mlp.md

MLP vs size for SKL, SKX and Zen2. Insprired by similar charts produced by Andrei at AnandTech.

Size here is in 8-byte units (sorry), so 10^7 means 80,000,000 bytes.

Data is generated using the console version of MemoryLanes:

MLP_CSV=2 MLP_START=1 MLP_STOP=20000 ./testingmlp > out

Charts generated like:

./plot-csv.py --no-legend --xscale log --ylabel Speedup --title "Zen2 MLP (no THP)" out

Skylake-S (i7-6700HQ)

4k pages:

2MB pages:

Skylake-X (W-2104)

4k pages:

2MB pages:

Zen2 (EPYC 7262)

4k pages:

2MB pages:

Disas

Disassembly of core loop for the 10-chain method naked_access_10:

3c0:
add    rcx,0x1
mov    r14,QWORD PTR [rsi+r14*8]
mov    r13,QWORD PTR [rsi+r13*8]
cmp    rdx,rcx
mov    r12,QWORD PTR [rsi+r12*8]
mov    rbp,QWORD PTR [rsi+rbp*8]
mov    rbx,QWORD PTR [rsi+rbx*8]
mov    r11,QWORD PTR [rsi+r11*8]
mov    r10,QWORD PTR [rsi+r10*8]
mov    r9,QWORD PTR [rsi+r9*8]
mov    r8,QWORD PTR [rsi+r8*8]
mov    rdi,QWORD PTR [rsi+rdi*8]
jne    3c0 <naked_access_10(unsigned long const*, u