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Message-ID: <ab20d545-7dc8-4dd0-bd05-256089034ec3@huawei.com>
Date: Tue, 8 Apr 2025 17:42:38 +0800
From: Qinxin Xia <xiaqinxin@...wei.com>
To: Barry Song <21cnbao@...il.com>
CC: <chenxiang66@...ilicon.com>, <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>
Subject: Re: [PATCH 1/3] dma mapping benchmark: modify the framework to adapt
to more map modes
在 2025/4/7 13:28, Barry Song 写道:
> On Wed, Feb 12, 2025 at 3:27 PM Qinxin Xia <xiaqinxin@...wei.com> wrote:
>> In this patch map_benchmark abstract in four interface: prepare, unprepare,
>> do_map, do_unmap. When there's a new mode to add, need four steps:
>> 1) Add the mode in map_benchmark.h
>>
>> 2) Defines the mode param, like struct dma_xxx_map_param, and this object
>> will be return in prepare and as input parameter in other ops;
>>
>> 3) Defines the ops functions:prepare, unprepare, do_map, do_unmap.
>>
>> 4) Add the new mode in dma_map_benchmark_ops.
>>
>> Signed-off-by: Qinxin Xia <xiaqinxin@...wei.com>
>> ---
>> include/linux/map_benchmark.h | 6 ++
>> kernel/dma/map_benchmark.c | 122 +++++++++++++++++++++++++++-------
>> 2 files changed, 105 insertions(+), 23 deletions(-)
>>
>> diff --git a/include/linux/map_benchmark.h b/include/linux/map_benchmark.h
>> index 62674c83bde4..054db02a03a7 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
>> +};
>> +
>> struct map_benchmark {
>> __u64 avg_map_100ns; /* average map latency in 100ns */
>> __u64 map_stddev; /* standard deviation of map latency */
>> @@ -27,5 +32,6 @@ 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 map_mode; /* the mode of dma map */
> We previously added some padding to ensure the uABI remained consistent.
> I just noticed that Tiantao’s commit (8ddde07a3d285a0f3cec, "dma-mapping:
> benchmark: extract a common header file for map_benchmark definition")
> accidentally removed that padding, which has completely broken the ABIs.
>
> Could you send a patch to fix this regression, and CC it to
> stable@...r.kernel.org before adding the new field which should
> use the expansion[] instead.
OK, I will send a patch to fix this regression in next version.
>
>> };
>> #endif /* _KERNEL_DMA_BENCHMARK_H */
>> diff --git a/kernel/dma/map_benchmark.c b/kernel/dma/map_benchmark.c
>> index cc19a3efea89..d8ec0ce058d8 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 +32,98 @@ struct map_benchmark_data {
>> atomic64_t loops;
>> };
>>
>> +struct map_benchmark_ops {
>> + void *(*prepare)(struct map_benchmark_data *map);
>> + void (*unprepare)(void *arg);
>> + int (*do_map)(void *arg);
>> + int (*do_unmap)(void *arg);
>> +};
>> +
>> +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 *mparam __free(kfree) = kzalloc(sizeof(*mparam),
>> + GFP_KERNEL);
>> + if (!mparam)
>> + return NULL;
>> +
>> + mparam->npages = map->bparam.granule;
>> + mparam->dma_dir = map->bparam.dma_dir;
>> + mparam->dev = map->dev;
>> + mparam->xbuf = alloc_pages_exact(mparam->npages * PAGE_SIZE, GFP_KERNEL);
>> + if (!mparam->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 (mparam->dma_dir != DMA_FROM_DEVICE)
>> + memset(mparam->xbuf, 0x66, mparam->npages * PAGE_SIZE);
>> +
>> + return_ptr(mparam);
>> +}
>> +
>> +static void dma_single_map_benchmark_unprepare(void *arg)
>> +{
>> + struct dma_single_map_param *mparam = arg;
>> +
>> + free_pages_exact(mparam->xbuf, mparam->npages * PAGE_SIZE);
>> + kfree(mparam);
>> +}
>> +
>> +static int dma_single_map_benchmark_do_map(void *arg)
>> +{
>> + struct dma_single_map_param *mparam = arg;
>> +
>> + mparam->addr = dma_map_single(mparam->dev, mparam->xbuf,
>> + mparam->npages * PAGE_SIZE, mparam->dma_dir);
>> + if (unlikely(dma_mapping_error(mparam->dev, mparam->addr))) {
>> + pr_err("dma_map_single failed on %s\n", dev_name(mparam->dev));
>> + return -ENOMEM;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int dma_single_map_benchmark_do_unmap(void *arg)
>> +{
>> + struct dma_single_map_param *mparam = arg;
>> +
>> + dma_unmap_single(mparam->dev, mparam->addr,
>> + mparam->npages * PAGE_SIZE, mparam->dma_dir);
>> + return 0;
>> +}
>> +
>> +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)
>> + void *arg = dma_map_benchmark_ops[map_mode]->prepare(map);
>> +
>> + if (!arg)
>> return -ENOMEM;
>>
>> while (!kthread_should_stop()) {
>> @@ -49,23 +131,10 @@ 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 = dma_map_benchmark_ops[map_mode]->do_map(arg);
>> + if (ret)
>> goto out;
>> - }
>> map_etime = ktime_get();
>> map_delta = ktime_sub(map_etime, map_stime);
>>
>> @@ -73,7 +142,9 @@ 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);
>> + ret = dma_map_benchmark_ops[map_mode]->do_unmap(arg);
>> + if (ret)
>> + goto out;
>> 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);
>> + dma_map_benchmark_ops[map_mode]->unprepare(arg);
>> 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
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