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BaseMemoryLibSse2: Take advantage of write combining buffers

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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>
This commit is contained in:
Compostella, Jeremy
2020-10-10 04:42:34 +08:00
committed by mergify[bot]
parent 19c87b7d44
commit d25fd8710d
10 changed files with 85 additions and 38 deletions
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11
MdePkg/Library/BaseMemoryLibSse2/Ia32/SetMem.nasm
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@@ -34,7 +34,7 @@ ASM_PFX(InternalMemSetMem):
mov al, [esp + 16] ; al <- Value
xor ecx, ecx
sub ecx, edi
and ecx, 15 ; ecx + edi aligns on 16-byte boundary
and ecx, 63 ; ecx + edi aligns on 16-byte boundary
jz .0
cmp ecx, edx
cmova ecx, edx
@@ -42,8 +42,8 @@ ASM_PFX(InternalMemSetMem):
rep stosb
.0:
mov ecx, edx
and edx, 15
shr ecx, 4 ; ecx <- # of DQwords to set
and edx, 63
shr ecx, 6 ; ecx <- # of DQwords to set
jz @SetBytes
mov ah, al ; ax <- Value | (Value << 8)
add esp, -16
@@ -53,7 +53,10 @@ ASM_PFX(InternalMemSetMem):
movlhps xmm0, xmm0 ; xmm0 <- Value repeats 16 times
.1:
movntdq [edi], xmm0 ; edi should be 16-byte aligned
add edi, 16
movntdq [edi + 16], xmm0
movntdq [edi + 32], xmm0
movntdq [edi + 48], xmm0
add edi, 64
loop .1
mfence
movdqu xmm0, [esp] ; restore xmm0