Commit df8c3781 authored by Matthew Brost's avatar Matthew Brost Committed by Lucas De Marchi
Browse files

drm/gpusvm: Add timeslicing support to GPU SVM 



Add timeslicing support to GPU SVM which will guarantee the GPU a
minimum execution time on piece of physical memory before migration back
to CPU. Intended to implement strict migration policies which require
memory to be in a certain placement for correct execution.

Required for shared CPU and GPU atomics on certain devices.

Fixes: 99624bdf ("drm/gpusvm: Add support for GPU Shared Virtual Memory")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarMatthew Brost <matthew.brost@intel.com>
Reviewed-by: default avatarHimal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Link: https://lore.kernel.org/r/20250512135500.1405019-4-matthew.brost@intel.com


(cherry picked from commit 8dc1812b)
Signed-off-by: default avatarLucas De Marchi <lucas.demarchi@intel.com>
parent 794f5493

drivers/gpu/drm/drm_gpusvm.c

+9 −0
Original line number Diff line number Diff line
@@ -1783,6 +1783,8 @@ int drm_gpusvm_migrate_to_devmem(struct drm_gpusvm *gpusvm, 
		goto err_finalize;



	/* Upon success bind devmem allocation to range and zdd */

	devmem_allocation->timeslice_expiration = get_jiffies_64() +

		msecs_to_jiffies(ctx->timeslice_ms);

	zdd->devmem_allocation = devmem_allocation;	/* Owns ref */



err_finalize:
@@ -2003,6 +2005,13 @@ static int __drm_gpusvm_migrate_to_ram(struct vm_area_struct *vas, 
	void *buf;

	int i, err = 0;



	if (page) {

		zdd = page->zone_device_data;

		if (time_before64(get_jiffies_64(),

				  zdd->devmem_allocation->timeslice_expiration))

			return 0;

	}



	start = ALIGN_DOWN(fault_addr, size);

	end = ALIGN(fault_addr + 1, size);

include/drm/drm_gpusvm.h

+5 −0
Original line number Diff line number Diff line
@@ -89,6 +89,7 @@ struct drm_gpusvm_devmem_ops { 
 * @ops: Pointer to the operations structure for GPU SVM device memory

 * @dpagemap: The struct drm_pagemap of the pages this allocation belongs to.

 * @size: Size of device memory allocation

 * @timeslice_expiration: Timeslice expiration in jiffies

 */

struct drm_gpusvm_devmem {

	struct device *dev;
@@ -97,6 +98,7 @@ struct drm_gpusvm_devmem { 
	const struct drm_gpusvm_devmem_ops *ops;

	struct drm_pagemap *dpagemap;

	size_t size;

	u64 timeslice_expiration;

};



/**
@@ -295,6 +297,8 @@ struct drm_gpusvm { 
 * @check_pages_threshold: Check CPU pages for present if chunk is less than or

 *                         equal to threshold. If not present, reduce chunk

 *                         size.

 * @timeslice_ms: The timeslice MS which in minimum time a piece of memory

 *		  remains with either exclusive GPU or CPU access.

 * @in_notifier: entering from a MMU notifier

 * @read_only: operating on read-only memory

 * @devmem_possible: possible to use device memory
@@ -304,6 +308,7 @@ struct drm_gpusvm { 
 */

struct drm_gpusvm_ctx {

	unsigned long check_pages_threshold;

	unsigned long timeslice_ms;

	unsigned int in_notifier :1;

	unsigned int read_only :1;

	unsigned int devmem_possible :1;