Re: [PATCH i-g-t 1/2] benchmarks/gem_wsim: add explicit VM create/assign steps

[Adam Miszczak <adam.miszczak@linux.intel.com>]

On 7/14/2026 5:12 PM, Marcin Bernatowicz wrote:
> Add explicit VM management to workload descriptors so Xe runs can model
> VM topology directly.
>
> Introduce two new descriptor steps:
> - V.N     create VM id N (1-based)
> - v.N.M   assign VM N to context M
>
> Implementation details:
> - Add VM_CREATE and CTX_VM step types and vm_id storage in w_step.
> - Parse V/v syntax with validation and clear error messages.
> - Add allocate_vms() pre-scan to size and allocate vm_list from V steps.
> - Update xe_prepare_contexts() to support explicit VM mode:
>    - create all explicit VMs
>    - default contexts to VM 0
>    - apply per-context VM assignments from v steps
>    - retain implicit single-VM fallback when no V steps are present
> - Make get_vm() use per-context VM linkage.
>
> Documentation:
> - Add VM management step documentation into benchmarks/wsim/README.
>
> This keeps i915 behavior unchanged while enabling explicit VM topology
> control for Xe workloads.
>
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> Signed-off-by: Marcin Bernatowicz <marcin.bernatowicz@linux.intel.com>
> Cc: Adam Miszczak <adam.miszczak@linux.intel.com>
> Cc: Lukasz Laguna <lukasz.laguna@intel.com>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
> ---
>   benchmarks/gem_wsim.c  | 143 +++++++++++++++++++++++++++++++++++++----
>   benchmarks/wsim/README |  19 ++++++
>   2 files changed, 150 insertions(+), 12 deletions(-)
>
> diff --git a/benchmarks/gem_wsim.c b/benchmarks/gem_wsim.c
> index 8be44d0c8..b3c46772f 100644
> --- a/benchmarks/gem_wsim.c
> +++ b/benchmarks/gem_wsim.c
> @@ -130,6 +130,8 @@ enum w_type {
>   	TERMINATE,
>   	SSEU,
>   	WORKINGSET,
> +	VM_CREATE,
> +	CTX_VM,
>   };
>   
>   struct dep_entry {
> @@ -210,6 +212,7 @@ struct w_step {
>   		struct bond bond;
>   		int sseu;
>   		struct working_set working_set;
> +		int vm_id;
>   	};
>   
>   	/* Implementation details */
> @@ -241,6 +244,7 @@ struct w_step {
>   
>   struct vm {
>   	uint32_t id;
> +	bool declared;
>   	bool compute_mode;
>   	uint64_t ahnd;
>   };
> @@ -1240,6 +1244,55 @@ parse_workload(struct w_arg *arg, unsigned int flags, double scale_dur,
>   
>   				step.type = WORKINGSET;
>   				goto add_step;
> +			} else if (!strcmp(field, "V")) {
> +				/*
> +				 * V.N  - create VM with id N (xe only, ignored on i915)
> +				 * VM ids are 1-based in the descriptor.
> +				 */
> +				field = strtok_r(fstart, ".", &fctx);
> +				check_arg(!field, "Missing VM id at step %u!\n",
> +					  nr_steps);
> +				tmp = atoi(field);
> +				check_arg(tmp <= 0, "Invalid VM id at step %u!\n",
> +					  nr_steps);
> +				step.vm_id = tmp;
> +				step.type = VM_CREATE;
> +				goto add_step;
> +			} else if (!strcmp(field, "v")) {
> +				/*
> +				 * v.N.M  - assign VM N to ctx M
> +				 * (xe only, ignored on i915)
> +				 */
> +				unsigned int nr = 0;
> +				int vm = 0, ctx_id = 0;
> +
> +				while ((field = strtok_r(fstart, ".", &fctx))) {
> +					fstart = NULL;
> +					tmp = atoi(field);
> +					if (nr == 0) {
> +						check_arg(tmp <= 0,
> +							  "Invalid VM id at step %u!\n",
> +							  nr_steps);
> +						vm = tmp;
> +					} else if (nr == 1) {
> +						check_arg(tmp <= 0,
> +							  "Invalid ctx id at step %u!\n",
> +							  nr_steps);
> +						ctx_id = tmp;
> +					} else {
> +						check_arg(1,
> +							  "Too many fields in v step at step %u!\n",
> +							  nr_steps);
> +					}
> +					nr++;
> +				}
> +				check_arg(nr != 2,
> +					  "v step requires VM id and ctx id at step %u!\n",
> +					  nr_steps);
> +				step.vm_id = vm;
> +				step.context = ctx_id;
> +				step.type = CTX_VM;
> +				goto add_step;
>   			}
>   
>   			if (!field) {
> @@ -1665,6 +1718,14 @@ xe_get_eq(struct workload *wrk, const struct w_step *w)
>   static struct vm *
>   get_vm(struct workload *wrk, const struct w_step *w)
>   {
> +	struct ctx *ctx = __get_ctx(wrk, w);
> +
> +	/* If the ctx has been linked to an explicit VM, use it; otherwise
> +	 * fall back to the implicit single vm_list[0].
