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Re: [tracecompass-dev] Accessing LTTng-ust cpu_id event field inside an XML state provider

Hi Aleix,

Your message is totally appropriate and this is exactly what this list
is for.

Matthew said it all and I have not much to enhance the explanation, only
maybe to prevent further questions in case you need it, but the context
fields (vpid, vtid, etc) are accessed in XML with

<stateAttribute type="eventField" value="context._vpid" />

Thanks you for highlighting the missing details of the documentation.

Out of curiosity, how did you get started with the XML analyses? Did you
read the Trace Compass documentation, did you find an analysis lying
around to copy-paste from? If so where? We'd like to improve the user
experience of the custom XML analyses (getting started and doing more
complex stuff) and knowing how you learned will help us improve that


On 2018-03-09 09:06 AM, aleix wrote:
> Hello!
> This is my first message on the list, please excuse me if it is not
> appropiate.
> I'm writing a custom state provider in XML and I'm wondering
> how can I access the CPU id of a user space event within the state
> provider. I have tried with:
>   <stateAttribute type="eventField" value="cpu_id" />
> But it is not found. The babeltrace output of the LTTng trace shows me:
> [17:33:44.238047390] (+0.000000366) xeon08 nanos:ust_task_label: { cpu_id = 24 }, { vpid = 24505, vtid = 24557, procname = "cholesky-weakit" }, { task_id = 1, task_label = "dgemm" }
> so the "cpu_id" field is present, although is not one of the
> user-defined tracepoint parameters such as "task_id" or "task_label".
> Any hint?
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