From: Alexei Starovoitov <a...@fb.com> Date: Wed, 15 Mar 2017 18:26:38 -0700
> bpf_map_lookup_elem() is one of the most frequently used helper functions. > Improve JITed program performance by inlining this helper. > > bpf_map_type before after > hash 58M 74M > array 174M 280M > > The values are number of lookups per second in ideal conditions > measured by micro-benchmark in patch 6. > > The 'perf report' for HASH map type: > before: > 54.23% map_perf_test [kernel.kallsyms] [k] __htab_map_lookup_elem > 14.24% map_perf_test [kernel.kallsyms] [k] lookup_elem_raw > 8.84% map_perf_test [kernel.kallsyms] [k] htab_map_lookup_elem > 5.93% map_perf_test [kernel.kallsyms] [k] bpf_map_lookup_elem > 2.30% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2 > 1.49% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler > > after: > 60.03% map_perf_test [kernel.kallsyms] [k] __htab_map_lookup_elem > 18.07% map_perf_test [kernel.kallsyms] [k] lookup_elem_raw > 2.91% map_perf_test [kernel.kallsyms] [k] bpf_prog_da4fc6a3f41761a2 > 1.94% map_perf_test [kernel.kallsyms] [k] _einittext > 1.90% map_perf_test [kernel.kallsyms] [k] __audit_syscall_exit > 1.72% map_perf_test [kernel.kallsyms] [k] kprobe_ftrace_handler > > so the cost of htab_map_lookup_elem() and bpf_map_lookup_elem() > is gone after inlining. > > 'per-cpu' and 'lru' map types can be optimized similarly in the future. > > Note the sparse will complain that bpf is addictive ;) > kernel/bpf/hashtab.c:438:19: sparse: subtraction of functions? Share your > drugs > kernel/bpf/verifier.c:3342:38: sparse: subtraction of functions? Share your > drugs > it's not a new warning, just in new places. Series applied, thanks.
