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drm/i915: Replace the array of pages with a scatterlist

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Rather than have multiple data structures for describing our page layout
in conjunction with the array of pages, we can migrate all users over to
a scatterlist.

One major advantage, other than unifying the page tracking structures,
this offers is that we replace the vmalloc'ed array (which can be up to
a megabyte in size) with a chain of individual pages which helps reduce
memory pressure.

The disadvantage is that we then do not have a simple array to iterate,
or to access randomly. The common case for this is in the relocation
processing, which will typically fit within a single scatterlist page
and so be almost the same cost as the simple array. For iterating over
the array, the extra function call could be optimised away, but in
reality is an insignificant cost of either binding the pages, or
performing the pwrite/pread.

v2: Fix drm_clflush_sg() to not invoke wbinvd as well! And fix the
trivial compile error from rebasing.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Chris Wilson
2012-06-01 15:20:22 +01:00
committed by Daniel Vetter
parent f60d7f0c1d
commit 9da3da660d
12 changed files with 240 additions and 221 deletions
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25
drivers/gpu/drm/drm_cache.c
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@@ -100,6 +100,31 @@ drm_clflush_pages(struct page *pages[], unsigned long num_pages)
}
EXPORT_SYMBOL(drm_clflush_pages);
void
drm_clflush_sg(struct sg_table *st)
{
#if defined(CONFIG_X86)
if (cpu_has_clflush) {
struct scatterlist *sg;
int i;
mb();
for_each_sg(st->sgl, sg, st->nents, i)
drm_clflush_page(sg_page(sg));
mb();
return;
}
if (on_each_cpu(drm_clflush_ipi_handler, NULL, 1) != 0)
printk(KERN_ERR "Timed out waiting for cache flush.\n");
#else
printk(KERN_ERR "Architecture has no drm_cache.c support\n");
WARN_ON_ONCE(1);
#endif
}
EXPORT_SYMBOL(drm_clflush_sg);
void
drm_clflush_virt_range(char *addr, unsigned long length)
{