Re: [EXPERIENCE] My experience on using perf record BPF filter on a real usecase

[Wangnan (F)]

On 2015/6/10 14:42, Alexei Starovoitov wrote:
> 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?

Looks good. Thank you for your information!


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