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synced 2024-09-04 01:49:36 +00:00
![Barry Song](/assets/img/avatar_default.png)
In a real dma mapping user case, after dma_map is done, data will be transmit. Thus, in multi-threaded user scenario, IOMMU contention should not be that severe. For example, if users enable multiple threads to send network packets through 1G/10G/100Gbps NIC, usually the steps will be: map -> transmission -> unmap. Transmission delay reduces the contention of IOMMU. Here a delay is added to simulate the transmission between map and unmap so that the tested result could be more accurate for TX and simple RX. A typical TX transmission for NIC would be like: map -> TX -> unmap since the socket buffers come from OS. Simple RX model eg. disk driver, is also map -> RX -> unmap, but real RX model in a NIC could be more complicated considering packets can come spontaneously and many drivers are using pre-mapped buffers pool. This is in the TBD list. Signed-off-by: Barry Song <song.bao.hua@hisilicon.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
375 lines
9.3 KiB
C
375 lines
9.3 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Copyright (C) 2020 Hisilicon Limited.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/debugfs.h>
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#include <linux/delay.h>
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#include <linux/device.h>
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#include <linux/dma-mapping.h>
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#include <linux/kernel.h>
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#include <linux/kthread.h>
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#include <linux/math64.h>
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#include <linux/module.h>
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#include <linux/pci.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/timekeeping.h>
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#define DMA_MAP_BENCHMARK _IOWR('d', 1, struct map_benchmark)
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#define DMA_MAP_MAX_THREADS 1024
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#define DMA_MAP_MAX_SECONDS 300
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#define DMA_MAP_MAX_TRANS_DELAY (10 * NSEC_PER_MSEC)
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#define DMA_MAP_BIDIRECTIONAL 0
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#define DMA_MAP_TO_DEVICE 1
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#define DMA_MAP_FROM_DEVICE 2
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struct map_benchmark {
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__u64 avg_map_100ns; /* average map latency in 100ns */
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__u64 map_stddev; /* standard deviation of map latency */
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__u64 avg_unmap_100ns; /* as above */
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__u64 unmap_stddev;
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__u32 threads; /* how many threads will do map/unmap in parallel */
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__u32 seconds; /* how long the test will last */
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__s32 node; /* which numa node this benchmark will run on */
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__u32 dma_bits; /* DMA addressing capability */
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__u32 dma_dir; /* DMA data direction */
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__u32 dma_trans_ns; /* time for DMA transmission in ns */
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__u8 expansion[80]; /* For future use */
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};
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struct map_benchmark_data {
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struct map_benchmark bparam;
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struct device *dev;
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struct dentry *debugfs;
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enum dma_data_direction dir;
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atomic64_t sum_map_100ns;
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atomic64_t sum_unmap_100ns;
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atomic64_t sum_sq_map;
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atomic64_t sum_sq_unmap;
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atomic64_t loops;
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};
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static int map_benchmark_thread(void *data)
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{
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void *buf;
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dma_addr_t dma_addr;
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struct map_benchmark_data *map = data;
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int ret = 0;
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buf = (void *)__get_free_page(GFP_KERNEL);
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if (!buf)
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return -ENOMEM;
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while (!kthread_should_stop()) {
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u64 map_100ns, unmap_100ns, map_sq, unmap_sq;
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ktime_t map_stime, map_etime, unmap_stime, unmap_etime;
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ktime_t map_delta, unmap_delta;
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/*
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* for a non-coherent device, if we don't stain them in the
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* cache, this will give an underestimate of the real-world
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* overhead of BIDIRECTIONAL or TO_DEVICE mappings;
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* 66 means evertything goes well! 66 is lucky.
