From: Matteo Croce <[email protected]>
Replace the assembly mem{cpy,move,set} with C equivalent.
Try to access RAM with the largest bit width possible, but without
doing unaligned accesses.
Tested on a BeagleV Starlight with a SiFive U74 core, where the
improvement is noticeable.
v2 -> v3:
- alias mem* to __mem* and not viceversa
- use __alias instead of a tail call
v1 -> v2:
- reduce the threshold from 64 to 16 bytes
- fix KASAN build
- optimize memset
Matteo Croce (3):
riscv: optimized memcpy
riscv: optimized memmove
riscv: optimized memset
arch/riscv/include/asm/string.h | 18 ++--
arch/riscv/kernel/Makefile | 1 -
arch/riscv/kernel/riscv_ksyms.c | 17 ----
arch/riscv/lib/Makefile | 4 +-
arch/riscv/lib/memcpy.S | 108 ----------------------
arch/riscv/lib/memmove.S | 64 -------------
arch/riscv/lib/memset.S | 113 -----------------------
arch/riscv/lib/string.c | 153 ++++++++++++++++++++++++++++++++
8 files changed, 163 insertions(+), 315 deletions(-)
delete mode 100644 arch/riscv/kernel/riscv_ksyms.c
delete mode 100644 arch/riscv/lib/memcpy.S
delete mode 100644 arch/riscv/lib/memmove.S
delete mode 100644 arch/riscv/lib/memset.S
create mode 100644 arch/riscv/lib/string.c
--
2.31.1
Hello Matteo,
Στις 2021-06-17 18:27, Matteo Croce έγραψε:
> From: Matteo Croce <[email protected]>
>
> Replace the assembly mem{cpy,move,set} with C equivalent.
>
> Try to access RAM with the largest bit width possible, but without
> doing unaligned accesses.
>
> Tested on a BeagleV Starlight with a SiFive U74 core, where the
> improvement is noticeable.
>
There are already generic C implementations for memcpy/memmove/memset at
https://elixir.bootlin.com/linux/v5.13-rc7/source/lib/string.c#L871 but
are doing one byte at a time, I suggest you update them to do
word-by-word copy instead of introducing yet another memcpy/memmove C
implementation on arch/riscv/.
On Tue, Jun 22, 2021 at 9:09 AM Nick Kossifidis <[email protected]> wrote:
>
> Hello Matteo,
>
> Στις 2021-06-17 18:27, Matteo Croce έγραψε:
> > From: Matteo Croce <[email protected]>
> >
> > Replace the assembly mem{cpy,move,set} with C equivalent.
> >
> > Try to access RAM with the largest bit width possible, but without
> > doing unaligned accesses.
> >
> > Tested on a BeagleV Starlight with a SiFive U74 core, where the
> > improvement is noticeable.
> >
>
> There are already generic C implementations for memcpy/memmove/memset at
> https://elixir.bootlin.com/linux/v5.13-rc7/source/lib/string.c#L871 but
> are doing one byte at a time, I suggest you update them to do
> word-by-word copy instead of introducing yet another memcpy/memmove C
> implementation on arch/riscv/.
Yes, I've tried to copy the Glibc version into arch/csky/abiv1, and
Arnd suggested putting them into generic.
ref: https://lore.kernel.org/linux-arch/20190629053641.3iBfk9-I_D29cDp9yJnIdIg7oMtHNZlDmhLQPTumhEc@z/#t
>
>
>
--
Best Regards
Guo Ren
ML: https://lore.kernel.org/linux-csky/