openhwgroup
PMP is too slow
PMP is on the critical path, and only got worse after checking that the upper end of the access does not go beyond the top of the region. It would be great to speed up PMP. Perhaps some precomputations are possible.
One solution would be to cache the PMP permissions for a page in the TLB entry. If virtual memory is on and the TLB hits, PMP checking is fast. Otherwise, add another cycle to do PMP checking. If the page does not match a single PMP region, don't cache the PMP for that page, and check on the extra cycle.
Is this enhancement causing my build problem today?
(cvw) piet@piet-Precision-7780:/src/piet/cvw/cvw$ make all make -C tests/riscof mkdir -p riscof_work mkdir -p work/riscv-arch-test sed 's,{0},/src/piet/cvw/cvw.lattest/tests/riscof,g;s,{1},32e,g;s,{2},27,g' config.ini > config32e.ini riscof run --work-dir=./riscof_work/arch32e --config=config32e.ini --suite=/src/piet/cvw/cvw/addins/riscv-arch-test/riscv-test-suite/ --env=/src/piet/cvw/cvw/addins/riscv-arch-test/riscv-test-suite/env --no-browser INFO | ****** RISCOF: RISC-V Architectural Test Framework 1.25.3 ******* INFO | using riscv_isac version : 0.18.0 INFO | using riscv_config version : 3.18.3 INFO | Reading configuration from: /src/piet/cvw/cvw.lattest/tests/riscof/config32e.ini INFO | Preparing Models INFO | Input-ISA file INFO | ISACheck: Loading input file: /src/piet/cvw/cvw.lattest/tests/riscof/spike/spike_rv32e_isa.yaml INFO | ISACheck: Load Schema /opt/riscv/riscv-python/lib/python3.12/site-packages/riscv_config/schemas/schema_isa.yaml INFO | ISACheck: Processing Hart:0 INFO | ISACheck: Initiating Validation for Hart:0 ERROR | ISACheck: Error in /src/piet/cvw/cvw.lattest/tests/riscof/spike/spike_rv32e_isa.yaml. ERROR | PMP: ERROR | - unknown field make[1]: *** [Makefile:30: arch32e] Error 1 rm config32e.ini make: *** [Makefile:15: riscof] Error 2 (cvw) piet@piet-Precision-7780:/src/piet/cvw/cvw$
