Re: [PATCH v2] bpf: BPF based latency tracing

From: Daniel Wagner
Date: Mon Jun 22 2015 - 03:34:44 EST

On 06/20/2015 10:14 AM, Daniel Borkmann wrote:
> I think it would be useful to perhaps have two options:
> 1) User specifies a specific CPU and gets one such an output above.

Good point. Will do.

> 2) Summary view, i.e. to have the samples of each CPU for comparison
> next to each other in columns and maybe the histogram view a bit
> more compressed (perhaps summary of all CPUs).

I agree, the current view is not really optimal. I'll look into this as

Alexei indicated that he is working on per-cpu variables support. I
think that would be extremely useful to drop the hard coded limit of
CPUs and turning this sample code into some more generic code.

> Anyway, it's sample code people can go with and modify individually.

I am interested to turn this code into a more useful tool. Though I
think I miss some background information why this code is kept as
samples. Obviously, there is the API and ARCH dependency. As long as an
API change can reliable be detected I don't see a real show stopper.
Maybe I am too naive. Furthermore I expected that trace_preempt_[on|off]
wont change that often.

> Acked-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>

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