On 2025/7/15 03:52, Alexei Starovoitov wrote:
On Thu, Jul 10, 2025 at 12:10 AM Menglong Dong <menglong8.dong@xxxxxxxxx> wrote:} else { - addr = kallsyms_lookup_name(tname); + ret = bpf_lookup_attach_addr(NULL, tname, &addr); }Not sure why your benchmarking doesn't show the difference, but above is a big regression. kallsyms_lookup_name() is a binary search whereas your bpf_lookup_attach_addr() is linear. You should see a massive degradation in multi-kprobe attach speeds.
Hi, Alexei. Like I said above, the benchmarking does have a difference for the symbol in the modules, which makes the attachment time increased from 0.135543s to 0.176904s for 8631 symbols. As the symbols in the modules is not plentiful, which makes the overhead slight(or not?). But for the symbol in vmlinux, bpf_lookup_attach_addr() will call kallsyms_on_each_match_symbol(), which is also a binary search, so the benchmarking has no difference, which makes sense. I thought we don't need this patch after the pahole fixes this problem. Should I send a V4? Thanks! Menglong Dong
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