IBM z13s, Technical Manual

Page: 121 / 588

Chapter 3. Central processor complex system design
93
Program results
The OoO execution does not change any program results. Execution can occur out of
(program) order, but all program dependencies are honored, ending up with the same results
of the in-order (program) execution.
This implementation requires special circuitry to make execution and memory accesses
display in order to the software. The logical diagram of a z13s core is shown in Figure 3-9.
Figure 3-9 z13 s PU core logical diagram
Memory address generation and memory accesses can occur out of (program) order. This
capability can provide a greater use of the z13s superscalar core, and can improve system
performance.
L2 Dir
VBQ
Decode/Dispatch 1
Clump of instruction (up to 6)
Rename
Group of micro-ops (up to 6)
Issue Queue Issue Queue
Fixed
Pt
Load/
Store 2
Fixed
Pt
Bin/Hex
Floating
Pt
VBU VBU
GPR
FPR
VBQ
InstQ
0cycE
L1 Dir
Group of micro-ops (up to 6)
GCT
Fx Div
Dec Flt
Pt
micro-ops issue (up to 10)
TLB0
TLB
Load/
Store 2
1) on-the-fly OSC detection bubble-free
instruction expansion
2) banking for concurrent load/stores
prefetching enhancements
Out-of-Order (OoO) addition