Re: [PATCH v4 21/23] mm/gup_benchmark: support pin_user_pages() and related calls

[Ira Weiny <ira.weiny@intel.com>]

On Tue, Nov 12, 2019 at 08:27:08PM -0800, John Hubbard wrote:
> Up until now, gup_benchmark supported testing of the
> following kernel functions:
> 
> * get_user_pages(): via the '-U' command line option
> * get_user_pages_longterm(): via the '-L' command line option
> * get_user_pages_fast(): as the default (no options required)
> 
> Add test coverage for the new corresponding pin_*() functions:
> 
> * pin_user_pages(): via the '-c' command line option
> * pin_longterm_pages(): via the '-b' command line option
> * pin_user_pages_fast(): via the '-a' command line option
> 
> Also, add an option for clarity: '-u' for what is now (still) the
> default choice: get_user_pages_fast().
> 
> Also, for the three commands that set FOLL_PIN, verify that the pages
> really are dma-pinned, via the new is_dma_pinned() routine.
> Those commands are:
> 
>     PIN_FAST_BENCHMARK     : calls pin_user_pages_fast()
>     PIN_LONGTERM_BENCHMARK : calls pin_longterm_pages()
>     PIN_BENCHMARK          : calls pin_user_pages()
> 
> In between the calls to pin_*() and put_user_pages(),
> check each page: if page_dma_pinned() returns false, then
> WARN and return.
> 
> Do this outside of the benchmark timestamps, so that it doesn't
> affect reported times.
> 
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Reviewed-by: Ira Weiny <ira.weiny@intel.com>

