Messages in this thread | | | Date | Tue, 09 Jun 2015 23:42:08 -0700 | From | Alexei Starovoitov <> | Subject | Re: [EXPERIENCE] My experience on using perf record BPF filter on a real usecase |
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On 6/4/15 3:17 AM, Wangnan (F) wrote: > Hi all, > > I'd like to share my exprience on using 'perf record' BPF filter in a > real usecase to show the power and shortcome in my patch series:
thanks for sharing!
> Here is another inconvenience. Currently I only concern on write > syscall issued by iozone. However, without '-a' I'm unable to collect > information of the locker. If I want to filter sys_{enter,exit}_write > belong to iozone out using eBPF, I need to implement another function > like BPF_FUNC_git_comm. Another method is to use perf '--filter' after > the two events. However it looks strange to use two filter mechanisms > together. This time I choose to do filtering offline using perf script.
that doesn't sound clean. btw, I've been playing for a while with bpf_get_current_task_info() helper: https://git.kernel.org/cgit/linux/kernel/git/ast/bpf.git/commit/?id=c5453ffa107ddf95a91920cc947bb8bf9eab16d6 I think it's a better mechanism. The user can get pid only via: u32 pid = 0; bpf_get_current_task_info(&pid, sizeof(pid)); or full pid + comm + future fields via full 'struct bpf_task_info' Thoughts?
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