Re: [PATCH RFC v4 net-next 00/26] BPF syscall, maps, verifier, samples, llvm

[Brendan Gregg]

On Wed, Aug 13, 2014 at 12:57 AM, Alexei Starovoitov <ast@xxxxxxxxxxxx> wrote:
[...]
> Tracing use case got some improvements as well. Now eBPF programs can be
> attached to tracepoint, syscall, kprobe and C examples are more usable:
> ex1_kern.c - demonstrate how programs can walk in-kernel data structures
> ex2_kern.c - in-kernel event accounting and user space histograms
> See patch #25

This is great, thanks! I've been using this new support, and
successfully ported an an older tool of mine (bitesize) to eBPF. I was
using the block:block_rq_issue tracepoint, and performing a custom
in-kernel histogram, like in the ex2_kern.c example, for I/O size.

I also did some quick overhead testing and found eBPF with JIT to be
relatively fast. (I'd share numbers but it's platform specific.) The
syscall tracepoints were a bit slower than hoped, for what I think is
a well known issue.

Are there thoughts in general for how this might be used for embedded
devices, where installing clang/llvm might be prohibitive? Compile on
another system and move the binaries over? thanks,

Brendan
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/