On Tue, 30 Apr 2024 at 20:00, Puranjay Mohan <puranjay@xxxxxxxxxx> wrote: > > Inline the calls to bpf_get_smp_processor_id() in the riscv bpf jit. > > RISCV saves the pointer to the CPU's task_struct in the TP (thread > pointer) register. This makes it trivial to get the CPU's processor id. > As thread_info is the first member of task_struct, we can read the > processor id from TP + offsetof(struct thread_info, cpu). > > RISCV64 JIT output for `call bpf_get_smp_processor_id` > ====================================================== > > Before After > -------- ------- > > auipc t1,0x848c ld a5,32(tp) > jalr 604(t1) > mv a5,a0 > > Benchmark using [1] on Qemu. > > ./benchs/run_bench_trigger.sh glob-arr-inc arr-inc hash-inc > > +---------------+------------------+------------------+--------------+ > | Name | Before | After | % change | > |---------------+------------------+------------------+--------------| > | glob-arr-inc | 1.077 ± 0.006M/s | 1.336 ± 0.010M/s | + 24.04% | > | arr-inc | 1.078 ± 0.002M/s | 1.332 ± 0.015M/s | + 23.56% | > | hash-inc | 0.494 ± 0.004M/s | 0.653 ± 0.001M/s | + 32.18% | > +---------------+------------------+------------------+--------------+ > > NOTE: This benchmark includes changes from this patch and the previous > patch that implemented the per-cpu insn. > > [1] https://github.com/anakryiko/linux/commit/8dec900975ef > > Signed-off-by: Puranjay Mohan <puranjay@xxxxxxxxxx> > --- For non-riscv bits (& fwiw): Acked-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
