On Mon, Jul 28, 2025 at 03:22:49PM +0800, Menglong Dong wrote: > 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
I meassured bit less speed up, but still great kprobe-multi-all: 3.565 ± 0.047M/s kprobe-multi-all: 11.553 ± 0.458M/s could you add kretprobe-multi-all bench as well? thanks, jirka > 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 > >
