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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: Keith Packard <keithp@keithp.com>
Signed-off-by: Eric Anholt <eric@anholt.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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1 parent 9663f2e commit 0839ccb8ac6a9e2d5e175a4ae9c82b5c574d510d @keith-packard keith-packard committed with Ingo Molnar Oct 31, 2008
Showing with 83 additions and 94 deletions.
  1. +3 −0 drivers/gpu/drm/i915/i915_drv.h
  2. +80 −94 drivers/gpu/drm/i915/i915_gem.c
@@ -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.
@@ -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;
-
- pfn = (dev->agp->base >> PAGE_SHIFT) + i;
-
- 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;
+ 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;
+
+ ret = fast_user_write (dev_priv->mm.gtt_mapping, page_base,
+ page_offset, user_data, page_length);
+
+ /* 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);
@@ -1631,26 +1628,11 @@ 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_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;
- }
- }
-
+ reloc_page = io_mapping_map_atomic_wc(dev_priv->mm.gtt_mapping,
+ (reloc_offset &
+ ~(PAGE_SIZE - 1)));
reloc_entry = (uint32_t __iomem *)(reloc_page +
- (reloc_offset & (PAGE_SIZE - 1)));
+ (reloc_offset & (PAGE_SIZE - 1)));
reloc_val = target_obj_priv->gtt_offset + reloc.delta;
#if WATCH_BUF
@@ -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;
}

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