[Mesa-dev] [PATCH 00/15] GLSL memory allocation rework for faster compilation

[Nicolai Hähnle]

Nice work! I sent some comments on patches 6 & 7. Patches 1-4 and 7-15 are

Reviewed-by: Nicolai Hähnle <nicolai.haehnle at amd.com>

assuming you checked them with a Piglit run in addition to the shader-db.

Something that LLVM does for its intermediate representations is using 
Recycler objects. Instructions are allocated from a linear allocator, 
but when they are removed they are neither returned to the heap nor 
simply forgotten. Instead, the memory block is added to a linked list 
managed by the Recycler object, so that the next instruction allocation 
can be served from there.

I suspect that this could also help here because it's still very fast 
but keeps the cache footprint smaller.

Cheers,
Nicolai

On 08.10.2016 12:58, Marek Olšák wrote:
> Hi,
>
> This patch series reduces the number of malloc calls in the GLSL
> compiler by 63%. That leads to better compile times and less heap
> thrashing.
>
> It's done by switching memory allocations in the GLSL compiler to my
> new linear allocator that allocates out of a fixed-sized buffer with
> a monotonically increasing offset. If more buffers are needed, it
> chains them.
>
> The new allocator is used in all places where short-lived allocations
> are used with a high number of malloc calls. The series also contains
> other improvements not related to the new allocator that also improve
> compile times. The results are below.
>
> I tested my shader-db with shaders only being compiled to TGSI.
> (noop gallium driver)
>
>
> master + libc's malloc:
>
>  real	0m54.182s
>  user	3m33.640s
>  sys	0m0.620s
>  maxmem 275 MB
>
>
> master + jemalloc preloaded:
>
>  real	0m45.044s
>  user	2m56.356s
>  sys	0m1.652s
>  maxmem 284 MB
>
>
> the series + libc's malloc:
>
>  real	0m46.221s
>  user	3m2.080s
>  sys	0m0.544s
>  maxmem 270 MB
>
>
> the series + jemalloc preloaded:
>
>  real	0m40.729s
>  user	2m39.564s
>  sys	0m1.232s
>  maxmem 284 MB
>
>
> The series without jemalloc almost caught up with jemalloc + master.
> However, jemalloc also benefits.
>
> Current Mesa needs 54.182s and it drops to 40.729s with my series and
> jemalloc. The total change in compile time is -25% if we incorporate
> both. Without jemalloc, the difference is only -14.7%.
>
> With radeonsi, the improvement is approx. slightly more than 1/2 of that
> (if you add the LLVM time). However, radeonsi also has asynchronous
> shader compilation hiding LLVM overhead in some cases, so it depends.
>
> Drivers with faster compiler backends will benefit more than radeonsi,
> but will probably not reach -25% or -14.7% (except softpipe, which uses
> TGSI as-is).
>
> The memory usage looks reasonable in all tested cases.
>
> Note: One of the first patches moves memset from ralloc to rzalloc.
> I tested and fixed the GLSL source -> TGSI path, but other codepaths
> may break, and you need to use valgrind to find all uninitialized
> variables that relied on ralloc doing memset (if there are any).
>
> You can also find it here:
> https://cgit.freedesktop.org/~mareko/mesa/log/?h=glsl-alloc-rework
>
> Please review.
>
>  src/compiler/glsl/ast.h                             |   4 +-
>  src/compiler/glsl/ast_to_hir.cpp                    |   4 +-
>  src/compiler/glsl/ast_type.cpp                      |  13 ++-
>  src/compiler/glsl/glcpp/glcpp-lex.l                 |   2 +-
>  src/compiler/glsl/glcpp/glcpp-parse.y               | 203 +++++++++++++++++---------------------
>  src/compiler/glsl/glcpp/glcpp.h                     |   1 +
>  src/compiler/glsl/glsl_lexer.ll                     |  16 +--
>  src/compiler/glsl/glsl_parser.yy                    | 202 +++++++++++++++++++-------------------
>  src/compiler/glsl/glsl_parser_extras.cpp            |   6 +-
>  src/compiler/glsl/glsl_parser_extras.h              |   4 +-
>  src/compiler/glsl/glsl_symbol_table.cpp             |  19 ++--
>  src/compiler/glsl/glsl_symbol_table.h               |   1 +
>  src/compiler/glsl/ir.cpp                            |   4 +
>  src/compiler/glsl/ir.h                              |  13 ++-
>  src/compiler/glsl/link_uniform_blocks.cpp           |   2 +-
>  src/compiler/glsl/list.h                            |   2 +-
>  src/compiler/glsl/lower_packed_varyings.cpp         |   8 +-
>  src/compiler/glsl/opt_constant_propagation.cpp      |  14 ++-
>  src/compiler/glsl/opt_copy_propagation.cpp          |   7 +-
>  src/compiler/glsl/opt_copy_propagation_elements.cpp |  19 ++--
>  src/compiler/glsl/opt_dead_code_local.cpp           |  12 ++-
>  src/compiler/glsl_types.cpp                         |  38 +------
>  src/compiler/glsl_types.h                           |   6 +-
>  src/compiler/nir/nir.c                              |   8 +-
>  src/compiler/spirv/vtn_variables.c                  |   3 +-
>  src/gallium/drivers/freedreno/ir3/ir3.c             |   2 +-
>  src/gallium/drivers/vc4/vc4_cl.c                    |   2 +-
>  src/gallium/drivers/vc4/vc4_program.c               |   2 +-
>  src/gallium/drivers/vc4/vc4_simulator.c             |   5 +-
>  src/mesa/drivers/dri/i965/brw_state_batch.c         |   5 +-
>  src/util/ralloc.c                                   | 392 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++---
>  src/util/ralloc.h                                   |  93 ++++++++++++++++--
>  32 files changed, 782 insertions(+), 330 deletions(-)
>
> Marek
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