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RandomX: added parameter for scratchpad prefetch mode

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`scratchpad_prefetch_mode` can have 4 values:
0: off
1: use `prefetcht0` instruction (default, same as previous XMRig versions)
2: use `prefetchnta` instruction (faster on Coffee Lake and a few other CPUs)
3: use `mov` instruction
This commit is contained in:
SChernykh 2020-09-04 16:16:07 +02:00
parent a5b6383f7b
commit a84b45b1bb
7 changed files with 71 additions and 2 deletions
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37
src/crypto/randomx/randomx.cpp
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@ -211,6 +211,13 @@ RandomX_ConfigurationBase::RandomX_ConfigurationBase()
static uint32_t Log2(size_t value) { return (value > 1) ? (Log2(value / 2) + 1) : 0; }
#endif
static int scratchpadPrefetchMode = 1;
void randomx_set_scratchpad_prefetch_mode(int mode)
{
scratchpadPrefetchMode = mode;
}
void RandomX_ConfigurationBase::Apply()
{
const uint32_t ScratchpadL1Mask_Calculated = (ScratchpadL1_Size / sizeof(uint64_t) - 1) * 8;
@ -240,6 +247,36 @@ void RandomX_ConfigurationBase::Apply()
*(uint32_t*)(codePrefetchScratchpadTweaked + 4) = ScratchpadL3Mask64_Calculated;
*(uint32_t*)(codePrefetchScratchpadTweaked + 18) = ScratchpadL3Mask64_Calculated;
// Apply scratchpad prefetch mode
{
uint32_t* a = (uint32_t*)(codePrefetchScratchpadTweaked + 8);
uint32_t* b = (uint32_t*)(codePrefetchScratchpadTweaked + 22);
switch (scratchpadPrefetchMode)
{
case 0:
*a = 0x00401F0FUL; // 4-byte nop
*b = 0x00401F0FUL; // 4-byte nop
break;
case 1:
default:
*a = 0x060C180FUL; // prefetcht0 [rsi+rax]
*b = 0x160C180FUL; // prefetcht0 [rsi+rdx]
break;
case 2:
*a = 0x0604180FUL; // prefetchnta [rsi+rax]
*b = 0x1604180FUL; // prefetchnta [rsi+rdx]
break;
case 3:
*a = 0x060C8B48UL; // mov rcx, [rsi+rax]
*b = 0x160C8B48UL; // mov rcx, [rsi+rdx]
break;
}
}
#define JIT_HANDLE(x, prev) randomx::JitCompilerX86::engine[k] = &randomx::JitCompilerX86::h_##x
#elif defined(XMRIG_ARMv8)