Hi!
Jiong says:
Currently, compiler will lower memcpy function call in XDP/eBPF C program
into a sequence of eBPF load/store pairs for some scenarios.
Compiler is thinking this "inline" optimiation is beneficial as it could
avoid function call and also increase code locality.
However, Netronome NPU is not an tranditional load/store architecture that
doing a sequence of individual load/store actions are not efficient.
This patch set tries to identify the load/store sequences composed of
load/store pairs that comes from memcpy lowering, then accelerates them
through NPU's Command Push Pull (CPP) instruction.
This patch set registered an new optimization pass before doing the actual
JIT work, it traverse through eBPF IR, once found candidate sequence then
record the memory copy source, destination and length information in the
first load instruction starting the sequence and marks all remaining
instructions in the sequence into skipable status. Later, when JITing the
first load instructoin, optimal instructions will be generated using those
record information.
For this safety of this transformation:
- jump into the middle of the sequence will cancel the optimization.
- overlapped memory access will cancel the optimization.
- the load destination register still contains the same value as before
the transformation.
Jakub Kicinski (2):
nfp: fix old kdoc issues
nfp: bpf: encode indirect commands
Jiong Wang (11):
nfp: bpf: support backward jump
nfp: bpf: record jump destination to simplify jump fixup
nfp: bpf: flag jump destination to guide insn combine optimizations
nfp: bpf: don't do ld/mask combination if mask is jump destination
nfp: bpf: don't do ld/shifts combination if shifts are jump
destination
nfp: bpf: relax source operands check
nfp: bpf: correct the encoding for No-Dest immed
nfp: bpf: factor out is_mbpf_load & is_mbpf_store
nfp: bpf: implement memory bulk copy for length within 32-bytes
nfp: bpf: implement memory bulk copy for length bigger than 32-bytes
nfp: bpf: detect load/store sequences lowered from memory copy
drivers/net/ethernet/netronome/nfp/bpf/jit.c | 489 ++++++++++++++++++---
drivers/net/ethernet/netronome/nfp/bpf/main.h | 35 +-
drivers/net/ethernet/netronome/nfp/bpf/offload.c | 23 +-
drivers/net/ethernet/netronome/nfp/bpf/verifier.c | 8 +-
drivers/net/ethernet/netronome/nfp/nfp_asm.c | 7 +-
drivers/net/ethernet/netronome/nfp/nfp_asm.h | 7 +-
drivers/net/ethernet/netronome/nfp/nfp_net.h | 2 +
.../ethernet/netronome/nfp/nfpcore/nfp_cppcore.c | 9 +-
8 files changed, 505 insertions(+), 75 deletions(-)
--
2.15.0
