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Message-ID: <39b5b07e-f1a5-4f90-bb3b-3742bb86f73f@huawei.com>
Date: Fri, 9 May 2025 14:44:40 +0800
From: Qinxin Xia <xiaqinxin@...wei.com>
To: Barry Song <21cnbao@...il.com>, Marek Szyprowski
<m.szyprowski@...sung.com>, Robin Murphy <robin.murphy@....com>
CC: <yangyicong@...wei.com>, <hch@....de>, <iommu@...ts.linux.dev>,
<jonathan.cameron@...wei.com>, <prime.zeng@...wei.com>,
<fanghao11@...wei.com>, <linux-kernel@...r.kernel.org>, <linuxarm@...wei.com>
Subject: Re: [PATCH v3 2/4] dma-mapping: benchmark: modify the framework to
adapt to more map modes
On 2025/5/9 11:41:31, Barry Song <21cnbao@...il.com> wrote:
> On Fri, May 9, 2025 at 2:02 PM Qinxin Xia <xiaqinxin@...wei.com> wrote:
>> In some service scenarios, the performance of dma_map_sg needs to be
>> tested to support different map modes for benchmarks. This patch adjusts
>> the DMA map benchmark framework to make the DMA map benchmark framework
>> more flexible and adaptable to other mapping modes in the future.
>> By abstracting the framework into four interfaces:prepare, unprepare,
>> do_map, and do_unmap.The new map schema can be introduced more easily
>> without major modifications to the existing code structure.
>>
>> Signed-off-by: Qinxin Xia <xiaqinxin@...wei.com>
> - stable@...r.kernel.org
> + Marek
> + Robin,
>
> Once the minor issues below are addressed, feel free to add:
>
> Reviewed-by: Barry Song <baohua@...nel.org>
OK
>> ---
>> include/linux/map_benchmark.h | 8 ++-
>> kernel/dma/map_benchmark.c | 122 +++++++++++++++++++++++++++-------
>> 2 files changed, 106 insertions(+), 24 deletions(-)
>>
>> diff --git a/include/linux/map_benchmark.h b/include/linux/map_benchmark.h
>> index 2ac2fe52f248..5294dfd1870f 100644
>> --- a/include/linux/map_benchmark.h
>> +++ b/include/linux/map_benchmark.h
>> @@ -15,6 +15,11 @@
>> #define DMA_MAP_TO_DEVICE 1
>> #define DMA_MAP_FROM_DEVICE 2
>>
>> +enum {
>> + DMA_MAP_SINGLE_MODE,
>> + DMA_MAP_MODE_MAX
>> +};
> Using a more specific namespace—such as DMA_MAP_BENCH_SINGLE_MODE
> and DMA_MAP_BENCH_MODE_MAX—would help avoid potential naming
> conflicts.
>
>> +
>> struct map_benchmark {
>> __u64 avg_map_100ns; /* average map latency in 100ns */
>> __u64 map_stddev; /* standard deviation of map latency */
>> @@ -27,6 +32,7 @@ struct map_benchmark {
>> __u32 dma_dir; /* DMA data direction */
>> __u32 dma_trans_ns; /* time for DMA transmission in ns */
>> __u32 granule; /* how many PAGE_SIZE will do map/unmap once a time */
>> - __u8 expansion[76]; /* For future use */
>> + __u8 map_mode; /* the mode of dma map */
>> + __u8 expansion[75]; /* For future use */
>> };
>> #endif /* _KERNEL_DMA_BENCHMARK_H */
>> diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
>> index cc19a3efea89..47a06b891db8 100644
>> --- a/kernel/dma/map_benchmark.c
>> +++ b/kernel/dma/map_benchmark.c
>> @@ -5,6 +5,7 @@
>>
>> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> +#include <linux/cleanup.h>
>> #include <linux/debugfs.h>
>> #include <linux/delay.h>
>> #include <linux/device.h>
>> @@ -31,17 +32,99 @@ struct map_benchmark_data {
>> atomic64_t loops;
>> };
>>
>> +struct map_benchmark_ops {
>> + void *(*prepare)(struct map_benchmark_data *map);
>> + void (*unprepare)(void *mparam);
>> + int (*do_map)(void *mparam);
>> + void (*do_unmap)(void *mparam);
>> +};
>> +
>> +struct dma_single_map_param {
>> + struct device *dev;
>> + dma_addr_t addr;
>> + void *xbuf;
>> + u32 npages;
>> + u32 dma_dir;
>> +};
>> +
>> +static void *dma_single_map_benchmark_prepare(struct map_benchmark_data *map)
>> +{
>> + struct dma_single_map_param *params __free(kfree) = kzalloc(sizeof(*params),
>> + GFP_KERNEL);
>> + if (!params)
>> + return NULL;
>> +
>> + params->npages = map->bparam.granule;
>> + params->dma_dir = map->bparam.dma_dir;
>> + params->dev = map->dev;
>> + params->xbuf = alloc_pages_exact(params->npages * PAGE_SIZE, GFP_KERNEL);
>> + if (!params->xbuf)
>> + return NULL;
>> +
>> + /*
>> + * 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.
