[igt-dev] [PATCH igt] igt/gem_exec_schedule: Trim max number of contexts used

[Antonio Argenziano]

On 13/02/18 01:26, Chris Wilson wrote:
> icl offers a much reduced context space, and in its simplest setup we
> cannot allocate one context per priority level, so trim the number and
> reuse the same context for multiple priority requests.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   tests/gem_exec_schedule.c | 38 +++++++++++++++++++++++---------------
>   1 file changed, 23 insertions(+), 15 deletions(-)
> 
> diff --git a/tests/gem_exec_schedule.c b/tests/gem_exec_schedule.c
> index 05f7ae38..ec02d994 100644
> --- a/tests/gem_exec_schedule.c
> +++ b/tests/gem_exec_schedule.c
> @@ -43,6 +43,8 @@
>   #define BUSY_QLEN 8
>   #define MAX_ELSP_QLEN 16
>   
> +#define MAX_CONTEXTS 256
> +
>   IGT_TEST_DESCRIPTION("Check that we can control the order of execution");
>   
>   static void store_dword(int fd, uint32_t ctx, unsigned ring,
> @@ -556,8 +558,8 @@ static void preemptive_hang(int fd, unsigned ring)
>   static void deep(int fd, unsigned ring)
>   {
>   #define XS 8
> -	const unsigned int nctx = MAX_PRIO - MIN_PRIO;
> -	const unsigned size = ALIGN(4*nctx, 4096);
> +	const unsigned int nreq = MAX_PRIO - MIN_PRIO;
> +	const unsigned size = ALIGN(4*nreq, 4096);
>   	struct timespec tv = {};
>   	struct cork cork;
>   	uint32_t result, dep[XS];
> @@ -565,10 +567,9 @@ static void deep(int fd, unsigned ring)
>   	uint32_t *ptr;
>   	uint32_t *ctx;
>   
> -	ctx = malloc(sizeof(*ctx) * nctx);
> -	for (int n = 0; n < nctx; n++) {
> +	ctx = malloc(sizeof(*ctx) * MAX_CONTEXTS);
> +	for (int n = 0; n < MAX_CONTEXTS; n++) {
>   		ctx[n] = gem_context_create(fd);
> -		gem_context_set_priority(fd, ctx[n], MAX_PRIO - nctx + n);
>   	}
>   
>   	result = gem_create(fd, size);
> @@ -592,7 +593,7 @@ static void deep(int fd, unsigned ring)
>   		execbuf.buffers_ptr = to_user_pointer(obj);
>   		execbuf.buffer_count = XS + 2;
>   		execbuf.flags = ring;
> -		for (int n = 0; n < nctx; n++) {
> +		for (int n = 0; n < MAX_CONTEXTS; n++) {
>   			execbuf.rsvd1 = ctx[n];
>   			gem_execbuf(fd, &execbuf);
>   		}
> @@ -603,22 +604,29 @@ static void deep(int fd, unsigned ring)
>   	plug(fd, &cork);
>   
>   	/* Create a deep dependency chain, with a few branches */
> -	for (int n = 0; n < nctx && igt_seconds_elapsed(&tv) < 8; n++)
> +	for (int n = 0; n < nreq && igt_seconds_elapsed(&tv) < 8; n++) {
> +		uint32_t context = ctx[n % MAX_CONTEXTS];

Doesn't this introduce some intra-context dependency we didn't have 
before? Do we care?

Thanks,
Antonio