plan9fox/sys/src/cmd/qi/timing
2011-03-30 19:35:09 +03:00

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units
branch
integer
floating point
on 601
issue at most one per unit per cycle
eight entry instruction queue
can fill queue from cache in one clock cycle
loads from requested address to end of cache block
pipeline
prefetch
includes ins. cache access cycles
decode
execute
writeback
fpu
IQ[3210] → fpu buffer/decode [≥1 cycle] → execute 1 → execute 2 → writeback
iu
IQ0/decode → buffer [if exec busy] → execute [hold for dependency] →
circulate in load/store
writeback
bpu
IQ[3210] → decode/execute → writeback
notes
address calculation must complete before stored value enters write buffer