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*/
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if (map->dir != DMA_FROM_DEVICE)
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memset(buf, 0x66, PAGE_SIZE);
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map_stime = ktime_get();
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dma_addr = dma_map_single(map->dev, buf, PAGE_SIZE, map->dir);
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if (unlikely(dma_mapping_error(map->dev, dma_addr))) {
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pr_err("dma_map_single failed on %s\n",
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dev_name(map->dev));
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ret = -ENOMEM;
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goto out;
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}
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map_etime = ktime_get();
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map_delta = ktime_sub(map_etime, map_stime);
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/* Pretend DMA is transmitting */
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ndelay(map->bparam.dma_trans_ns);
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unmap_stime = ktime_get();
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dma_unmap_single(map->dev, dma_addr, PAGE_SIZE, map->dir);
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unmap_etime = ktime_get();
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unmap_delta = ktime_sub(unmap_etime, unmap_stime);
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/* calculate sum and sum of squares */
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map_100ns = div64_ul(map_delta, 100);
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unmap_100ns = div64_ul(unmap_delta, 100);
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map_sq = map_100ns * map_100ns;
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unmap_sq = unmap_100ns * unmap_100ns;
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atomic64_add(map_100ns, &map->sum_map_100ns);
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atomic64_add(unmap_100ns, &map->sum_unmap_100ns);
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atomic64_add(map_sq, &map->sum_sq_map);
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atomic64_add(unmap_sq, &map->sum_sq_unmap);
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atomic64_inc(&map->loops);
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}
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out:
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free_page((unsigned long)buf);
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return ret;
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}
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static int do_map_benchmark(struct map_benchmark_data *map)
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{
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struct task_struct **tsk;
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int threads = map->bparam.threads;
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int node = map->bparam.node;
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const cpumask_t *cpu_mask = cpumask_of_node(node);
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u64 loops;
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int ret = 0;
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int i;
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tsk = kmalloc_array(threads, sizeof(*tsk), GFP_KERNEL);
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if (!tsk)
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return -ENOMEM;
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get_device(map->dev);
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for (i = 0; i < threads; i++) {
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tsk[i] = kthread_create_on_node(map_benchmark_thread, map,
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map->bparam.node, "dma-map-benchmark/%d", i);
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if (IS_ERR(tsk[i])) {
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pr_err("create dma_map thread failed\n");
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ret = PTR_ERR(tsk[i]);
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goto out;
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}
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if (node != NUMA_NO_NODE)
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kthread_bind_mask(tsk[i], cpu_mask);
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}
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/* clear the old value in the previous benchmark */
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atomic64_set(&map->sum_map_100ns, 0);
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atomic64_set(&map->sum_unmap_100ns, 0);
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atomic64_set(&map->sum_sq_map, 0);
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atomic64_set(&map->sum_sq_unmap, 0);
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atomic64_set(&map->loops, 0);
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for (i = 0; i < threads; i++) {
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get_task_struct(tsk[i]);
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wake_up_process(tsk[i]);
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}
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msleep_interruptible(map->bparam.seconds * 1000);
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/* wait for the completion of benchmark threads */
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for (i = 0; i < threads; i++) {
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ret = kthread_stop(tsk[i]);
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if (ret)
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goto out;
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}
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loops = atomic64_read(&map->loops);
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if (likely(loops > 0)) {
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u64 map_variance, unmap_variance;
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u64 sum_map = atomic64_read(&map->sum_map_100ns);
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u64 sum_unmap = atomic64_read(&map->sum_unmap_100ns);
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u64 sum_sq_map = atomic64_read(&map->sum_sq_map);
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u64 sum_sq_unmap = atomic64_read(&map->sum_sq_unmap);
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/* average latency */
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map->bparam.avg_map_100ns = div64_u64(sum_map, loops);
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map->bparam.avg_unmap_100ns = div64_u64(sum_unmap, loops);
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/* standard deviation of latency */
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map_variance = div64_u64(sum_sq_map, loops) -
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map->bparam.avg_map_100ns *
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map->bparam.avg_map_100ns;
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unmap_variance = div64_u64(sum_sq_unmap, loops) -
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map->bparam.avg_unmap_100ns *
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map->bparam.avg_unmap_100ns;
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map->bparam.map_stddev = int_sqrt64(map_variance);
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map->bparam.unmap_stddev = int_sqrt64(unmap_variance);
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}
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out:
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for (i = 0; i < threads; i++)
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put_task_struct(tsk[i]);
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put_device(map->dev);
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kfree(tsk);
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return ret;
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}
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static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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struct map_benchmark_data *map = file->private_data;
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void __user *argp = (void __user *)arg;
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u64 old_dma_mask;
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int ret;
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if (copy_from_user(&map->bparam, argp, sizeof(map->bparam)))
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return -EFAULT;
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switch (cmd) {
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case DMA_MAP_BENCHMARK:
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if (map->bparam.threads == 0 ||
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map->bparam.threads > DMA_MAP_MAX_THREADS) {
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pr_err("invalid thread number\n");
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return -EINVAL;
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}
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if (map->bparam.seconds == 0 ||
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map->bparam.seconds > DMA_MAP_MAX_SECONDS) {
