/Makefile
index dc755ab68aab..7aa6b26b1348 100644
--- a/kernel/dma/Makefile
+++ b/kernel/dma/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_DMA_API_DEBUG) += debug.o
obj-$(CONFIG_SWIOTLB) += swiotlb.o
obj-$(CONFIG_DMA_COHERENT_POOL) += pool.o
obj-$(CONFIG_DMA_REMAP) += remap.o
+obj-$(CONFIG_DMA_MAP_BENCHMARK) += map_benchmark.o
diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
new file mode 100644
index 000000000000..ac397758087b
--- /dev/null
+++ b/kernel/dma/map_benchmark.c
@@ -0,0 +1,295 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Hisilicon Limited.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/dma-mapping.h>
+#include <linux/kernel.h>
+#include <linux/kthread.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/timekeeping.h>
+
+#define DMA_MAP_BENCHMARK _IOWR('d', 1, struct map_benchmark)
+#define DMA_MAP_MAX_THREADS 1024
+#define DMA_MAP_MAX_SECONDS 300
+
+struct map_benchmark {
+ __u64 avg_map_100ns; /* average map latency in 100ns */
+ __u64 map_stddev; /* standard deviation of map latency */
+ __u64 avg_unmap_100ns; /* as above */
+ __u64 unmap_stddev;
+ __u32 threads; /* how many threads will do map/unmap in parallel */
+ __u32 seconds; /* how long the test will last */
+ int node; /* which numa node this benchmark will run on */
+ __u64 expansion[10]; /* For future use */
+};
+
+struct map_benchmark_data {
+ struct map_benchmark bparam;
+ struct device *dev;
+ struct dentry *debugfs;
+ atomic64_t sum_map_100ns;
+ atomic64_t sum_unmap_100ns;
+ atomic64_t sum_square_map;
+ atomic64_t sum_square_unmap;
+ atomic64_t loops;
+};
+
+static int map_benchmark_thread(void *data)
+{
+ void *buf;
+ dma_addr_t dma_addr;
+ struct map_benchmark_data *map = data;
+ int ret = 0;
+
+ buf = (void *)__get_free_page(GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ while (!kthread_should_stop()) {
+ __u64 map_100ns, unmap_100ns, map_square, unmap_square;
+ ktime_t map_stime, map_etime, unmap_stime, unmap_etime;
+
+ /*
+ * for a non-coherent device, if we don't stain them in the cache,
+ * this will give an underestimate of the real-world overhead of
+ * BIDIRECTIONAL or TO_DEVICE mappings
+ * 66 means evertything goes well! 66 is lucky.
+ */
+ memset(buf, 0x66, PAGE_SIZE);
+
+ map_stime = ktime_get();
+ dma_addr = dma_map_single(map->dev, buf, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ if (unlikely(dma_mapping_error(map->dev, dma_addr))) {
+ pr_err("dma_map_single failed on %s\n", dev_name(map->dev));
+ ret = -ENOMEM;
+ goto out;
+ }
+ map_etime = ktime_get();
+
+ unmap_stime = ktime_get();
+ dma_unmap_single(map->dev, dma_addr, PAGE_SIZE, DMA_BIDIRECTIONAL);
+ unmap_etime = ktime_get();
+
+ /* calculate sum and sum of squares */
+ map_100ns = ktime_to_ns(ktime_sub(map_etime, map_stime)) / 100;
+ unmap_100ns = ktime_to_ns(ktime_sub(unmap_etime, unmap_stime)) / 100;
+ map_square = map_100ns * map_100ns;
+ unmap_square = unmap_100ns * unmap_100ns;
+
+ atomic64_add(map_100ns, &map->sum_map_100ns);
+ atomic64_add(unmap_100ns, &map->sum_unmap_100ns);
+ atomic64_add(map_square, &map->sum_square_map);
+ atomic64_add(unmap_square, &map->sum_square_unmap);
+ atomic64_inc(&map->loops);
+ }
+
+out:
+ free_page((unsigned long)buf);
+ return ret;
+}
+
+static int do_map_benchmark(struct map_benchmark_data *map)
+{
+ struct task_struct **tsk;
+ int threads = map->bparam.threads;
+ int node = map->bparam.node;
+ const cpumask_t *cpu_mask = cpumask_of_node(node);
+ __u64 loops;
+ int ret = 0;
+ int i;
+
