Re: [MirageOS-devel] Tracing and profiling blog post

[Thomas Leonard <talex5@xxxxxxxxx>]

On 27 October 2014 10:47, Anil Madhavapeddy <anil@xxxxxxxxxx> wrote:
> On 27 Oct 2014, at 10:42, Thomas Leonard <talex5@xxxxxxxxx> wrote:
>>
>> I've put up a blog post describing the tracing work:
>>
>> http://roscidus.com/blog/blog/2014/10/27/visualising-an-asynchronous-monad/
>>
>> It explains how to read the diagrams, what the various arrows mean and
>> how to instrument your own programs. There are examples from tracing
>> some Mirage unikernels. The viewer should now also work on tablets
>> (pinch to zoom) - though probably very slowly! Let me know if there
>> are any browser compatibility problems...
>
> Great post as always!  My first reaction was wincing at the inefficiency
> of scatter-gather IO.  Perhaps we should indeed expose a copying API to
> minimise the guest VM <-> backend ring traffic...

Wow - impressive speed-reading skills there!

> What are the next steps to get the profiling modules into mirage-dev
> so that we can start sprinkling this in all of our libraries?

I need to make mirage-profile detect whether lwt.tracing is installed
and compile null-op functions if it isn't. The API needs a little
cleaning up too (e.g. note_increase should probably take a counter
object rather than a string), but that shouldn't be much work -
libraries don't need to use many calls to provide useful trace
information.

The API for controlling tracing and the trace format may continue to
change, but that shouldn't break libraries that are just providing
trace data.


-- 
Dr Thomas Leonard        http://0install.net/
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