On Thu, Oct 22, 2015 at 11:12:16AM +0800, Wangnan (F) wrote: > On 2015/10/22 11:09, Alexei Starovoitov wrote: > >On 10/21/15 6:56 PM, Wangnan (F) wrote: > >>>One alternative solution I can image is to attach a BPF program > >>>at sampling like kprobe, and return 0 if we don't want sampling > >>>take action. Thought? > >> > >>Do you think attaching BPF programs to sampling is an acceptable idea? > > > >If you mean to extend 'filter' concept to sampling events? > >So instead of soft_disable of non-local events, you'll attach bpf > >program to sampling events and use map lookup to decide whether > >to filter out or not such sampling event? > > Yes.
One could overload or stack the overflow handler I suppose. But this would be in line with the software/tracepoint events calling eBPF muck on trigger, right? > >What pt_regs would be in such case? > Sampling is based on interruption. We can use pt_reg captured by the IRQ > handler, s/IRQ/NMI/ Also, we 'edit' the pt_regs on the way down to the overflow handler as sometimes 'better' information can be had from PMU state. But a pt_regs is available there. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