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pr_err("invalid duration seconds\n");
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return -EINVAL;
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}
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if (map->bparam.dma_trans_ns > DMA_MAP_MAX_TRANS_DELAY) {
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pr_err("invalid transmission delay\n");
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return -EINVAL;
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}
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if (map->bparam.node != NUMA_NO_NODE &&
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!node_possible(map->bparam.node)) {
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pr_err("invalid numa node\n");
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return -EINVAL;
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}
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switch (map->bparam.dma_dir) {
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case DMA_MAP_BIDIRECTIONAL:
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map->dir = DMA_BIDIRECTIONAL;
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break;
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case DMA_MAP_FROM_DEVICE:
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map->dir = DMA_FROM_DEVICE;
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break;
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case DMA_MAP_TO_DEVICE:
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map->dir = DMA_TO_DEVICE;
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break;
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default:
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pr_err("invalid DMA direction\n");
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return -EINVAL;
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}
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old_dma_mask = dma_get_mask(map->dev);
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ret = dma_set_mask(map->dev,
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DMA_BIT_MASK(map->bparam.dma_bits));
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if (ret) {
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pr_err("failed to set dma_mask on device %s\n",
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dev_name(map->dev));
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return -EINVAL;
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}
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ret = do_map_benchmark(map);
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/*
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* restore the original dma_mask as many devices' dma_mask are
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* set by architectures, acpi, busses. When we bind them back
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* to their original drivers, those drivers shouldn't see
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* dma_mask changed by benchmark
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*/
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dma_set_mask(map->dev, old_dma_mask);
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break;
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default:
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return -EINVAL;
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}
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if (copy_to_user(argp, &map->bparam, sizeof(map->bparam)))
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return -EFAULT;
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return ret;
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}
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static const struct file_operations map_benchmark_fops = {
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.open = simple_open,
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.unlocked_ioctl = map_benchmark_ioctl,
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};
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static void map_benchmark_remove_debugfs(void *data)
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{
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struct map_benchmark_data *map = (struct map_benchmark_data *)data;
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debugfs_remove(map->debugfs);
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}
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static int __map_benchmark_probe(struct device *dev)
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{
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struct dentry *entry;
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struct map_benchmark_data *map;
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int ret;
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map = devm_kzalloc(dev, sizeof(*map), GFP_KERNEL);
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if (!map)
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return -ENOMEM;
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map->dev = dev;
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ret = devm_add_action(dev, map_benchmark_remove_debugfs, map);
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if (ret) {
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pr_err("Can't add debugfs remove action\n");
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return ret;
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}
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/*
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* we only permit a device bound with this driver, 2nd probe
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* will fail
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*/
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entry = debugfs_create_file("dma_map_benchmark", 0600, NULL, map,
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&map_benchmark_fops);
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if (IS_ERR(entry))
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return PTR_ERR(entry);
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map->debugfs = entry;
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return 0;
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}
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static int map_benchmark_platform_probe(struct platform_device *pdev)
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{
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return __map_benchmark_probe(&pdev->dev);
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}
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static struct platform_driver map_benchmark_platform_driver = {
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.driver = {
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.name = "dma_map_benchmark",
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},
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.probe = map_benchmark_platform_probe,
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};
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static int
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map_benchmark_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
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{
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return __map_benchmark_probe(&pdev->dev);
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}
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static struct pci_driver map_benchmark_pci_driver = {
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.name = "dma_map_benchmark",
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.probe = map_benchmark_pci_probe,
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};
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static int __init map_benchmark_init(void)
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{
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int ret;
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ret = pci_register_driver(&map_benchmark_pci_driver);
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if (ret)
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return ret;
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ret = platform_driver_register(&map_benchmark_platform_driver);
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if (ret) {
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pci_unregister_driver(&map_benchmark_pci_driver);
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return ret;
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}
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return 0;
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}
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static void __exit map_benchmark_cleanup(void)
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{
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platform_driver_unregister(&map_benchmark_platform_driver);
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pci_unregister_driver(&map_benchmark_pci_driver);
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}
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module_init(map_benchmark_init);
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module_exit(map_benchmark_cleanup);
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MODULE_AUTHOR("Barry Song <song.bao.hua@hisilicon.com>");
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MODULE_DESCRIPTION("dma_map benchmark driver");
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MODULE_LICENSE("GPL");
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