>> + */
>> + if (params->dma_dir != DMA_FROM_DEVICE)
>> + memset(params->xbuf, 0x66, params->npages * PAGE_SIZE);
>> +
>> + return_ptr(params);
>> +}
>> +
>> +static void dma_single_map_benchmark_unprepare(void *mparam)
>> +{
>> + struct dma_single_map_param *params = mparam;
>> +
>> + free_pages_exact(params->xbuf, params->npages * PAGE_SIZE);
>> + kfree(params);
>> +}
>> +
>> +static int dma_single_map_benchmark_do_map(void *mparam)
>> +{
>> + struct dma_single_map_param *params = mparam;
>> + int ret = 0;
>> +
>> + params->addr = dma_map_single(params->dev, params->xbuf,
>> + params->npages * PAGE_SIZE, params->dma_dir);
>> + if (unlikely(dma_mapping_error(params->dev, params->addr))) {
>> + pr_err("dma_map_single failed on %s\n", dev_name(params->dev));
>> + ret = -ENOMEM;
>> + }
>> +
>> + return ret;
>> +}
>> +
>> +static void dma_single_map_benchmark_do_unmap(void *mparam)
>> +{
>> + struct dma_single_map_param *params = mparam;
>> +
>> + dma_unmap_single(params->dev, params->addr,
>> + params->npages * PAGE_SIZE, params->dma_dir);
>> +}
>> +
>> +static struct map_benchmark_ops dma_single_map_benchmark_ops = {
>> + .prepare = dma_single_map_benchmark_prepare,
>> + .unprepare = dma_single_map_benchmark_unprepare,
>> + .do_map = dma_single_map_benchmark_do_map,
>> + .do_unmap = dma_single_map_benchmark_do_unmap,
>> +};
>> +
>> +static struct map_benchmark_ops *dma_map_benchmark_ops[DMA_MAP_MODE_MAX] = {
>> + [DMA_MAP_SINGLE_MODE] = &dma_single_map_benchmark_ops,
>> +};
>> +
>> static int map_benchmark_thread(void *data)
>> {
>> - void *buf;
>> - dma_addr_t dma_addr;
>> struct map_benchmark_data *map = data;
>> - int npages = map->bparam.granule;
>> - u64 size = npages * PAGE_SIZE;
>> + __u8 map_mode = map->bparam.map_mode;
>> int ret = 0;
>>
>> - buf = alloc_pages_exact(size, GFP_KERNEL);
>> - if (!buf)
>> + struct map_benchmark_ops *mb_ops = dma_map_benchmark_ops[map_mode];
>> + void *mparam = mb_ops->prepare(map);
>> +
>> + if (!mparam)
>> return -ENOMEM;
>>
>> while (!kthread_should_stop()) {
>> @@ -49,23 +132,10 @@ static int map_benchmark_thread(void *data)
>> ktime_t map_stime, map_etime, unmap_stime, unmap_etime;
>> ktime_t map_delta, unmap_delta;
>>
>> - /*
>> - * 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.
>> - */
>> - if (map->dir != DMA_FROM_DEVICE)
>> - memset(buf, 0x66, size);
>> -
>> map_stime = ktime_get();
>> - dma_addr = dma_map_single(map->dev, buf, size, map->dir);
>> - if (unlikely(dma_mapping_error(map->dev, dma_addr))) {
>> - pr_err("dma_map_single failed on %s\n",
>> - dev_name(map->dev));
>> - ret = -ENOMEM;
>> + ret = mb_ops->do_map(mparam);
>> + if (ret)
>> goto out;
>> - }
>> map_etime = ktime_get();
>> map_delta = ktime_sub(map_etime, map_stime);
>>
>> @@ -73,7 +143,8 @@ static int map_benchmark_thread(void *data)
>> ndelay(map->bparam.dma_trans_ns);
>>
>> unmap_stime = ktime_get();
>> - dma_unmap_single(map->dev, dma_addr, size, map->dir);
>> + mb_ops->do_unmap(mparam);
>> +
>> unmap_etime = ktime_get();
>> unmap_delta = ktime_sub(unmap_etime, unmap_stime);
>>
>> @@ -108,7 +179,7 @@ static int map_benchmark_thread(void *data)
>> }
>>
>> out:
>> - free_pages_exact(buf, size);
>> + mb_ops->unprepare(mparam);
>> return ret;
>> }
>>
>> @@ -209,6 +280,11 @@ static long map_benchmark_ioctl(struct file *file, unsigned int cmd,
>>
>> switch (cmd) {
>> case DMA_MAP_BENCHMARK:
>> + if (map->bparam.map_mode >= DMA_MAP_MODE_MAX) {
>> + pr_err("invalid map mode\n");
>> + return -EINVAL;
>> + }
>> +
>> if (map->bparam.threads == 0 ||
>> map->bparam.threads > DMA_MAP_MAX_THREADS) {
>> pr_err("invalid thread number\n");
>> --
>> 2.33.0
>>
> Thanks
> Barry
Thanks
Qinxin
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