+ tsk = kmalloc_array(threads, sizeof(tsk), GFP_KERNEL);
+ if (!tsk)
+ return -ENOMEM;
+
+ get_device(map->dev);
+
+ for (i = 0; i < threads; i++) {
+ tsk[i] = kthread_create_on_node(map_benchmark_thread, map,
+ map->bparam.node, "dma-map-benchmark/%d", i);
+ if (IS_ERR(tsk[i])) {
+ pr_err("create dma_map thread failed\n");
+ ret = PTR_ERR(tsk[i]);
+ goto out;
+ }
+
+ if (node != NUMA_NO_NODE && node_online(node))
+ kthread_bind_mask(tsk[i], cpu_mask);
+ }
+
+ /* clear the old value in the previous benchmark */
+ atomic64_set(&map->sum_map_100ns, 0);
+ atomic64_set(&map->sum_unmap_100ns, 0);
+ atomic64_set(&map->sum_square_map, 0);
+ atomic64_set(&map->sum_square_unmap, 0);
+ atomic64_set(&map->loops, 0);
+
+ for (i = 0; i < threads; i++)
+ wake_up_process(tsk[i]);
+
+ msleep_interruptible(map->bparam.seconds * 1000);
+
+ /* wait for the completion of benchmark threads */
+ for (i = 0; i < threads; i++) {
+ ret = kthread_stop(tsk[i]);
+ if (ret)
+ goto out;
+ }
+
+ loops = atomic64_read(&map->loops);
+ if (likely(loops > 0)) {
+ __u64 map_variance, unmap_variance;
+
+ /* average latency */
+ map->bparam.avg_map_100ns = atomic64_read(&map->sum_map_100ns) / loops;
+ map->bparam.avg_unmap_100ns = atomic64_read(&map->sum_unmap_100ns) / loops;
+
+ /* standard deviation of latency */
+ map_variance = atomic64_read(&map->sum_square_map) / loops -
+ map->bparam.avg_map_100ns * map->bparam.avg_map_100ns;
+ unmap_variance = atomic64_read(&map->sum_square_unmap) / loops -
+ map->bparam.avg_unmap_100ns * map->bparam.avg_unmap_100ns;
+ map->bparam.map_stddev = int_sqrt64(map_variance);
+ map->bparam.unmap_stddev = int_sqrt64(unmap_variance);
+ }
+
+out:
+ put_device(map->dev);
+ kfree(tsk);
+ return ret;
+}
+
+static long map_benchmark_ioctl(struct file *filep, unsigned int cmd,
+ unsigned long arg)
+{
+ struct map_benchmark_data *map = filep->private_data;
+ int ret;
+
+ if (copy_from_user(&map->bparam, (void __user *)arg, sizeof(map->bparam)))
+ return -EFAULT;
+
+ switch (cmd) {
+ case DMA_MAP_BENCHMARK:
+ if (map->bparam.threads == 0 || map->bparam.threads > DMA_MAP_MAX_THREADS) {
+ pr_err("invalid thread number\n");
+ return -EINVAL;
+ }
+ if (map->bparam.seconds == 0 || map->bparam.seconds > DMA_MAP_MAX_SECONDS) {
+ pr_err("invalid duration seconds\n");
+ return -EINVAL;
+ }
+
+ ret = do_map_benchmark(map);
+ break;
+ default:
+ return -EINVAL;
+ }
+
+ if (copy_to_user((void __user *)arg, &map->bparam, sizeof(map->bparam)))
+ return -EFAULT;
+
+ return ret;
+}
+
+static const struct file_operations map_benchmark_fops = {
+ .open = simple_open,
+ .unlocked_ioctl = map_benchmark_ioctl,
+};
+
+static void map_benchmark_remove_debugfs(void *data)
+{
+ struct map_benchmark_data *map = (struct map_benchmark_data *)data;
+
+ debugfs_remove(map->debugfs);
+}
+
+static int __map_benchmark_probe(struct device *dev)
+{
+ struct dentry *entry;
+ struct map_benchmark_data *map;
+ int ret;
+
+ map = devm_kzalloc(dev, sizeof(*map), GFP_KERNEL);
+ if (!map)
+ return -ENOMEM;
+ map->dev = dev;
+
+ ret = devm_add_action(dev, map_benchmark_remove_debugfs, map);
+ if (ret) {
+ pr_err("Can't add debugfs remove action\n");
+ return ret;
+ }
+
+ /*
+ * we only permit a device bound with this driver, 2nd probe
+ * will fail
+ */
+ entry = debugfs_create_file("dma_map_benchmark", 0600, NULL, map,
+ &map_benchmark_fops);
+ if (IS_ERR(entry))
+ return PTR_ERR(entry);
+ map->debugfs = entry;
+
+ return 0;
+}
+
+static int map_benchmark_platform_probe(struct platform_device *pdev)