> ---
>  mm/gup_benchmark.c                         | 73 ++++++++++++++++++++--
>  tools/testing/selftests/vm/gup_benchmark.c | 23 ++++++-
>  2 files changed, 90 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
> index 7fc44d25eca7..8f980d91dbf5 100644
> --- a/mm/gup_benchmark.c
> +++ b/mm/gup_benchmark.c
> @@ -8,6 +8,9 @@
>  #define GUP_FAST_BENCHMARK	_IOWR('g', 1, struct gup_benchmark)
>  #define GUP_LONGTERM_BENCHMARK	_IOWR('g', 2, struct gup_benchmark)
>  #define GUP_BENCHMARK		_IOWR('g', 3, struct gup_benchmark)
> +#define PIN_FAST_BENCHMARK	_IOWR('g', 4, struct gup_benchmark)
> +#define PIN_LONGTERM_BENCHMARK	_IOWR('g', 5, struct gup_benchmark)
> +#define PIN_BENCHMARK		_IOWR('g', 6, struct gup_benchmark)
>  
>  struct gup_benchmark {
>  	__u64 get_delta_usec;
> @@ -19,6 +22,44 @@ struct gup_benchmark {
>  	__u64 expansion[10];	/* For future use */
>  };
>  
> +static void put_back_pages(int cmd, struct page **pages, unsigned long nr_pages)
> +{
> +	int i;
> +
> +	switch (cmd) {
> +	case GUP_FAST_BENCHMARK:
> +	case GUP_LONGTERM_BENCHMARK:
> +	case GUP_BENCHMARK:
> +		for (i = 0; i < nr_pages; i++)
> +			put_page(pages[i]);
> +		break;
> +
> +	case PIN_FAST_BENCHMARK:
> +	case PIN_LONGTERM_BENCHMARK:
> +	case PIN_BENCHMARK:
> +		put_user_pages(pages, nr_pages);
> +		break;
> +	}
> +}
> +
> +static void verify_dma_pinned(int cmd, struct page **pages,
> +			      unsigned long nr_pages)
> +{
> +	int i;
> +
> +	switch (cmd) {
> +	case PIN_FAST_BENCHMARK:
> +	case PIN_LONGTERM_BENCHMARK:
> +	case PIN_BENCHMARK:
> +		for (i = 0; i < nr_pages; i++) {
> +			if (WARN(!page_dma_pinned(pages[i]),
> +				 "pages[%d] is NOT dma-pinned\n", i))
> +				break;
> +		}
> +		break;
> +	}
> +}
> +
>  static int __gup_benchmark_ioctl(unsigned int cmd,
>  		struct gup_benchmark *gup)
>  {
> @@ -65,6 +106,18 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  			nr = get_user_pages(addr, nr, gup->flags, pages + i,
>  					    NULL);
>  			break;
> +		case PIN_FAST_BENCHMARK:
> +			nr = pin_user_pages_fast(addr, nr, gup->flags,
> +						 pages + i);
> +			break;
> +		case PIN_LONGTERM_BENCHMARK:
> +			nr = pin_longterm_pages(addr, nr, gup->flags, pages + i,
> +						NULL);
> +			break;
> +		case PIN_BENCHMARK:
> +			nr = pin_user_pages(addr, nr, gup->flags, pages + i,
> +					    NULL);
> +			break;
>  		default:
>  			return -1;
>  		}
> @@ -75,15 +128,22 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
>  	}
>  	end_time = ktime_get();
>  
> +	/* Shifting the meaning of nr_pages: now it is actual number pinned: */
> +	nr_pages = i;
> +
>  	gup->get_delta_usec = ktime_us_delta(end_time, start_time);
>  	gup->size = addr - gup->addr;
>  
> +	/*
> +	 * Take an un-benchmark-timed moment to verify DMA pinned
> +	 * state: print a warning if any non-dma-pinned pages are found:
> +	 */
> +	verify_dma_pinned(cmd, pages, nr_pages);
> +
>  	start_time = ktime_get();
> -	for (i = 0; i < nr_pages; i++) {
> -		if (!pages[i])
> -			break;
> -		put_page(pages[i]);
> -	}
> +
> +	put_back_pages(cmd, pages, nr_pages);
> +
>  	end_time = ktime_get();
>  	gup->put_delta_usec = ktime_us_delta(end_time, start_time);
>  
> @@ -101,6 +161,9 @@ static long gup_benchmark_ioctl(struct file *filep, unsigned int cmd,
>  	case GUP_FAST_BENCHMARK:
>  	case GUP_LONGTERM_BENCHMARK:
>  	case GUP_BENCHMARK:
> +	case PIN_FAST_BENCHMARK:
> +	case PIN_LONGTERM_BENCHMARK:
> +	case PIN_BENCHMARK:
>  		break;
>  	default:
>  		return -EINVAL;
> diff --git a/tools/testing/selftests/vm/gup_benchmark.c b/tools/testing/selftests/vm/gup_benchmark.c
> index 389327e9b30a..03928e47a86f 100644
> --- a/tools/testing/selftests/vm/gup_benchmark.c
> +++ b/tools/testing/selftests/vm/gup_benchmark.c
> @@ -18,6 +18,15 @@
>  #define GUP_LONGTERM_BENCHMARK	_IOWR('g', 2, struct gup_benchmark)
>  #define GUP_BENCHMARK		_IOWR('g', 3, struct gup_benchmark)
>  
> +/*
> + * Similar to above, but use FOLL_PIN instead of FOLL_GET. This is done
> + * by calling pin_user_pages_fast(), pin_longterm_pages(), and pin_user_pages(),
> + * respectively.
> + */
> +#define PIN_FAST_BENCHMARK	_IOWR('g', 4, struct gup_benchmark)
> +#define PIN_LONGTERM_BENCHMARK	_IOWR('g', 5, struct gup_benchmark)
> +#define PIN_BENCHMARK		_IOWR('g', 6, struct gup_benchmark)
> +
>  /* Just the flags we need, copied from mm.h: */
>  #define FOLL_WRITE	0x01	/* check pte is writable */
>  
> @@ -40,8 +49,17 @@ int main(int argc, char **argv)
>  	char *file = "/dev/zero";
>  	char *p;
>  
> -	while ((opt = getopt(argc, argv, "m:r:n:f:tTLUwSH")) != -1) {
> +	while ((opt = getopt(argc, argv, "m:r:n:f:abctTLUuwSH")) != -1) {
>  		switch (opt) {
> +		case 'a':
> +			cmd = PIN_FAST_BENCHMARK;
> +			break;
> +		case 'b':
> +			cmd = PIN_LONGTERM_BENCHMARK;
> +			break;
> +		case 'c':
> +			cmd = PIN_BENCHMARK;
> +			break;
>  		case 'm':
>  			size = atoi(optarg) * MB;
>  			break;
> @@ -63,6 +81,9 @@ int main(int argc, char **argv)
>  		case 'U':
>  			cmd = GUP_BENCHMARK;
>  			break;
> +		case 'u':
> +			cmd = GUP_FAST_BENCHMARK;
> +			break;
>  		case 'w':
>  			write = 1;
>  			break;
> -- 
> 2.24.0
>