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Commit 0839ccb8 authored by Keith Packard's avatar Keith Packard Committed by Ingo Molnar
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i915: use io-mapping interfaces instead of a variety of mapping kludges 



Impact: optimize/clean-up the IO mapping implementation of the i915 DRM driver

Switch the i915 device aperture mapping to the io-mapping interface, taking
advantage of the cleaner API to extend it across all of the mapping uses,
including both pwrite and relocation updates.

This dramatically improves performance on 64-bit kernels which were using
the same slow path as 32-bit non-HIGHMEM kernels prior to this patch.

Signed-off-by: default avatarKeith Packard <keithp@keithp.com>
Signed-off-by: default avatarEric Anholt <eric@anholt.net>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 9663f2e6

drivers/gpu/drm/i915/i915_drv.h

+3 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 
#define _I915_DRV_H_



#include "i915_reg.h"

#include <linux/io-mapping.h>



/* General customization:

 */
@@ -246,6 +247,8 @@ typedef struct drm_i915_private { 
	struct {

		struct drm_mm gtt_space;



		struct io_mapping *gtt_mapping;



		/**

		 * List of objects currently involved in rendering from the

		 * ringbuffer.

drivers/gpu/drm/i915/i915_gem.c

+80 −94
Original line number Diff line number Diff line
@@ -171,35 +171,50 @@ i915_gem_pread_ioctl(struct drm_device *dev, void *data, 
	return 0;

}



/*

 * Try to write quickly with an atomic kmap. Return true on success.

 *

 * If this fails (which includes a partial write), we'll redo the whole

 * thing with the slow version.

 *

 * This is a workaround for the low performance of iounmap (approximate

 * 10% cpu cost on normal 3D workloads).  kmap_atomic on HIGHMEM kernels

 * happens to let us map card memory without taking IPIs.  When the vmap

 * rework lands we should be able to dump this hack.

/* This is the fast write path which cannot handle

 * page faults in the source data

 */

static inline int fast_user_write(unsigned long pfn, char __user *user_data,

				  int l, int o)



static inline int

fast_user_write(struct io_mapping *mapping,

		loff_t page_base, int page_offset,

		char __user *user_data,

		int length)

{

#ifdef CONFIG_HIGHMEM

	unsigned long unwritten;

	char *vaddr_atomic;

	unsigned long unwritten;



	vaddr_atomic = kmap_atomic_pfn(pfn, KM_USER0);

#if WATCH_PWRITE

	DRM_INFO("pwrite i %d o %d l %d pfn %ld vaddr %p\n",

		 i, o, l, pfn, vaddr_atomic);

#endif

	unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + o, user_data, l);

	kunmap_atomic(vaddr_atomic, KM_USER0);

	return !unwritten;

#else

	vaddr_atomic = io_mapping_map_atomic_wc(mapping, page_base);

	unwritten = __copy_from_user_inatomic_nocache(vaddr_atomic + page_offset,

						      user_data, length);

	io_mapping_unmap_atomic(vaddr_atomic);

	if (unwritten)

		return -EFAULT;

	return 0;

}



/* Here's the write path which can sleep for

 * page faults

 */



static inline int

slow_user_write(struct io_mapping *mapping,

		loff_t page_base, int page_offset,

		char __user *user_data,

		int length)

{

	char __iomem *vaddr;

	unsigned long unwritten;



	vaddr = io_mapping_map_wc(mapping, page_base);

	if (vaddr == NULL)

		return -EFAULT;

	unwritten = __copy_from_user(vaddr + page_offset,

				     user_data, length);

	io_mapping_unmap(vaddr);

	if (unwritten)

		return -EFAULT;

	return 0;

#endif

}



static int
@@ -208,10 +223,12 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj, 
		    struct drm_file *file_priv)

{

	struct drm_i915_gem_object *obj_priv = obj->driver_private;

	drm_i915_private_t *dev_priv = dev->dev_private;

	ssize_t remain;

	loff_t offset;

	loff_t offset, page_base;

	char __user *user_data;

	int ret = 0;

	int page_offset, page_length;

	int ret;



	user_data = (char __user *) (uintptr_t) args->data_ptr;

	remain = args->size;
@@ -235,57 +252,37 @@ i915_gem_gtt_pwrite(struct drm_device *dev, struct drm_gem_object *obj, 
	obj_priv->dirty = 1;



	while (remain > 0) {

		unsigned long pfn;

		int i, o, l;



		/* Operation in this page

		 *

		 * i = page number

		 * o = offset within page

		 * l = bytes to copy

		 * page_base = page offset within aperture

		 * page_offset = offset within page

		 * page_length = bytes to copy for this page

		 */

		i = offset >> PAGE_SHIFT;

		o = offset & (PAGE_SIZE-1);

		l = remain;

		if ((o + l) > PAGE_SIZE)

			l = PAGE_SIZE - o;

		page_base = (offset & ~(PAGE_SIZE-1));

		page_offset = offset & (PAGE_SIZE-1);

		page_length = remain;

		if ((page_offset + remain) > PAGE_SIZE)

			page_length = PAGE_SIZE - page_offset;



		pfn = (dev->agp->base >> PAGE_SHIFT) + i;

		ret = fast_user_write (dev_priv->mm.gtt_mapping, page_base,

				       page_offset, user_data, page_length);



		if (!fast_user_write(pfn, user_data, l, o)) {

			unsigned long unwritten;

			char __iomem *vaddr;



			vaddr = ioremap_wc(pfn << PAGE_SHIFT, PAGE_SIZE);

