drm/xe: Adjust long-running workload timeslices to reasonable values

commit 6f0f404 upstream.

A 10ms timeslice for long-running workloads is far too long and causes
significant jitter in benchmarks when the system is shared. Adjust the
value to 5ms for preempt-fencing VMs, as the resume step there is quite
costly as memory is moved around, and set it to zero for pagefault VMs,
since switching back to pagefault mode after dma-fence mode is
relatively fast.

Also change min_run_period_ms to 'unsiged int' type rather than 's64' as
only positive values make sense.

Fixes: dd08ebf ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Cc: stable@vger.kernel.org
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Link: https://patch.msgid.link/20251212182847.1683222-2-matthew.brost@intel.com
(cherry picked from commit 33a5abd)
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: mbrost05

drivers/gpu/drm/xe/xe_vm.c

@@ -1481,7 +1481,10 @@ struct xe_vm *xe_vm_create(struct xe_device *xe, u32 flags, struct xe_file *xef)
 	INIT_WORK(&vm->destroy_work, vm_destroy_work_func);
 
 	INIT_LIST_HEAD(&vm->preempt.exec_queues);
-	vm->preempt.min_run_period_ms = 10;	/* FIXME: Wire up to uAPI */
+	if (flags & XE_VM_FLAG_FAULT_MODE)
+		vm->preempt.min_run_period_ms = 0;
+	else
+		vm->preempt.min_run_period_ms = 5;
 
 	for_each_tile(tile, xe, id)
 		xe_range_fence_tree_init(&vm->rftree[id]);

drivers/gpu/drm/xe/xe_vm_types.h

@@ -268,7 +268,7 @@ struct xe_vm {
 		 * @min_run_period_ms: The minimum run period before preempting
 		 * an engine again
 		 */
-		s64 min_run_period_ms;
+		unsigned int min_run_period_ms;
 		/** @exec_queues: list of exec queues attached to this VM */
 		struct list_head exec_queues;
 		/** @num_exec_queues: number exec queues attached to this VM */