Mesa (master): util: Add a virtual memory allocator
Jason Ekstrand
jekstrand at kemper.freedesktop.org
Thu May 31 23:54:19 UTC 2018
Module: Mesa
Branch: master
Commit: f19ad5d31fde8c447119c5483b3e3972922e9991
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=f19ad5d31fde8c447119c5483b3e3972922e9991
Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date: Sat Jan 6 17:28:01 2018 -0800
util: Add a virtual memory allocator
This is simple linear-walk first-fit allocator roughly based on the
allocator in the radeon winsys code. This allocator has two primary
functional differences:
1) It cleanly returns 0 on allocation failure
2) It allocates addresses top-down instead of bottom-up.
The second one is needed for Intel because high addresses (with bit 47
set) need to be canonicalized in order to work properly. If we allocate
bottom-up, then high addresses will be very rare (if they ever happen).
We'd rather always have high addresses so that the canonicalization code
gets better testing.
v2: - [scott-ph] remove _heap_validate() if NDEBUG is defined (Jordan)
Reviewed-by: Scott D Phillips <scott.d.phillips at intel.com>
Tested-by: Scott D Phillips <scott.d.phillips at intel.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
src/util/Makefile.sources | 4 +-
src/util/meson.build | 2 +
src/util/vma.c | 234 ++++++++++++++++++++++++++++++++++++++++++++++
src/util/vma.h | 53 +++++++++++
4 files changed, 292 insertions(+), 1 deletion(-)
diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
index 104ecae8ed..534520ce76 100644
--- a/src/util/Makefile.sources
+++ b/src/util/Makefile.sources
@@ -56,7 +56,9 @@ MESA_UTIL_FILES := \
u_string.h \
u_thread.h \
u_vector.c \
- u_vector.h
+ u_vector.h \
+ vma.c \
+ vma.h
MESA_UTIL_GENERATED_FILES = \
format_srgb.c
diff --git a/src/util/meson.build b/src/util/meson.build
index eece1cefef..14660e0fa0 100644
--- a/src/util/meson.build
+++ b/src/util/meson.build
@@ -81,6 +81,8 @@ files_mesa_util = files(
'u_thread.h',
'u_vector.c',
'u_vector.h',
+ 'vma.c',
+ 'vma.h',
)
install_data('drirc', install_dir : get_option('sysconfdir'))
diff --git a/src/util/vma.c b/src/util/vma.c
new file mode 100644
index 0000000000..c8f55031c7
--- /dev/null
+++ b/src/util/vma.c
@@ -0,0 +1,234 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * 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, sublicense,
+ * 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 NONINFRINGEMENT. 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.
+ */
+
+#include <stdlib.h>
+
+#include "util/u_math.h"
+#include "util/vma.h"
+
+struct util_vma_hole {
+ struct list_head link;
+ uint64_t offset;
+ uint64_t size;
+};
+
+#define util_vma_foreach_hole(_hole, _heap) \
+ list_for_each_entry(struct util_vma_hole, _hole, &(_heap)->holes, link)
+
+#define util_vma_foreach_hole_safe(_hole, _heap) \
+ list_for_each_entry_safe(struct util_vma_hole, _hole, &(_heap)->holes, link)
+
+void
+util_vma_heap_init(struct util_vma_heap *heap,
+ uint64_t start, uint64_t size)
+{
+ list_inithead(&heap->holes);
+ util_vma_heap_free(heap, start, size);
+}
+
+void
+util_vma_heap_finish(struct util_vma_heap *heap)
+{
+ util_vma_foreach_hole_safe(hole, heap)
+ free(hole);
+}
+
+#ifndef NDEBUG
+static void
+util_vma_heap_validate(struct util_vma_heap *heap)
+{
+ uint64_t prev_offset = 0;
+ util_vma_foreach_hole(hole, heap) {
+ assert(hole->offset > 0);
+ assert(hole->size > 0);
+
+ if (&hole->link == heap->holes.next) {
+ /* This must be the top-most hole. Assert that, if it overflows, it
+ * overflows to 0, i.e. 2^64.
+ */
+ assert(hole->size + hole->offset == 0 ||
+ hole->size + hole->offset > hole->offset);
+ } else {
+ /* This is not the top-most hole so it must not overflow and, in
+ * fact, must be strictly lower than the top-most hole. If
+ * hole->size + hole->offset == prev_offset, then we failed to join
+ * holes during a util_vma_heap_free.
+ */
+ assert(hole->size + hole->offset > hole->offset &&
+ hole->size + hole->offset < prev_offset);
+ }
+ prev_offset = hole->offset;
+ }
+}
+#else
+#define util_vma_heap_validate(heap)
+#endif
+
+uint64_t
+util_vma_heap_alloc(struct util_vma_heap *heap,
+ uint64_t size, uint64_t alignment)
+{
+ /* The caller is expected to reject zero-size allocations */
+ assert(size > 0);
+ assert(alignment > 0);
+
+ util_vma_heap_validate(heap);
+
+ util_vma_foreach_hole_safe(hole, heap) {
+ if (size > hole->size)
+ continue;
+
+ /* Compute the offset as the highest address where a chunk of the given
+ * size can be without going over the top of the hole.
