Re: A KernelShark plugin for Xen traces analysis ​

[Giuseppe Eletto <giuseppe.eletto@edu.unito.it>]

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Hi,

As Dario already said, the plugin seems to work well with all the traces we
fed to it.
The largest trace was nearly 500MB, but still it had no trouble showing it.

The only minor troubles I encountered writing the plugin is with the
different data
types between KShark and XenTrace: for example regarding the "event_id"
field of
the "struct kshark_entry" structure which in KShark has type "int16_t"
while XenTrace
has events of the type "uint32_t" at 28 bits.
But since there are functions like "get_event_id" these differences can be
bypassed without seemingly creating problems.

So yes, the plugin is still a prototype. The main purpose so far was to
create
something that works: in fact, as mr. @Andrew_Cooper pointed out, the
couple
"dom:vcpu" is still displayed as a HEX number without any kind of
formatting.
This is because at the moment I have copied the same formatting as the
"xentrace_format" tool.
So a future plan for updating this plugin could be to improve its output.

As for the tutorial, I wouldn't mind trying, but right now I'm busy writing
the thesis for the graduation...

Kind regards,
Giuseppe Eletto.

Il giorno mer 14 apr 2021 alle ore 11:26 Yordan Karadzhov (VMware) <
y.karadz@gmail.com> ha scritto:

> Hi Giuseppe,
>
> It is great to see such progress in the development of the Xen plugin.
>
> Can you share with us what are your plans for continuing this work. Is
> this a first prototype of the plugin, or it is an almost final version?
>
> I was also thinking that maybe you can prepare a short tutorial on
> writing KernelShark plugins for data inputs. You have the best
> experience for this task, since you are the first to develop an external
> plugin. Ideally, this can even turn into a talk that you can give at
> some open source event.
> What do you think?
>
> Best,
> Yordan
>
>
> On 13.04.21 г. 17:28, Giuseppe Eletto wrote:
> > Hello,
> > I want to share with you a new plugin developed by me, under the
> > supervision of Dario Faggioli, which allows the new version of
> KernelShark
> > (the v2-beta) to open and view the Xen traces created using the
> "xentrace" tool.
> >
> > In fact, KernelShark is a well known tool for graphical visualization
> > Linux kernel traces, obtained via "ftrace" and "trace-cmd". Anyway thanks
> > to its modular architecture, it is now possible to implement plugins
> which
> > open and display traces with arbitrary format, for example, as in in
> > this case, traces of the Xen hypervisor.
> >
> > For more information on how to build the plugin and/or
> > to view the source code I leave the repository below:
> > https://github.com/giuseppe998e/kernelshark-xentrace-plugin
> >
> >
> > In short:
> >
> > $ sudo apt install git build-essential libjson-c-dev
> > $ git clone --recurse-submodules
> > https://github.com/giuseppe998e/kernelshark-xentrace-plugin.git
> > $ cd kernelshark-xentrace-plugin/
> > $ make
> >
> > $ export XEN_CPUHZ=3G # Sets the CPU frequency ((G)hz/(M)hz/(K)hz/hz)
> > $ kernelshark -p out/ks-xentrace.so trace.xen
> >
> >
> > You will need the development version of KernelShark, available here:
> > https://git.kernel.org/pub/scm/utils/trace-cmd/kernel-shark.git
> >
> > A screenshot of the plugin in action is available here:
> >
> https://github.com/giuseppe998e/kernelshark-xentrace-plugin/raw/master/.github/img/ks-xentrace.png
> >
> > I'm happy to receive whatever feedback you may have about it,
> > and to answer any question.
> >
> > Kind regards,
> > Giuseppe Eletto.
> >
>

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