#if WATCH_PWRITE

			DRM_INFO("pwrite slow i %d o %d l %d "

				 "pfn %ld vaddr %p\n",

				 i, o, l, pfn, vaddr);

#endif

			if (vaddr == NULL) {

				ret = -EFAULT;

				goto fail;

			}

			unwritten = __copy_from_user(vaddr + o, user_data, l);

#if WATCH_PWRITE

			DRM_INFO("unwritten %ld\n", unwritten);

#endif

			iounmap(vaddr);

			if (unwritten) {

				ret = -EFAULT;

		/* If we get a fault while copying data, then (presumably) our

		 * source page isn't available. In this case, use the

		 * non-atomic function

		 */

		if (ret) {

			ret = slow_user_write (dev_priv->mm.gtt_mapping,

					       page_base, page_offset,

					       user_data, page_length);

			if (ret)

				goto fail;

		}

		}



		remain -= l;

		user_data += l;

		offset += l;

		remain -= page_length;

		user_data += page_length;

		offset += page_length;

	}

#if WATCH_PWRITE && 1

	i915_gem_clflush_object(obj);

	i915_gem_dump_object(obj, args->offset + args->size, __func__, ~0);

	i915_gem_clflush_object(obj);

#endif



fail:

	i915_gem_object_unpin(obj);
@@ -1503,12 +1500,12 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj, 
				 struct drm_i915_gem_exec_object *entry)

{

	struct drm_device *dev = obj->dev;

	drm_i915_private_t *dev_priv = dev->dev_private;

	struct drm_i915_gem_relocation_entry reloc;

	struct drm_i915_gem_relocation_entry __user *relocs;

	struct drm_i915_gem_object *obj_priv = obj->driver_private;

	int i, ret;

	uint32_t last_reloc_offset = -1;

	void __iomem *reloc_page = NULL;

	void __iomem *reloc_page;



	/* Choose the GTT offset for our buffer and put it there. */

	ret = i915_gem_object_pin(obj, (uint32_t) entry->alignment);
@@ -1631,24 +1628,9 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj, 
		 * perform.

		 */

		reloc_offset = obj_priv->gtt_offset + reloc.offset;

		if (reloc_page == NULL ||

		    (last_reloc_offset & ~(PAGE_SIZE - 1)) !=

		    (reloc_offset & ~(PAGE_SIZE - 1))) {

			if (reloc_page != NULL)

				iounmap(reloc_page);



			reloc_page = ioremap_wc(dev->agp->base +

		reloc_page = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,

						      (reloc_offset &

						 ~(PAGE_SIZE - 1)),

						PAGE_SIZE);

			last_reloc_offset = reloc_offset;

			if (reloc_page == NULL) {

				drm_gem_object_unreference(target_obj);

				i915_gem_object_unpin(obj);

				return -ENOMEM;

			}

		}



						       ~(PAGE_SIZE - 1)));

		reloc_entry = (uint32_t __iomem *)(reloc_page +

						   (reloc_offset & (PAGE_SIZE - 1)));

		reloc_val = target_obj_priv->gtt_offset + reloc.delta;
@@ -1659,6 +1641,7 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj, 
			  readl(reloc_entry), reloc_val);

#endif

		writel(reloc_val, reloc_entry);

		io_mapping_unmap_atomic(reloc_page);



		/* Write the updated presumed offset for this entry back out

		 * to the user.
@@ -1674,9 +1657,6 @@ i915_gem_object_pin_and_relocate(struct drm_gem_object *obj, 
		drm_gem_object_unreference(target_obj);

	}



	if (reloc_page != NULL)

		iounmap(reloc_page);



#if WATCH_BUF

	if (0)

		i915_gem_dump_object(obj, 128, __func__, ~0);
@@ -2518,6 +2498,10 @@ i915_gem_entervt_ioctl(struct drm_device *dev, void *data, 
	if (ret != 0)

		return ret;



	dev_priv->mm.gtt_mapping = io_mapping_create_wc(dev->agp->base,

							dev->agp->agp_info.aper_size

							* 1024 * 1024);



	mutex_lock(&dev->struct_mutex);

	BUG_ON(!list_empty(&dev_priv->mm.active_list));

	BUG_ON(!list_empty(&dev_priv->mm.flushing_list));
@@ -2535,11 +2519,13 @@ int 
i915_gem_leavevt_ioctl(struct drm_device *dev, void *data,

		       struct drm_file *file_priv)

{

	drm_i915_private_t *dev_priv = dev->dev_private;

	int ret;



	ret = i915_gem_idle(dev);

	drm_irq_uninstall(dev);



	io_mapping_free(dev_priv->mm.gtt_mapping);

	return ret;

}