> +	 */
> +	if (ctx->vm)
> +		return ctx->vm;
> +
>   	return wrk->vm_list;
>   }
>   
> @@ -2087,6 +2148,33 @@ static void xe_exec_queue_create_(struct ctx *ctx, struct xe_exec_queue *eq)
>   	eq->id = create.exec_queue_id;
>   }
>   
> +static void allocate_vms(struct workload *wrk)
> +{
> +	int max_vm = 0;
> +	struct w_step *w;
> +
> +	/*
> +	 * Slot 0 is always the implicit/default VM. Descriptor VM ids are
> +	 * 1-based and map directly to vm_list[N] for explicit V.N steps.
> +	 */
> +	for_each_w_step(w, wrk) {
> +		if (w->type != VM_CREATE)
> +			continue;
> +		if (w->vm_id > max_vm)
> +			max_vm = w->vm_id;
> +	}
> +
> +	wrk->nr_vms = max_vm + 1;
> +	wrk->vm_list = calloc(wrk->nr_vms, sizeof(*wrk->vm_list));
> +	igt_assert(wrk->vm_list);
> +
> +	for_each_w_step(w, wrk) {
> +		if (w->type == VM_CREATE)
> +			/* Mark only explicitly declared VMs; slot 0 stays implicit. */
> +			wrk->vm_list[w->vm_id].declared = true;
> +	}
> +}
> +
>   static void allocate_contexts(unsigned int id, struct workload *wrk)
>   {
>   	int max_ctx = -1;
> @@ -2094,13 +2182,19 @@ static void allocate_contexts(unsigned int id, struct workload *wrk)
>   
>   	/*
>   	 * Pre-scan workload steps to allocate context list storage.
> +	 * Skip VM management steps whose context field is unused.
>   	 */
>   	for_each_w_step(w, wrk) {
> -		int ctx = w->context + 1;
> +		int ctx;
>   		int delta;
>   
>   		w->wrk = wrk;
>   
> +		if (w->type == VM_CREATE)
> +			continue;
> +
> +		ctx = w->context + 1;
> +
>   		if (ctx <= max_ctx)
>   			continue;
>   
> @@ -2333,18 +2427,38 @@ static int xe_prepare_contexts(unsigned int id, struct workload *wrk)
>   	struct ctx *ctx;
>   	unsigned int i;
>   
> -	/* shortcut, create one vm */
> -	wrk->nr_vms = 1;
> -	wrk->vm_list = calloc(wrk->nr_vms, sizeof(struct vm));
> -	igt_assert(wrk->vm_list);
> -	wrk->vm_list->compute_mode = false;
> -	xe_vm_create_(wrk->vm_list);
> -	wrk->vm_list->ahnd = intel_allocator_open(fd, wrk->vm_list->id,
> -						  INTEL_ALLOCATOR_RELOC);
> +	/* Slot 0 is the implicit/default VM. */
> +	xe_vm_create_(&wrk->vm_list[0]);
> +	wrk->vm_list[0].ahnd = intel_allocator_open(fd, wrk->vm_list[0].id,
> +						    INTEL_ALLOCATOR_RELOC);
> +
> +	for (i = 1; i < wrk->nr_vms; i++) {
> +		if (!wrk->vm_list[i].declared)
> +			continue;
> +
> +		xe_vm_create_(&wrk->vm_list[i]);
> +		wrk->vm_list[i].ahnd =
> +			intel_allocator_open(fd, wrk->vm_list[i].id,
> +					     INTEL_ALLOCATOR_RELOC);
> +	}
> +
> +	/*
> +	 * Process CTX_VM steps to link each ctx to an explicit VM. Contexts
> +	 * without a v.N.M mapping remain on the implicit VM in slot 0.
