drm/ttm: add pool wc/uc page allocator V3

On AGP system we might allocate/free routinely uncached or wc memory,
changing page from cached (wb) to uc or wc is very expensive and involves
a lot of flushing. To improve performance this allocator use a pool
of uc,wc pages.

Pools are protected with spinlocks to allow multiple threads to allocate pages
simultanously. Expensive operations are done outside of spinlock to maximize
concurrency.

Pools are linked lists of pages that were recently freed. mm shrink callback
allows kernel to claim back pages when they are required for something else.

Fixes:
* set_pages_array_wb handles highmem pages so we don't have to remove them
  from pool.
* Add count parameter to ttm_put_pages to avoid looping in free code.
* Change looping from _safe to normal in pool fill error path.
* Initialize sum variable and make the loop prettier in get_num_unused_pages.

* Moved pages_freed reseting inside the loop in ttm_page_pool_free.
* Add warning comment about spinlock context in ttm_page_pool_free.

Based on Jerome Glisse's and Dave Airlie's pool allocator.

Signed-off-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Signed-off-by: Pauli Nieminen <suokkos@gmail.com>
Reviewed-by: Jerome Glisse <jglisse@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/include/drm/ttm/ttm_page_alloc.h b/include/drm/ttm/ttm_page_alloc.h
new file mode 100644
index 0000000..043d817
--- /dev/null
+++ b/include/drm/ttm/ttm_page_alloc.h
@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) Red Hat Inc.
+
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sub license,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ *
+ * Authors: Dave Airlie <airlied@redhat.com>
+ *          Jerome Glisse <jglisse@redhat.com>
+ */
+#ifndef TTM_PAGE_ALLOC
+#define TTM_PAGE_ALLOC
+
+#include "ttm_bo_driver.h"
+#include "ttm_memory.h"
+
+/**
+ * Get count number of pages from pool to pages list.
+ *
+ * @pages: heado of empty linked list where pages are filled.
+ * @flags: ttm flags for page allocation.
+ * @cstate: ttm caching state for the page.
+ * @count: number of pages to allocate.
+ */
+int ttm_get_pages(struct list_head *pages,
+		  int flags,
+		  enum ttm_caching_state cstate,
+		  unsigned count);
+/**
+ * Put linked list of pages to pool.
+ *
+ * @pages: list of pages to free.
+ * @page_count: number of pages in the list. Zero can be passed for unknown
+ * count.
+ * @flags: ttm flags for page allocation.
+ * @cstate: ttm caching state.
+ */
+void ttm_put_pages(struct list_head *pages,
+		   unsigned page_count,
+		   int flags,
+		   enum ttm_caching_state cstate);
+/**
+ * Initialize pool allocator.
+ *
+ * Pool allocator is internaly reference counted so it can be initialized
+ * multiple times but ttm_page_alloc_fini has to be called same number of
+ * times.
+ */
+int ttm_page_alloc_init(unsigned max_pages);
+/**
+ * Free pool allocator.
+ */
+void ttm_page_alloc_fini(void);
+
+#endif