I compiled a libsvm benchmarking app which does svm_predict() 100 times on the same image using the same model. The libsvm is compiled statically (MSVC 2017) by directly including svm.cpp and svm.h in my project.
EDIT: adding benchmark details
for (int i = 0; i < counter; i++)
{
std::chrono::high_resolution_clock::time_point t1 = std::chrono::high_resolution_clock::now();
double label = svm_predict(model, input);
std::chrono::high_resolution_clock::time_point t2 = std::chrono::high_resolution_clock::now();
auto duration = std::chrono::duration_cast<std::chrono::microseconds>(t2 - t1).count();
total_time += duration;
std::cout << "\n\n\n" << sum << " label:" << label << " duration:" << duration << "\n\n\n";
}
This is the loop that I benchmark without any major modifications to the libsvm code.
After 100 runs the average of one run is 4.7 ms with no difference if I use or not AVX instructions. To make sure the compiler generates the correct instructions I used Intel Software Development Emulator to check the instructions mix
with AVX:
*isa-ext-AVX 36578280
*isa-ext-SSE 4
*isa-ext-SSE2 4
*isa-set-SSE 4
*isa-set-SSE2 4
*scalar-simd 36568174
*sse-scalar 4
*sse-packed 4
*avx-scalar 36568170
*avx128 8363
*avx256 1765
The other part
without AVX:
*isa-ext-SSE 11781
*isa-ext-SSE2 36574119
*isa-set-SSE 11781
*isa-set-SSE2 36574119
*scalar-simd 36564559
*sse-scalar 36564559
*sse-packed 21341
I would expect to get some performance improvment I know that avx128/256/512 are not used that much but still. I have a i7-8550U CPU, do you think that if run the same test on a skylake i9 X series I would see a bigger difference ?
EDIT I added the instruction mix for each binary
With AVX:
ADD 16868725
AND 49
BT 6
CALL_NEAR 14032515
CDQ 4
CDQE 3601
CMOVLE 6
CMOVNZ 2
CMOVO 12
CMOVZ 6
CMP 25417120
CMPXCHG_LOCK 1
CPUID 3
CQO 12
DEC 68
DIV 1
IDIV 12
IMUL 3621
INC 8496372
JB 325
JBE 5
JL 7101
JLE 38338
JMP 8416984
JNB 6
JNBE 3
JNL 806
JNLE 61
JNS 1
JNZ 22568320
JS 2
JZ 8465164
LEA 16829868
MOV 42209230
MOVSD_XMM 4
MOVSXD 1141
MOVUPS 4
MOVZX 3684
MUL 12
NEG 72
NOP 4219
NOT 1
OR 14
POP 1869
PUSH 1870
REP_STOSD 6
RET_NEAR 1758
ROL 5
ROR 10
SAR 8
SBB 5
SETNZ 4
SETZ 26
SHL 1626
SHR 519
SUB 6530
TEST 5616533
VADDPD 594
VADDSD 8445597
VCOMISD 3
VCVTSI2SD 3603
VEXTRACTF128 6
VFMADD132SD 12
VFMADD231SD 6
VHADDPD 6
VMOVAPD 12
VMOVAPS 2375
VMOVDQU 1
VMOVSD 11256384
VMOVUPD 582
VMULPD 582
VMULSD 8451540
VPXOR 1
VSUBSD 8407425
VUCOMISD 3600
VXORPD 2362
VXORPS 3603
VZEROUPPER 4
XCHG 8
XGETBV 1
XOR 8414763
*total 213991340
Part2
No AVX:
ADD 16869910
ADDPD 1176
ADDSD 8445609
AND 49
BT 6
CALL_NEAR 14032515
CDQ 4
CDQE 3601
CMOVLE 6
CMOVNZ 2
CMOVO 12
CMOVZ 6
CMP 25417408
CMPXCHG_LOCK 1
COMISD 3
CPUID 3
CQO 12
CVTDQ2PD 3603
DEC 68
DIV 1
IDIV 12
IMUL 3621
INC 8496369
JB 325
JBE 5
JL 7392
JLE 38338
JMP 8416984
JNB 6
JNBE 3
JNL 803
JNLE 61
JNS 1
JNZ 22568317
JS 2
JZ 8465164
LEA 16829548
MOV 42209235
MOVAPS 7073
MOVD 3603
MOVDQU 2
MOVSD_XMM 11256376
MOVSXD 1141
MOVUPS 2344
MOVZX 3684
MUL 12
MULPD 1170
MULSD 8451546
NEG 72
NOP 4159
NOT 1
OR 14
POP 1865
PUSH 1866
REP_STOSD 6
RET_NEAR 1758
ROL 5
ROR 10
SAR 8
SBB 5
SETNZ 4
SETZ 26
SHL 1626
SHR 516
SUB 6515
SUBSD 8407425
TEST 5616533
UCOMISD 3600
UNPCKHPD 6
XCHG 8
XGETBV 1
XOR 8414745
XORPS 2364
*total 214000270
