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system76-edk2/MdePkg/Library/BaseMemoryLibSse2/X64/SetMem16.nasm
Compostella, Jeremy d25fd8710d BaseMemoryLibSse2: Take advantage of write combining buffers
The current SSE2 implementation of the ZeroMem(), SetMem(),
SetMem16(), SetMem32 and SetMem64 functions is writing 16 bytes per 16
bytes. It hurts the performances so bad that this is even slower than
a simple 'rep stos' (4% slower) in regular DRAM.

To take full advantages of the 'movntdq' instruction it is better to
"queue" a total of 64 bytes in the write combining buffers.  This
patch implement such a change.  Below is a table where I measured
(with 'rdtsc') the time to write an entire 100MB RAM buffer. These
functions operate almost two times faster.

| Function | Arch | Untouched | 64 bytes | Result |
|----------+------+-----------+----------+--------|
| ZeroMem  | Ia32 |  17765947 |  9136062 | 1.945x |
| ZeroMem  | X64  |  17525170 |  9233391 | 1.898x |
| SetMem   | Ia32 |  17522291 |  9137272 | 1.918x |
| SetMem   | X64  |  17949261 |  9176978 | 1.956x |
| SetMem16 | Ia32 |  18219673 |  9372062 | 1.944x |
| SetMem16 | X64  |  17523331 |  9275184 | 1.889x |
| SetMem32 | Ia32 |  18495036 |  9273053 | 1.994x |
| SetMem32 | X64  |  17368864 |  9285885 | 1.870x |
| SetMem64 | Ia32 |  18564473 |  9241362 | 2.009x |
| SetMem64 | X64  |  17506951 |  9280148 | 1.886x |

Signed-off-by: Jeremy Compostella <jeremy.compostella@intel.com>
Reviewed-by: Liming Gao <gaoliming@byosoft.com.cn>
2020-10-16 01:12:05 +00:00

67 lines
1.4 KiB
NASM

;------------------------------------------------------------------------------
;
; Copyright (c) 2006, Intel Corporation. All rights reserved.<BR>
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
; Module Name:
;
; SetMem16.nasm
;
; Abstract:
;
; SetMem16 function
;
; Notes:
;
;------------------------------------------------------------------------------
DEFAULT REL
SECTION .text
;------------------------------------------------------------------------------
; VOID *
; InternalMemSetMem16 (
; IN VOID *Buffer,
; IN UINTN Count,
; IN UINT16 Value
; )
;------------------------------------------------------------------------------
global ASM_PFX(InternalMemSetMem16)
ASM_PFX(InternalMemSetMem16):
push rdi
mov rdi, rcx
mov r9, rdi
xor rcx, rcx
sub rcx, rdi
and rcx, 63
mov rax, r8
jz .0
shr rcx, 1
cmp rcx, rdx
cmova rcx, rdx
sub rdx, rcx
rep stosw
.0:
mov rcx, rdx
and edx, 31
shr rcx, 5
jz @SetWords
movd xmm0, eax
pshuflw xmm0, xmm0, 0
movlhps xmm0, xmm0
.1:
movntdq [rdi], xmm0
movntdq [rdi + 16], xmm0
movntdq [rdi + 32], xmm0
movntdq [rdi + 48], xmm0
add rdi, 64
loop .1
mfence
@SetWords:
mov ecx, edx
rep stosw
mov rax, r9
pop rdi
ret