Re: [PATCH 2/2] tests/intel/xe_vm: Always have at least 2 pages bound in munmap hammer sections

["Randhawa, Jagmeet" <jagmeet.randhawa@intel.com>]

On 4/11/2024 9:18 PM, Matthew Brost wrote:
> If the prefetch buffer is 2k or larger the munmap hammer sections will
> prefetch the next page, if the page is unbound a fault will occur.
> Account for larger prefetchs by always having at least 2 pages bound for
> the hammer thread.
>
> v2:
>   - Missed table entry
> v3:
>   - Don't modify mmap section (Jonathan)
>   - Add assert to ensure no prefetch overrun (Matt Auld)
>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   tests/intel/xe_vm.c | 13 +++++++++----
>   1 file changed, 9 insertions(+), 4 deletions(-)
>
> diff --git a/tests/intel/xe_vm.c b/tests/intel/xe_vm.c
> index bd4973cc38..13cca27520 100644
> --- a/tests/intel/xe_vm.c
> +++ b/tests/intel/xe_vm.c
> @@ -1263,6 +1263,11 @@ test_munmap_style_unbind(int fd, struct drm_xe_engine_class_instance *eci,
>   	int exit = 0;
>   	int n_page_per_2mb = 0x200000 / xe_get_default_alignment(fd);
>   
> +	/* Ensure prefetch will not fetch an unmapped page */
> +	if (flags & MAP_FLAG_HAMMER_FIRST_PAGE)
> +		igt_assert(unbind_n_page_offset * 0x1000 >
> +			   xe_cs_prefetch_size(fd));
> +
>   	if (flags & MAP_FLAG_LARGE_PAGE) {
>   		bo_n_pages *= n_page_per_2mb;
>   		unbind_n_pages *= n_page_per_2mb;
> @@ -1843,12 +1848,12 @@ igt_main
>   		{ "all", 4, 2, 0, 4, 0 },
>   		{ "one-partial", 4, 1, 1, 2, 0 },
>   		{ "either-side-partial", 4, 2, 1, 2, 0 },
> -		{ "either-side-partial-hammer", 4, 2, 1, 2,
> +		{ "either-side-partial-hammer", 6, 2, 2, 2,
>   			MAP_FLAG_HAMMER_FIRST_PAGE },
> -		{ "either-side-partial-split-page-hammer", 4, 2, 1, 2,
> +		{ "either-side-partial-split-page-hammer", 6, 2, 2, 2,
>   			MAP_FLAG_HAMMER_FIRST_PAGE |
>   			MAP_FLAG_LARGE_PAGE },
> -		{ "either-side-partial-large-page-hammer", 4, 2, 1, 2,
> +		{ "either-side-partial-large-page-hammer", 6, 2, 2, 2,
>   			MAP_FLAG_HAMMER_FIRST_PAGE |
>   			MAP_FLAG_LARGE_PAGE |
>   			MAP_FLAG_LARGE_PAGE_NO_SPLIT },
> @@ -1857,7 +1862,7 @@ igt_main
>   		{ "front", 4, 2, 1, 3, 0 },
>   		{ "many-all", 4 * 8, 2 * 8, 0 * 8, 4 * 8, 0 },
>   		{ "many-either-side-partial", 4 * 8, 2 * 8, 1, 4 * 8 - 2, 0 },
> -		{ "many-either-side-partial-hammer", 4 * 8, 2 * 8, 1, 4 * 8 - 2,
> +		{ "many-either-side-partial-hammer", 4 * 8, 2 * 8, 2, 4 * 8 - 4,
>   			MAP_FLAG_HAMMER_FIRST_PAGE },
>   		{ "many-either-side-full", 4 * 8, 4 * 8, 1 * 8, 2 * 8, 0 },
>   		{ "many-end", 4 * 8, 4, 0 * 8, 3 * 8 + 2, 0 },
Reviewed-by: Jagmeet Randhawa <jagmeet.randhawa@intel.com>