+{
+ return __map_benchmark_probe(&pdev->dev);
+}
+
+static struct platform_driver map_benchmark_platform_driver = {
+ .driver = {
+ .name = "dma_map_benchmark",
+ },
+ .probe = map_benchmark_platform_probe,
+};
+
+static int map_benchmark_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+ return __map_benchmark_probe(&pdev->dev);
+}
+
+static struct pci_driver map_benchmark_pci_driver = {
+ .name = "dma_map_benchmark",
+ .probe = map_benchmark_pci_probe,
+};
+
+static int __init map_benchmark_init(void)
+{
+ int ret;
+
+ ret = pci_register_driver(&map_benchmark_pci_driver);
+ if (ret)
+ return ret;
+
+ ret = platform_driver_register(&map_benchmark_platform_driver);
+ if (ret) {
+ pci_unregister_driver(&map_benchmark_pci_driver);
+ return ret;
+ }
+
+ return 0;
+}
+
+static void __exit map_benchmark_cleanup(void)
+{
+ platform_driver_unregister(&map_benchmark_platform_driver);
+ pci_unregister_driver(&map_benchmark_pci_driver);
+}
+
+module_init(map_benchmark_init);
+module_exit(map_benchmark_cleanup);
+
+MODULE_AUTHOR("Barry Song <song.bao.hua@hisilicon.com>");
+MODULE_DESCRIPTION("dma_map benchmark driver");
+MODULE_LICENSE("GPL");
--
2.25.1
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^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH v2 2/2] selftests/dma: add test application for DMA_MAP_BENCHMARK
2020-11-01 10:15 [PATCH v2 0/2] dma-mapping: provide a benchmark for streaming DMA mapping Barry Song
2020-11-01 10:15 ` [PATCH v2 1/2] dma-mapping: add benchmark support for streaming DMA APIs Barry Song
@ 2020-11-01 10:15 ` Barry Song
1 sibling, 0 replies; 5+ messages in thread
From: Barry Song @ 2020-11-01 10:15 UTC (permalink / raw)
To: iommu, hch, robin.murphy, m.szyprowski
Cc: linux-kselftest, Shuah Khan, linuxarm, xuwei5, Will Deacon
This patch provides the test application for DMA_MAP_BENCHMARK.
Before running the test application, we need to bind a device to dma_map_
benchmark driver. For example, unbind "xxx" from its original driver and
bind to dma_map_benchmark:
echo dma_map_benchmark > /sys/bus/platform/devices/xxx/driver_override
echo xxx > /sys/bus/platform/drivers/xxx/unbind
echo xxx > /sys/bus/platform/drivers/dma_map_benchmark/bind
Another example for PCI devices:
echo dma_map_benchmark > /sys/bus/pci/devices/0000:00:01.0/driver_override
echo 0000:00:01.0 > /sys/bus/pci/drivers/xxx/unbind
echo 0000:00:01.0 > /sys/bus/pci/drivers/dma_map_benchmark/bind
The below command will run 16 threads on numa node 0 for 10 seconds on
the device bound to dma_map_benchmark platform_driver or pci_driver:
./dma_map_benchmark -t 16 -s 10 -n 0
dma mapping benchmark: threads:16 seconds:10
average map latency(us):1.1 standard deviation:1.9
average unmap latency(us):0.5 standard deviation:0.8
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Will Deacon <will@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Signed-off-by: Barry Song <song.bao.hua@hisilicon.com>
---
-v2:
* check parameters like threads, seconds strictly
* print standard deviation for latencies
MAINTAINERS | 6 ++
tools/testing/selftests/dma/Makefile | 6 ++
tools/testing/selftests/dma/config | 1 +
.../testing/selftests/dma/dma_map_benchmark.c | 87 +++++++++++++++++++
4 files changed, 100 insertions(+)
create mode 100644 tools/testing/selftests/dma/Makefile
create mode 100644 tools/testing/selftests/dma/config
create mode 100644 tools/testing/selftests/dma/dma_map_benchmark.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 608fc8484c02..a1e38d5e14f6 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5247,6 +5247,12 @@ F: include/linux/dma-mapping.h
