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 rhltable 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 : 902.387 ± 0.762M/s kernel-count : 427.356 ± 0.368M/s syscall-count : 30.830 ± 0.016M/s fentry : 135.554 ± 0.064M/s fexit : 68.317 ± 0.218M/s fmodret : 70.633 ± 0.275M/s rawtp : 193.404 ± 0.346M/s tp : 80.236 ± 0.068M/s kprobe : 55.200 ± 0.359M/s kprobe-multi : 54.304 ± 0.092M/s kprobe-multi-all: 54.487 ± 0.035M/s << look this kretprobe : 22.381 ± 0.075M/s kretprobe-multi: 27.926 ± 0.034M/s The benchmark of "kprobe-multi-all" increase from 6.283M/s to 54.487M/s. The locking is not handled properly in the first patch. In the fprobe_entry, we should use RCU when we access the rhlist_head. However, we can't use RCU for __fprobe_handler, as it can sleep. In the origin logic, it seems that the usage of hlist_for_each_entry_from_rcu() is not protected by rcu_read_lock neither, isn't it? I don't know how to handle this part ;( Menglong Dong (4): fprobe: use rhltable for fprobe_ip_table selftests/bpf: move get_ksyms and get_addrs to trace_helpers.c selftests/bpf: skip recursive functions for kprobe_multi selftests/bpf: add benchmark testing for kprobe-multi-all include/linux/fprobe.h | 2 +- kernel/trace/fprobe.c | 141 ++++++----- 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, 348 insertions(+), 282 deletions(-) -- 2.50.1
