Re: [dpdk-dev] [EXT] Re: [PATCH] eal: add telemetry callbacks for memory info

[Harman Kalra <hkalra@marvell.com>]

> -----Original Message-----
> From: Bruce Richardson <bruce.richardson@intel.com>
> Sent: Monday, September 20, 2021 9:27 PM
> To: Harman Kalra <hkalra@marvell.com>
> Cc: dev@dpdk.org; ciara.power@intel.com; Anatoly Burakov
> <anatoly.burakov@intel.com>
> Subject: [EXT] Re: [PATCH] eal: add telemetry callbacks for memory info
> 
> External Email
> 
> ----------------------------------------------------------------------
> On Wed, Sep 15, 2021 at 03:23:36PM +0530, Harman Kalra wrote:
> > Registering new telemetry callbacks to dump named (memzones) and
> > unnamed (malloc) memory information to a file provided as an argument.
> >
> > Example:
> > Connecting to /var/run/dpdk/rte/dpdk_telemetry.v2
> > {"version": "DPDK 21.08.0", "pid": 34075, "max_output_len": 16384}
> > Connected to application: "dpdk-testpmd"
> > --> /eal/malloc_dump,/tmp/malloc_dump
> > {"/eal/malloc_dump": {"Malloc elements file: ": "/tmp/malloc_dump"}}
> > -->
> > --> /eal/malloc_info,/tmp/info
> > {"/eal/malloc_info": {"Malloc stats file: ": "/tmp/info"}}
> > -->
> > -->
> > --> /eal/memzone_dump,/tmp/memzone_info
> > {"/eal/memzone_dump": {"Memzones count: ": 11, \ "Memzones info file:
> > ": "/tmp/memzone_info"}}
> >
> > Signed-off-by: Harman Kalra <hkalra@marvell.com>
> > ---
> 
> For this info, why not just send the data out as telemetry data rather than
> writing files on the filesystem containing it? If the info is too large to dump it
> all in a single go, a shortened form could be sent via some form of list call,
> and additional calls could be used to provide more detail on specific items in
> the list.
> 
>  Also, this seems more a debugging operation than a telemetry one, though I
> don't have a strong objection to the info being exported as telemetry directly
> (just not via filesystem).
> 
> Regards,
> /Bruce


Hi Bruce,

Thanks for reviewing the patch.
I have implemented these telemetry commands as a wrapper which uses existing malloc/memzone debug APIs to
collect the debug information, these debug APIs are implemented in the way that they accept a file pointer/stdout.
to get the information.

As a solution either  I should make changes to these debug APIs to accept a buffer also? Or other way could be get
the info dumped into a file, and inside telemetry command parse and convert the info into json format and send it.
But its lot of debug information so will require multiple iterations as you suggested. But on client (peer) side one
will have to again convert json to retrieve the info. 

Just for my understanding, what drawback do you see in dumping the information to a file? Because on peer side
It is very convenient to read the information from dumped file and use it.

Thanks
Harman