Re: [PATCH i-g-t v5] tests/gem_mmap_gtt: add huge BO test

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 04/14/2015 12:14 PM, Joonas Lahtinen wrote:
> Add a straightforward test that allocates a BO that is bigger than
> (by 1 page currently) the mappable aperture, tests mmap access to it
> by CPU directly and through GTT in sequence.
>
> Currently it is expected for the GTT access to gracefully fail as
> all objects are attempted to get pinned to GTT completely for mmap
> access. Once the partial view support is merged to kernel, the test
> should pass for all parts.
>
> v2:
> - Corrected BO domain handling (Chris Wilson)
> - Check again after GTT access for added paranoia (Chris Wilson)
>
> v3:
> - Avoid flush by using pread (Chris Wilson)
> - Free gtt_pattern buffer too.
>
> v4:
> - Add more comments (Tvrtko Ursulin)
> - Use igt_require (Tvrtko Ursulin)
>
> v5:
> - Remove wrong message from igt_require_f (Tvrtko Ursulin)
> - After digging deeper to it, just igt_assert that the CPU
>    mapping needs to succeed.
>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> ---
>   tests/gem_mmap_gtt.c | 106 +++++++++++++++++++++++++++++++++++++++++++++++++++
>   1 file changed, 106 insertions(+)
>
> diff --git a/tests/gem_mmap_gtt.c b/tests/gem_mmap_gtt.c
> index 115e398..487eecf 100644
> --- a/tests/gem_mmap_gtt.c
> +++ b/tests/gem_mmap_gtt.c
> @@ -41,6 +41,10 @@
>   #include "drmtest.h"
>   #include "igt_debugfs.h"
>
> +#ifndef PAGE_SIZE
> +#define PAGE_SIZE 4096
> +#endif
> +
>   static int OBJECT_SIZE = 16*1024*1024;
>
>   static void
> @@ -55,6 +59,20 @@ set_domain_cpu(int fd, uint32_t handle)
>   	gem_set_domain(fd, handle, I915_GEM_DOMAIN_CPU, I915_GEM_DOMAIN_CPU);
>   }
>
> +static void
> +pread_bo(int fd, int handle, void *buf, int offset, int size)
> +{
> +	struct drm_i915_gem_pread gem_pread;
> +
> +	memset(&gem_pread, 0, sizeof(gem_pread));
> +	gem_pread.handle = handle;
> +	gem_pread.data_ptr = (uintptr_t)buf;
> +	gem_pread.size = size;
> +	gem_pread.offset = offset;
> +
> +	igt_assert(ioctl(fd, DRM_IOCTL_I915_GEM_PREAD, &gem_pread) == 0);
> +}
> +
>   static void *
>   mmap_bo(int fd, uint32_t handle)
>   {
> @@ -265,6 +283,92 @@ test_write_gtt(int fd)
>   }
>
>   static void
> +test_huge_bo(int fd)
> +{
> +	uint32_t bo;
> +	char *ptr_cpu;
> +	char *ptr_gtt;
> +	char *cpu_pattern;
> +	char *gtt_pattern;
> +	uint64_t mappable_aperture_pages = gem_mappable_aperture_size() /
> +					   PAGE_SIZE;
> +	uint64_t huge_object_size = (mappable_aperture_pages + 1) * PAGE_SIZE;
> +	uint64_t last_offset = huge_object_size - PAGE_SIZE;
> +
> +	cpu_pattern = malloc(PAGE_SIZE);
> +	gtt_pattern = malloc(PAGE_SIZE);
> +	igt_assert(cpu_pattern && gtt_pattern);
> +	memset(cpu_pattern,  0xaa, PAGE_SIZE);
> +	memset(gtt_pattern, ~0xaa, PAGE_SIZE);
> +
> +	bo = gem_create(fd, huge_object_size);
> +
> +	/* Obtain CPU mapping for the object. */
> +	ptr_cpu = gem_mmap__cpu(fd, bo, 0, huge_object_size,
