[dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[Utkarsh Pandey]

Hi,

I am trying to test the newly added DPDK Trace Library in DPDK 20.08.

I created a DPDK trace point as follows:

Defined the trace point in the header file:

#################################################
#include <rte_trace_point.h>

RTE_TRACE_POINT(
        app_dpdk_tx_tp,
        RTE_TRACE_POINT_ARGS(const char *str),
        rte_trace_point_emit_string(str);
)
##################################################

Registered the trace point as follows:

######################################################
#include <rte_trace_point_register.h>
#include "dpdk_UDP_trace_Tx.h"

  RTE_TRACE_POINT_REGISTER(app_dpdk_tx_tp, app.dpdk.tx.tp)
######################################################

In my application, I try to emit simple string using the above trace-point:


*app_dpdk_tx_tp("Test trace string");*
I run the program as follows:

 $sudo ./build/app/udpTx -n 4 -l 2  --trace-dir=/home/upandey/dpdk-traces
--trace=.*

The resulting trace file when analyzed using babeltrace does contain traces
from DPDK libraries but it does not have the traces which I have added to
the application. I have tried running with the "discard" option as well,
but the result is the same.

I have the following questions:
1. Am I missing something in declaring and registering the trace-point?
2. Do I have to enable some config parameters in DPDK to be able to get the
user-defined traces?

Thanks and regards,
Utkarsh Pandey

Re: [dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[Sanjit Kumar]

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Hi,

Thank you for your email. I am already compiling the application that has
the tracepoint register code with -DALLOW_EXPERIMENTAL_API but still am
running into this issue. Are there any other possible causes for this
behaviour? Thanks again.

Regards,
Sanjit Kumar

On Fri, Oct 27, 2023 at 1:11 AM David Marchand <david.marchand@redhat.com>
wrote:

> Hello,
>
> Copying trace framework maintainers.
>
> On Fri, Oct 27, 2023 at 9:48 AM Sanjit Kumar
> <sanjit.kumar@aviznetworks.com> wrote:
> > I am trying to test the usage of the DPDK trace library. I have run into
> the same issue as recounted here -
> https://mails.dpdk.org/archives/users/2020-December/005266.html  - where
> I am able to build and run my DPDK application where I have created and
> registered my custom trace point (verified via rte_trace_dump(stdout) which
> says my traces are 'enabled' - i see the right trace buffer size, trace
> file destination etc). The trace point creation and registration are
> identical to what is mentioned in the program guide using RTE_TRACE_POINT
> in a header file and registering it in my dpdk application via
> RTE_TRACE_POINT_REGISTER macro.
> >
> > What I notice are as follows:
> >
> > 1. The program builds and runs as intended.
> > 2. The trace files are generated in the correct destination directory.
> > 3. On using trace=.*  ----> I see a huge list of traces on viewing the
> trace file with babeltrace - but do not see my custom trace point. I also
> do not see any trace output from my dpdk application if I reuse DPDK
> library traces ( eg: rte_eal_trace_thread_lcore_ready ) instead of defining
> my own custom traces.
> > 4. On using trace=<regex for traces used in my application> i do not see
> any trace output just used inside my application.
> >
> > I think the above observations suggest that the issue might be in
> configuring my DPDK application to recognize and create trace output
> properly. However the rte_trace_dump output suggests that trace is enabled
> here.
> >
> > What I would like to know is similar to utkarsh's question:
> > Is there anything I am missing in configuring my application to
> recognize traces? If so can you please point it out?
>
> I think a hint was posted later, about this topic.
> Did you compile your application tracepoint register code with
> -DALLOW_EXPERIMENTAL_API ?
>
> If you confirm it solves your issue, we need to enhance the trace
> framework documentation.
>
>
> --
> David Marchand
>
>

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Re: [dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[David Marchand]

Hello,

Copying trace framework maintainers.

On Fri, Oct 27, 2023 at 9:48 AM Sanjit Kumar
<sanjit.kumar@aviznetworks.com> wrote:
> I am trying to test the usage of the DPDK trace library. I have run into the same issue as recounted here - https://mails.dpdk.org/archives/users/2020-December/005266.html  - where I am able to build and run my DPDK application where I have created and registered my custom trace point (verified via rte_trace_dump(stdout) which says my traces are 'enabled' - i see the right trace buffer size, trace file destination etc). The trace point creation and registration are identical to what is mentioned in the program guide using RTE_TRACE_POINT in a header file and registering it in my dpdk application via RTE_TRACE_POINT_REGISTER macro.
>
> What I notice are as follows:
>
> 1. The program builds and runs as intended.
> 2. The trace files are generated in the correct destination directory.
> 3. On using trace=.*  ----> I see a huge list of traces on viewing the trace file with babeltrace - but do not see my custom trace point. I also do not see any trace output from my dpdk application if I reuse DPDK library traces ( eg: rte_eal_trace_thread_lcore_ready ) instead of defining my own custom traces.
> 4. On using trace=<regex for traces used in my application> i do not see any trace output just used inside my application.
>
> I think the above observations suggest that the issue might be in configuring my DPDK application to recognize and create trace output properly. However the rte_trace_dump output suggests that trace is enabled here.
>
> What I would like to know is similar to utkarsh's question:
> Is there anything I am missing in configuring my application to recognize traces? If so can you please point it out?

I think a hint was posted later, about this topic.
Did you compile your application tracepoint register code with
-DALLOW_EXPERIMENTAL_API ?

If you confirm it solves your issue, we need to enhance the trace
framework documentation.


-- 
David Marchand

Re: [dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[Sanjit Kumar]

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Hi,

I am trying to test the usage of the DPDK trace library. I have run into
the same issue as recounted here -
https://mails.dpdk.org/archives/users/2020-December/005266.html
<https://mails.dpdk.org/archives/users/2020-December/005266.html> - where I
am able to build and run my DPDK application where I have created and
registered my custom trace point (verified via rte_trace_dump(stdout) which
says my traces are 'enabled' - i see the right trace buffer size, trace
file destination etc). The trace point creation and registration are
identical to what is mentioned in the program guide using RTE_TRACE_POINT
in a header file and registering it in my dpdk application via
RTE_TRACE_POINT_REGISTER macro.

What I notice are as follows:

1. The program builds and runs as intended.
2. The trace files are generated in the correct destination directory.
3. On using trace=.*  ----> I see a huge list of traces on viewing the
trace file with babeltrace - but do not see my custom trace point. I also
do not see any trace output from my dpdk application if I reuse DPDK
library traces ( eg: rte_eal_trace_thread_lcore_ready ) instead of
defining my own custom traces.
4. On using trace=<regex for traces used in my application> i do not see
any trace output just used inside my application.

I think the above observations suggest that the issue might be in
configuring my DPDK application to recognize and create trace output
properly. However the rte_trace_dump output suggests that trace is enabled
here.

What I would like to know is similar to utkarsh's question:
Is there anything I am missing in configuring my application to recognize
traces? If so can you please point it out?


Thanks and Regards,
Sanjit Kumar

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Re: [dpdk-users] Unable to see traces from a user defined DPDK Tracepoint

[Plague]

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Seeing as this has no reply and I ran into the problem too, I am posting a
solution here.

Because the trace API was (is?) experimental, some of the calls are
translated to RTE_SET_USED(). You need to define ALLOW_EXPERIMENTAL_API in
the caller's source file at the very top.

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