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 --- -v3: * fix build issues reported by 0day kernel test robot -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()

kernel/dma/Kconfig | 8 + kernel/dma/Makefile | 1 + kernel/dma/map_benchmark.c | 296 +++++++++++++++++++++++++++++++++++++ 3 files changed, 305 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..dc4e5ff48a2d --- /dev/null +++ b/kernel/dma/map_benchmark.c @@ -0,0 +1,296 @@ +// 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/math64.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 = div64_ul(ktime_to_ns(ktime_sub(map_etime, map_stime)), 100); + unmap_100ns = div64_ul(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 = div64_u64(atomic64_read(&map->sum_map_100ns), loops); + map->bparam.avg_unmap_100ns = div64_u64(atomic64_read(&map->sum_unmap_100ns), loops); + + /* standard deviation of latency */ + map_variance = div64_u64(atomic64_read(&map->sum_square_map), loops) - + map->bparam.avg_map_100ns * map->bparam.avg_map_100ns; + unmap_variance = div64_u64(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");

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 --- 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; +}