[igt-dev] [Intel-gfx] [PATCH i-g-t] i915/gem_ctx_param: Keep the engine active while peeking at vm layout

[Summers, Stuart]

On Sun, 2019-11-24 at 11:27 +0000, Chris Wilson wrote:
> The implicit soft-pinning we use to probe the vm layout using
> execbuf,
> depends on the batch remaining active (not retired) between execbufs.
> Naturally, if the background retire worker runs the batch is retired
> and
> the implicit soft-pinning is free to use a fresh address.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>  tests/i915/gem_ctx_param.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
> 
> diff --git a/tests/i915/gem_ctx_param.c b/tests/i915/gem_ctx_param.c
> index bd1ee3996..63e0db38d 100644
> --- a/tests/i915/gem_ctx_param.c
> +++ b/tests/i915/gem_ctx_param.c
> @@ -161,6 +161,7 @@ static void test_vm(int i915)
>  		.param = I915_CONTEXT_PARAM_VM,
>  	};
>  	uint32_t parent, child;
> +	igt_spin_t *spin;
>  
>  	/*
>  	 * Proving 2 contexts share the same GTT is quite tricky as we
> have no
> @@ -177,6 +178,15 @@ static void test_vm(int i915)
>  	parent = gem_context_create(i915);
>  	child = gem_context_create(i915);
>  
> +	/* Create a background spinner to keep the engines busy */
> +	spin = igt_spin_new(i915);
> +	for (int i = 0; i < 16; i++) {

Why 16 here?

> +		spin->execbuf.rsvd1 = gem_context_create(i915);
> +		gem_context_set_priority(i915, spin->execbuf.rsvd1,
> 1023);

Can you make this 1023 a macro?

Thanks,
Stuart

> +		gem_execbuf(i915, &spin->execbuf);
> +		gem_context_destroy(i915, spin->execbuf.rsvd1);
> +	}
> +
>  	/* Using implicit soft-pinning */
>  	eb.rsvd1 = parent;
>  	batch.offset = nonzero_offset;
> @@ -226,6 +236,7 @@ static void test_vm(int i915)
>  	gem_context_destroy(i915, child);
>  	gem_vm_destroy(i915, arg.value);
>  
> +	igt_spin_free(i915, spin);
>  	gem_sync(i915, batch.handle);
>  	gem_close(i915, batch.handle);
>  }
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