RISC-V Design · All levels

Performance Tuning and Signoff: Software and Programmer View

Software and Programmer View for Performance Tuning and Signoff.

Software and programmer view

Software and Programmer View for Performance Tuning and Signoff is anchored on P95 and P99 workload latency, sustained throughput per subsystem, and power-performance target closure against signoff criteria.. Convert observations into mechanism-backed decisions with explicit ownership.

  • Keep ISA profile, ABI, and extension assumptions explicit.

  • Validate runtime feature detection against hardware contract.

  • Correlate compiler output with microarchitectural counters.

  • Preserve deterministic trap and privilege behavior in all modes.

Decode contract

diagram
DECODE CONTROL MAP - Performance Tuning and Signoff

opcode/funct3/funct7      controls asserted
-----------------------   ---------------------------------------
LUI / AUIPC               rd_write, imm_select(U), alu_add_pc
JAL / JALR                rd_write, pc_redirect, link_write
BRANCH                    cmp_enable, branch_type, pc_redirect
LOAD                      mem_read, rd_write, wb_sel(memory)
STORE                     mem_write, store_size, addr_calc
OP-IMM                    alu_enable, imm_select(I), rd_write
OP                        alu_enable, src2_reg, rd_write
SYSTEM / CSR              csr_readwrite, trap_check, privilege_gate
VECTOR (V extension)      vdecode, lane_mask, vtype_update