> +	 */
> +	__for_each_ctx(ctx, wrk, ctx_idx)
> +		ctx->vm = &wrk->vm_list[0];
> +
> +	for_each_w_step(w, wrk) {
> +		if (w->type != CTX_VM)
> +			continue;
> +		igt_assert_lt((unsigned int)w->vm_id, wrk->nr_vms);
> +		igt_assert(wrk->vm_list[w->vm_id].declared);
> +		igt_assert_lt((unsigned int)w->context, wrk->nr_ctxs);
> +		wrk->ctx_list[w->context].vm = &wrk->vm_list[w->vm_id];
> +	}
>   
>   	__for_each_ctx(ctx, wrk, ctx_idx) {
> -		/* link with vm */
> -		ctx->vm = wrk->vm_list;
>   		for_each_w_step(w, wrk) {
>   			if (w->context != ctx_idx)
>   				continue;
> @@ -2537,6 +2651,9 @@ static int prepare_workload(unsigned int id, struct workload *wrk)
>   
>   	allocate_contexts(id, wrk);
>   
> +	if (is_xe)
> +		allocate_vms(wrk);
> +
>   	if (is_xe)
>   		ret = xe_prepare_contexts(id, wrk);
>   	else
> @@ -2857,7 +2974,9 @@ static void *run_workload(void *data)
>   				   w->type == ENGINE_MAP ||
>   				   w->type == LOAD_BALANCE ||
>   				   w->type == BOND ||
> -				   w->type == WORKINGSET) {
> +				   w->type == WORKINGSET ||
> +				   w->type == VM_CREATE ||
> +				   w->type == CTX_VM) {
>   				   /* No action for these at execution time. */
>   				continue;
>   			}
> diff --git a/benchmarks/wsim/README b/benchmarks/wsim/README
> index e43813335..909c1f039 100644
> --- a/benchmarks/wsim/README
> +++ b/benchmarks/wsim/README
> @@ -11,6 +11,8 @@ P|S|X.<uint>.<int>
>   d|p|s|t|q|a|T.<int>,...
>   b.<uint>.<str>[|<str>].<str>
>   w|W.<uint>.<str>[/<str>]...
> +V.<uint>
> +v.<uint>.<uint>
>   f
>   
>   For duration a range can be given from which a random value will be picked
> @@ -39,6 +41,11 @@ Additional workload steps are also supported:
>    'W' - Shared working set.
>    'X' - Context preemption control.
>   
> +VM management steps (Xe: active; i915: ignored):
> +
> + 'V' - Create VM with id N (V.N, VM ids are 1-based).
> + 'v' - Assign VM N to context/queue M (v.N.M).
> +
>   Engine ids: DEFAULT, RCS, BCS, VCS, VCS1, VCS2, VECS
>   
>   Example (leading spaces must not be present in the actual file):
> @@ -88,6 +95,18 @@ Batch durations can also be specified as infinite by using the '*' in the
>   duration field. Such batches must be ended by the terminate command ('T')
>   otherwise they will cause a GPU hang to be reported.
>   
> +VM Example:
> +
> +  V.1
> +  M.1.VCS
> +  v.1.1
> +  B.1
> +  1.VCS.1000.0.0
> +
> +Creates VM 1, configures context 1 with a VCS engine map, assigns context 1
> +to VM 1, enables load balancing for context 1, and runs a single 1ms VCS
> +batch.
> +
>   Xe and i915 differences
>   ------------------------
>   
Agree with Kamil, please at least once reference as VM (Virtual Memory) 
to avoid potential confusion with virtualization VM (Virtual Machine).
Other than that LGTM:
Reviewed-by: Adam Miszczak <adam.miszczak@linux.intel.com>

Regards,
Adam