F: include/linux/dma-map-ops.h
F: kernel/dma/
+DMA MAPPING BENCHMARK
+M: Barry Song <song.bao.hua@hisilicon.com>
+L: iommu@lists.linux-foundation.org
+F: kernel/dma/map_benchmark.c
+F: tools/testing/selftests/dma/
+
DMA-BUF HEAPS FRAMEWORK
M: Sumit Semwal <sumit.semwal@linaro.org>
R: Benjamin Gaignard <benjamin.gaignard@linaro.org>
diff --git a/tools/testing/selftests/dma/Makefile b/tools/testing/selftests/dma/Makefile
new file mode 100644
index 000000000000..aa8e8b5b3864
--- /dev/null
+++ b/tools/testing/selftests/dma/Makefile
@@ -0,0 +1,6 @@
+# SPDX-License-Identifier: GPL-2.0
+CFLAGS += -I../../../../usr/include/
+
+TEST_GEN_PROGS := dma_map_benchmark
+
+include ../lib.mk
diff --git a/tools/testing/selftests/dma/config b/tools/testing/selftests/dma/config
new file mode 100644
index 000000000000..6102ee3c43cd
--- /dev/null
+++ b/tools/testing/selftests/dma/config
@@ -0,0 +1 @@
+CONFIG_DMA_MAP_BENCHMARK=y
diff --git a/tools/testing/selftests/dma/dma_map_benchmark.c b/tools/testing/selftests/dma/dma_map_benchmark.c
new file mode 100644
index 000000000000..4778df0c458f
--- /dev/null
+++ b/tools/testing/selftests/dma/dma_map_benchmark.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 Hisilicon Limited.
+ */
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <linux/types.h>
+
+#define DMA_MAP_BENCHMARK _IOWR('d', 1, struct map_benchmark)
+#define DMA_MAP_MAX_THREADS 1024
+#define DMA_MAP_MAX_SECONDS 300
+
+struct map_benchmark {
+ __u64 avg_map_100ns; /* average map latency in 100ns */
+ __u64 map_stddev; /* standard deviation of map latency */
+ __u64 avg_unmap_100ns; /* as above */
+ __u64 unmap_stddev;
+ __u32 threads; /* how many threads will do map/unmap in parallel */
+ __u32 seconds; /* how long the test will last */
+ int node; /* which numa node this benchmark will run on */
+ __u64 expansion[10]; /* For future use */
+};
+
+int main(int argc, char **argv)
+{
+ struct map_benchmark map;
+ int fd, opt;
+ /* default single thread, run 20 seconds on NUMA_NO_NODE */
+ int threads = 1, seconds = 20, node = -1;
+ int cmd = DMA_MAP_BENCHMARK;
+ char *p;
+
+ while ((opt = getopt(argc, argv, "t:s:n:")) != -1) {
+ switch (opt) {
+ case 't':
+ threads = atoi(optarg);
+ break;
+ case 's':
+ seconds = atoi(optarg);
+ break;
+ case 'n':
+ node = atoi(optarg);
+ break;
+ default:
+ return -1;
+ }
+ }
+
+ if (threads <= 0 || threads > DMA_MAP_MAX_THREADS) {
+ fprintf(stderr, "invalid number of threads, must be in 1-%d\n",
+ DMA_MAP_MAX_THREADS);
+ exit(1);
+ }
+
+ if (seconds <= 0 || seconds > DMA_MAP_MAX_SECONDS) {
+ fprintf(stderr, "invalid number of seconds, must be in 1-%d\n",
+ DMA_MAP_MAX_SECONDS);
+ exit(1);
+ }
+
+ fd = open("/sys/kernel/debug/dma_map_benchmark", O_RDWR);
+ if (fd == -1) {
+ perror("open");
+ exit(1);
+ }
+
+ map.seconds = seconds;
+ map.threads = threads;
+ map.node = node;
+ if (ioctl(fd, cmd, &map)) {
+ perror("ioctl");
+ exit(1);
+ }
+
+ printf("dma mapping benchmark: threads:%d seconds:%d\n", threads, seconds);
+ printf("average map latency(us):%.1f standard deviation:%.1f\n",
+ map.avg_map_100ns/10.0, map.map_stddev/10.0);
+ printf("average unmap latency(us):%.1f standard deviation:%.1f\n",
+ map.avg_unmap_100ns/10.0, map.unmap_stddev/10.0);
+
+ return 0;
+}
--
2.25.1
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^ permalink raw reply related [flat|nested] 5+ messages in thread