+ *
+ * This calculation is known to not overflow because we know that
+ * hole->size + hole->offset can only overflow to 0 and size > 0.
+ */
+ uint64_t offset = (hole->size - size) + hole->offset;
+
+ /* Align the offset. We align down and not up because we are allocating
+ * from the top of the hole and not the bottom.
+ */
+ offset = (offset / alignment) * alignment;
+
+ if (offset < hole->offset)
+ continue;
+
+ if (offset == hole->offset && size == hole->size) {
+ /* Just get rid of the hole. */
+ list_del(&hole->link);
+ free(hole);
+ util_vma_heap_validate(heap);
+ return offset;
+ }
+
+ assert(offset - hole->offset <= hole->size - size);
+ uint64_t waste = (hole->size - size) - (offset - hole->offset);
+ if (waste == 0) {
+ /* We allocated at the top. Shrink the hole down. */
+ hole->size -= size;
+ util_vma_heap_validate(heap);
+ return offset;
+ }
+
+ if (offset == hole->offset) {
+ /* We allocated at the bottom. Shrink the hole up. */
+ hole->offset += size;
+ hole->size -= size;
+ util_vma_heap_validate(heap);
+ return offset;
+ }
+
+ /* We allocated in the middle. We need to split the old hole into two
+ * holes, one high and one low.
+ */
+ struct util_vma_hole *high_hole = calloc(1, sizeof(*hole));
+ high_hole->offset = offset + size;
+ high_hole->size = waste;
+
+ /* Adjust the hole to be the amount of space left at he bottom of the
+ * original hole.
+ */
+ hole->size = offset - hole->offset;
+
+ /* Place the new hole before the old hole so that the list is in order
+ * from high to low.
+ */
+ list_addtail(&high_hole->link, &hole->link);
+
+ util_vma_heap_validate(heap);
+
+ return offset;
+ }
+
+ /* Failed to allocate */
+ return 0;
+}
+
+void
+util_vma_heap_free(struct util_vma_heap *heap,
+ uint64_t offset, uint64_t size)
+{
+ /* An offset of 0 is reserved for allocation failure. It is not a valid
+ * address and cannot be freed.
+ */
+ assert(offset > 0);
+
+ /* Freeing something with a size of 0 is also not valid. */
+ assert(size > 0);
+
+ /* It's possible for offset + size to wrap around if we touch the top of
+ * the 64-bit address space, but we cannot go any higher than 2^64.
+ */
+ assert(offset + size == 0 || offset + size > offset);
+
+ util_vma_heap_validate(heap);
+
+ /* Find immediately higher and lower holes if they exist. */
+ struct util_vma_hole *high_hole = NULL, *low_hole = NULL;
+ util_vma_foreach_hole(hole, heap) {
+ if (hole->offset <= offset) {
+ low_hole = hole;
+ break;
+ }
+ high_hole = hole;
+ }
+
+ if (high_hole)
+ assert(offset + size <= high_hole->offset);
+ bool high_adjacent = high_hole && offset + size == high_hole->offset;
+
+ if (low_hole) {
+ assert(low_hole->offset + low_hole->size > low_hole->offset);
+ assert(low_hole->offset + low_hole->size <= offset);
+ }
+ bool low_adjacent = low_hole && low_hole->offset + low_hole->size == offset;
+
+ if (low_adjacent && high_adjacent) {
+ /* Merge the two holes */
+ low_hole->size += size + high_hole->size;
+ list_del(&high_hole->link);
+ free(high_hole);
+ } else if (low_adjacent) {
+ /* Merge into the low hole */
+ low_hole->size += size;
+ } else if (high_adjacent) {
+ /* Merge into the high hole */
+ high_hole->offset = offset;
+ high_hole->size += size;
+ } else {
+ /* Neither hole is adjacent; make a new one */
+ struct util_vma_hole *hole = calloc(1, sizeof(*hole));
+
+ hole->offset = offset;
+ hole->size = size;
+
+ /* Add it after the high hole so we maintain high-to-low ordering */
+ if (high_hole)
+ list_add(&hole->link, &high_hole->link);
+ else
+ list_add(&hole->link, &heap->holes);
+ }
+
+ util_vma_heap_validate(heap);
+}
diff --git a/src/util/vma.h b/src/util/vma.h
new file mode 100644
index 0000000000..ed69914e4c
--- /dev/null
+++ b/src/util/vma.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright © 2018 Intel Corporation
+ *
+ * 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, sublicense,
+ * 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 NONINFRINGEMENT. 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.
+ */
+
+#ifndef _UTIL_VMA_H
+#define _UTIL_VMA_H
+
+#include <stdint.h>
+
+#include "list.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct util_vma_heap {
+ struct list_head holes;
+};
+
+void util_vma_heap_init(struct util_vma_heap *heap,
+ uint64_t start, uint64_t size);
+void util_vma_heap_finish(struct util_vma_heap *heap);
+
+uint64_t util_vma_heap_alloc(struct util_vma_heap *heap,
+ uint64_t size, uint64_t alignment);
+
+void util_vma_heap_free(struct util_vma_heap *heap,
+ uint64_t offset, uint64_t size);
+
+#ifdef __cplusplus
+} /* extern C */
+#endif
+
+#endif /* _UTIL_DEBUG_H */
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