netdev - Re: [EXT] Re: [net-next PATCH 0/2] Introduce mbox tracepoints for Octeontx2

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Date:   Thu, 17 Sep 2020 08:04:45 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     sundeep subbaraya <sundeep.lkml@...il.com>
Cc:     Jakub Kicinski <kuba@...nel.org>,
        Sunil Kovvuri Goutham <sgoutham@...vell.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Subbaraya Sundeep Bhatta <sbhatta@...vell.com>
Subject: Re: [EXT] Re: [net-next PATCH 0/2] Introduce mbox tracepoints for
 Octeontx2

Wed, Sep 16, 2020 at 07:19:36PM CEST, sundeep.lkml@...il.com wrote:
>On Wed, Sep 16, 2020 at 4:04 PM Jiri Pirko <jiri@...nulli.us> wrote:
>>
>> Mon, Sep 07, 2020 at 12:59:45PM CEST, sundeep.lkml@...il.com wrote:
>> >Hi Jakub,
>> >
>> >On Sat, Sep 5, 2020 at 2:07 AM Jakub Kicinski <kuba@...nel.org> wrote:
>> >>
>> >> On Fri, 4 Sep 2020 12:29:04 +0000 Sunil Kovvuri Goutham wrote:
>> >> > > >No, there are 3 drivers registering to 3 PCI device IDs and there can
>> >> > > >be many instances of the same devices. So there can be 10's of instances of
>> >> > > AF, PF and VFs.
>> >> > >
>> >> > > So you can still have per-pci device devlink instance and use the tracepoint
>> >> > > Jakub suggested.
>> >> > >
>> >> >
>> >> > Two things
>> >> > - As I mentioned above, there is a Crypto driver which uses the same mbox APIs
>> >> >   which is in the process of upstreaming. There also we would need trace points.
>> >> >   Not sure registering to devlink just for the sake of tracepoint is proper.
>> >> >
>> >> > - The devlink trace message is like this
>> >> >
>> >> >    TRACE_EVENT(devlink_hwmsg,
>> >> >      . . .
>> >> >         TP_printk("bus_name=%s dev_name=%s driver_name=%s incoming=%d type=%lu buf=0x[%*phD] len=%zu",
>> >> >                   __get_str(bus_name), __get_str(dev_name),
>> >> >                   __get_str(driver_name), __entry->incoming, __entry->type,
>> >> >                   (int) __entry->len, __get_dynamic_array(buf), __entry->len)
>> >> >    );
>> >> >
>> >> >    Whatever debug message we want as output doesn't fit into this.
>> >>
>> >> Make use of the standard devlink tracepoint wherever applicable, and you
>> >> can keep your extra ones if you want (as long as Jiri don't object).
>> >
>> >Sure and noted. I have tried to use devlink tracepoints and since it
>> >could not fit our purpose I used these.
>>
>> Why exactly the existing TP didn't fit your need?
>>
>Existing TP has provision to dump skb and trace error strings with
>error code but
>we are trying to trace the entire mailbox flow of the AF/PF and VF
>drivers. In particular
>we trace the below:
>    message allocation with message id and size at initiator.
>    number of messages sent and total size.
>    check message requester id, response id and response code after
>reply is received.
>    interrupts happened on behalf of mailboxes in the entire process
>with source and receiver of interrupt along with isr status.
>    error like initiator timeout waiting for response.
>  All the above are relevant and are required for Octeontx2 only hence
>used own tracepoints.

You can still use devlink_hwmsg for the actual data exchanged between
the driver and hw. For the rest, you can have driver-specific TPs.


>
>Thanks,
>Sundeep
>
>> >
>> >Thanks,
>> >Sundeep