> +				PROT_READ | PROT_WRITE);
> +	igt_assert(ptr_cpu);
> +
> +	set_domain_cpu(fd, bo);
> +
> +	/* Write first page through the mapping and assert reading it back
> +	 * works. */
> +	memcpy(ptr_cpu, cpu_pattern, PAGE_SIZE);
> +	igt_assert(memcmp(ptr_cpu, cpu_pattern, PAGE_SIZE) == 0);
> +
> +	/* Write last page through the mapping and assert reading it back
> +	 * works. */
> +	memcpy(ptr_cpu + last_offset, cpu_pattern, PAGE_SIZE);
> +	igt_assert(memcmp(ptr_cpu + last_offset, cpu_pattern, PAGE_SIZE) == 0);
> +
> +	/* Cross check that accessing two simultaneous pages works. */
> +	igt_assert(memcmp(ptr_cpu, ptr_cpu + last_offset, PAGE_SIZE) == 0);
> +
> +	munmap(ptr_cpu, huge_object_size);
> +	ptr_cpu = NULL;
> +
> +	/* Obtain mapping for the object through GTT. */
> +	ptr_gtt = gem_mmap__gtt(fd, bo, huge_object_size,
> +			        PROT_READ | PROT_WRITE);
> +	igt_require_f(ptr_gtt, "Huge BO GTT mapping not supported.\n");
> +
> +	set_domain_gtt(fd, bo);
> +
> +	/* Access through GTT should still provide the CPU written values. */
> +	igt_assert(memcmp(ptr_gtt              , cpu_pattern, PAGE_SIZE) == 0);
> +	igt_assert(memcmp(ptr_gtt + last_offset, cpu_pattern, PAGE_SIZE) == 0);
> +
> +	/* Try replacing first page through GTT mapping and make sure other page
> +	 * stays intact. */
> +	memcpy(ptr_gtt, gtt_pattern, PAGE_SIZE);
> +	igt_assert(memcmp(ptr_gtt              , gtt_pattern, PAGE_SIZE) == 0);
> +	igt_assert(memcmp(ptr_gtt + last_offset, cpu_pattern, PAGE_SIZE) == 0);
> +
> +	/* And make sure that after writing, both pages contain what they
> +	 * should.*/
> +	memcpy(ptr_gtt + last_offset, gtt_pattern, PAGE_SIZE);
> +	igt_assert(memcmp(ptr_gtt              , gtt_pattern, PAGE_SIZE) == 0);
> +	igt_assert(memcmp(ptr_gtt + last_offset, gtt_pattern, PAGE_SIZE) == 0);
> +
> +	munmap(ptr_gtt, huge_object_size);
> +	ptr_gtt = NULL;
> +
> +	/* Verify the page contents after GTT writes by reading without mapping.
> +	 * Mapping to CPU domain is avoided not to cause a huge flush.
> +	 */
> +	pread_bo(fd, bo, cpu_pattern, 0, PAGE_SIZE);
> +	igt_assert(memcmp(cpu_pattern, gtt_pattern, PAGE_SIZE) == 0);
> +
> +	memset(cpu_pattern, 0x00, PAGE_SIZE);
> +
> +	pread_bo(fd, bo, cpu_pattern, last_offset, PAGE_SIZE);
> +	igt_assert(memcmp(cpu_pattern, gtt_pattern, PAGE_SIZE) == 0);
> +out:
> +	gem_close(fd, bo);
> +	free(cpu_pattern);
> +	free(gtt_pattern);
> +}
> +
> +static void
>   test_read(int fd)
>   {
>   	void *dst;
> @@ -402,6 +506,8 @@ igt_main
>   		run_without_prefault(fd, test_write_gtt);
>   	igt_subtest("write-cpu-read-gtt")
>   		test_write_cpu_read_gtt(fd);
> +	igt_subtest("huge-bo")
> +		test_huge_bo(fd);
>
>   	igt_fixture
>   		close(fd);
>

I suspect in the future you may want to create a dedicated test for 
partial views since there will be many more specific test cases, but for 
now:

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko

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