[Mesa-dev] [PATCH 7/8] gallium/util: add a linear allocator for reducing malloc overhead
Marek Olšák
maraeo at gmail.com
Sat Jan 19 01:10:11 UTC 2019
On Fri, Jan 18, 2019 at 6:08 PM Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
wrote:
> On Fri, Jan 18, 2019 at 5:44 PM Marek Olšák <maraeo at gmail.com> wrote:
> >
> > From: Marek Olšák <marek.olsak at amd.com>
> >
> > ---
> > src/gallium/auxiliary/Makefile.sources | 1 +
> > src/gallium/auxiliary/meson.build | 1 +
> > src/gallium/auxiliary/util/u_cpu_suballoc.h | 90 +++++++++++++++++++++
> > 3 files changed, 92 insertions(+)
> > create mode 100644 src/gallium/auxiliary/util/u_cpu_suballoc.h
> >
> > diff --git a/src/gallium/auxiliary/Makefile.sources
> b/src/gallium/auxiliary/Makefile.sources
> > index 50e88088ff8..b26415858f6 100644
> > --- a/src/gallium/auxiliary/Makefile.sources
> > +++ b/src/gallium/auxiliary/Makefile.sources
> > @@ -211,20 +211,21 @@ C_SOURCES := \
> > util/u_bitmask.c \
> > util/u_bitmask.h \
> > util/u_blend.h \
> > util/u_blit.c \
> > util/u_blit.h \
> > util/u_blitter.c \
> > util/u_blitter.h \
> > util/u_box.h \
> > util/u_cache.c \
> > util/u_cache.h \
> > + util/u_cpu_suballoc.h \
> > util/u_debug_gallium.h \
> > util/u_debug_gallium.c \
> > util/u_debug_describe.c \
> > util/u_debug_describe.h \
> > util/u_debug_flush.c \
> > util/u_debug_flush.h \
> > util/u_debug_image.c \
> > util/u_debug_image.h \
> > util/u_debug_memory.c \
> > util/u_debug_refcnt.c \
> > diff --git a/src/gallium/auxiliary/meson.build
> b/src/gallium/auxiliary/meson.build
> > index 57f7e69050f..7e1e4732421 100644
> > --- a/src/gallium/auxiliary/meson.build
> > +++ b/src/gallium/auxiliary/meson.build
> > @@ -231,20 +231,21 @@ files_libgallium = files(
> > 'util/u_bitmask.c',
> > 'util/u_bitmask.h',
> > 'util/u_blend.h',
> > 'util/u_blit.c',
> > 'util/u_blit.h',
> > 'util/u_blitter.c',
> > 'util/u_blitter.h',
> > 'util/u_box.h',
> > 'util/u_cache.c',
> > 'util/u_cache.h',
> > + 'util/u_cpu_suballoc.h',
> > 'util/u_debug_gallium.h',
> > 'util/u_debug_gallium.c',
> > 'util/u_debug_describe.c',
> > 'util/u_debug_describe.h',
> > 'util/u_debug_flush.c',
> > 'util/u_debug_flush.h',
> > 'util/u_debug_image.c',
> > 'util/u_debug_image.h',
> > 'util/u_debug_memory.c',
> > 'util/u_debug_refcnt.c',
> > diff --git a/src/gallium/auxiliary/util/u_cpu_suballoc.h
> b/src/gallium/auxiliary/util/u_cpu_suballoc.h
> > new file mode 100644
> > index 00000000000..2373c1f7c70
> > --- /dev/null
> > +++ b/src/gallium/auxiliary/util/u_cpu_suballoc.h
> > @@ -0,0 +1,90 @@
> >
> +/**************************************************************************
> > + *
> > + * Copyright 2019 Advanced Micro Devices, Inc.
> > + * All Rights Reserved.
> > + *
> > + * 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 AUTHORS AND/OR ITS SUPPLIERS 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.
> > + *
> > +
> **************************************************************************/
> > +
> > +/* A simple utility for suballocating out of malloc_aligned. */
> > +
> > +#ifndef U_CPU_SUBALLOC_H
> > +#define U_CPU_SUBALLOC_H
> > +
> > +#include <stdint.h>
> > +#include "util/os_memory.h"
> > +
> > +struct u_cpu_suballoc {
> > + unsigned default_size; /* Default size of the buffer, in bytes. */
> > + unsigned current_size; /* Current size of the buffer, in bytes. */
> > + unsigned alignment; /* malloc alignment. */
> > + unsigned offset; /* Offset pointing to the first unused byte.
> */
> > + uint8_t *buffer; /* Pointer to the CPU buffer. */
> > +};
> > +
> > +
> > +static inline void
> > +u_cpu_suballoc_init(struct u_cpu_suballoc *alloc, unsigned default_size,
> > + unsigned alignment)
> > +{
> > + memset(alloc, 0, sizeof(*alloc));
> > + alloc->default_size = default_size;
> > + alloc->alignment = alignment;
> > +}
> > +
> > +
> > +static inline void
> > +u_cpu_suballoc_deinit(struct u_cpu_suballoc *alloc)
> > +{
> > + os_free_aligned(alloc->buffer);
> > + alloc->buffer = NULL;
> > +}
> > +
> > +
> > +static inline void *
> > +u_cpu_suballoc(struct u_cpu_suballoc *alloc, unsigned size, unsigned
> alignment)
> > +{
> > + unsigned offset = align(alloc->offset, alignment);
> > +
> > + /* Make sure we have enough space in the buffer for the
> sub-allocation. */
> > + if (unlikely(!alloc->buffer || offset + size > alloc->current_size))
> {
> > + os_free_aligned(alloc->buffer);
>
> So, if we can free the memory during a suballocation, how do we make
> sure that the previous allocations are valid? If they don't have to
> stay valid, why use a linear allocator at all?
>
The assumption is that previously allocated memory won't be accessed after
the next call to u_cpu_suballoc. Yeah it's pretty fragile.
Marek
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