[PATCH bpf-next 0/4] fprobe: use rhashtable for fprobe_ip_table

[Menglong Dong <menglong8.dong@gmail.com>]

For now, the budget of the hash table that is used for fprobe_ip_table is
fixed, which is 256, and can cause huge overhead when the hooked functions
is a huge quantity.

In this series, we use rhashtable for fprobe_ip_table to reduce the
overhead.

Meanwhile, we also add the benchmark testcase "kprobe-multi-all", which
will hook all the kernel functions during the testing. Before this series,
the performance is:
  usermode-count :  875.380 ± 0.366M/s 
  kernel-count   :  435.924 ± 0.461M/s 
  syscall-count  :   31.004 ± 0.017M/s 
  fentry         :  134.076 ± 1.752M/s 
  fexit          :   68.319 ± 0.055M/s 
  fmodret        :   71.530 ± 0.032M/s 
  rawtp          :  202.751 ± 0.138M/s 
  tp             :   79.562 ± 0.084M/s 
  kprobe         :   55.587 ± 0.028M/s 
  kprobe-multi   :   56.481 ± 0.043M/s 
  kprobe-multi-all:    6.283 ± 0.005M/s << look this
  kretprobe      :   22.378 ± 0.028M/s 
  kretprobe-multi:   28.205 ± 0.025M/s

With this series, the performance is:
  usermode-count :  897.083 ± 5.347M/s 
  kernel-count   :  431.638 ± 1.781M/s 
  syscall-count  :   30.807 ± 0.057M/s 
  fentry         :  134.803 ± 1.045M/s 
  fexit          :   68.763 ± 0.018M/s 
  fmodret        :   71.444 ± 0.052M/s 
  rawtp          :  202.344 ± 0.149M/s 
  tp             :   79.644 ± 0.376M/s 
  kprobe         :   55.480 ± 0.108M/s 
  kprobe-multi   :   57.302 ± 0.119M/s 
  kprobe-multi-all:   57.855 ± 0.144M/s << look this
  kretprobe      :   22.265 ± 0.023M/s 
  kretprobe-multi:   27.740 ± 0.023M/s

The benchmark of "kprobe-multi-all" increase from 6.283M/s to 57.855M/s.

Menglong Dong (4):
  fprobe: use rhashtable
  selftests/bpf: move get_ksyms and get_addrs to trace_helpers.c
  selftests/bpf: add benchmark testing for kprobe-multi-all
  selftests/bpf: skip recursive functions for kprobe_multi

 include/linux/fprobe.h                        |   2 +-
 kernel/trace/fprobe.c                         | 144 ++++++-----
 tools/testing/selftests/bpf/bench.c           |   2 +
 .../selftests/bpf/benchs/bench_trigger.c      |  30 +++
 .../selftests/bpf/benchs/run_bench_trigger.sh |   2 +-
 .../bpf/prog_tests/kprobe_multi_test.c        | 220 +----------------
 tools/testing/selftests/bpf/trace_helpers.c   | 230 ++++++++++++++++++
 tools/testing/selftests/bpf/trace_helpers.h   |   3 +
 8 files changed, 351 insertions(+), 282 deletions(-)

-- 
2.50.1