[Mesa-dev] [PATCH 1/9] util: Add a virtual memory allocator
Jason Ekstrand
jason at jlekstrand.net
Wed May 2 18:36:08 UTC 2018
Marek & Nicolai,
FYI, I am NOT trying to NIH anything here. My hope was that eventually,
the radeon winsys code and the Intel drivers should share an allocator. I
considered starting by pulling the one out of the radeon winsys code and
modifying it but there were a couple of issues (mentioned below) and I
didn't want to start stuff off by changing the behavior of your driver.
:-) Please review and give your opinions as to whether or not the version
here would work for radeon's use-cases.
--Jason
On Wed, May 2, 2018 at 9:01 AM, Scott D Phillips <scott.d.phillips at intel.com
> wrote:
> From: Jason Ekstrand <jason.ekstrand at intel.com>
>
> 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.
> ---
> src/util/Makefile.sources | 4 +-
> src/util/meson.build | 2 +
> src/util/vma.c | 231 ++++++++++++++++++++++++++++++
> ++++++++++++++++
> src/util/vma.h | 53 +++++++++++
> 4 files changed, 289 insertions(+), 1 deletion(-)
> create mode 100644 src/util/vma.c
> create mode 100644 src/util/vma.h
>
> diff --git a/src/util/Makefile.sources b/src/util/Makefile.sources
> index 104ecae8ed3..534520ce763 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 eece1cefef6..14660e0fa0c 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 00000000000..0d4e097e21f
> --- /dev/null
> +++ b/src/util/vma.c
> @@ -0,0 +1,231 @@
> +/*
> + * 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);
> +}
> +
> +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;
> + }
> +}
> +
> +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(util_is_power_of_two_nonzero(alignment));
> +
> + 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 &= ~(alignment - 1);
> +
> + 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 00000000000..ed69914e4cb
> --- /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 */
> --
> 2.14.3
>
>
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