[dpdk-dev] [PATCH 3/5] doc: add cycles per packet in testpmd user guide

[Jerin Jacob]

On Thu, May 7, 2020 at 3:30 AM Dharmik Thakkar <dharmik.thakkar at arm.com> wrote:
>
> Update documentation for 'show fwd' testpmd runtime function to show
> CPU cycles/packet example.
>
> Signed-off-by: Dharmik Thakkar <dharmik.thakkar at arm.com>
> Reviewed-by: Honnappa Nagarahalli <honnappa.nagarahalli at arm.com>
> Reviewed-by: Phil Yang <phil.yang at arm.com>
> ---
>  doc/guides/testpmd_app_ug/testpmd_funcs.rst | 51 +++++++++++++--------
>  1 file changed, 31 insertions(+), 20 deletions(-)
>
> diff --git a/doc/guides/testpmd_app_ug/testpmd_funcs.rst b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> index a360ecccfd3f..2e565ccdbcd4 100644
> --- a/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> +++ b/doc/guides/testpmd_app_ug/testpmd_funcs.rst
> @@ -351,26 +351,37 @@ Example for the io forwarding engine, with some packet drops on the tx side::
>
>     testpmd> show fwd stats all
>
> -     ------- Forward Stats for RX Port= 0/Queue= 0 -> TX Port= 1/Queue= 0 -------
> -     RX-packets: 274293770      TX-packets: 274293642      TX-dropped: 128
> -
> -     ------- Forward Stats for RX Port= 1/Queue= 0 -> TX Port= 0/Queue= 0 -------
> -     RX-packets: 274301850      TX-packets: 274301850      TX-dropped: 0
> -
> -     ---------------------- Forward statistics for port 0  ----------------------
> -     RX-packets: 274293802      RX-dropped: 0             RX-total: 274293802
> -     TX-packets: 274301862      TX-dropped: 0             TX-total: 274301862
> -     ----------------------------------------------------------------------------
> -
> -     ---------------------- Forward statistics for port 1  ----------------------
> -     RX-packets: 274301894      RX-dropped: 0             RX-total: 274301894
> -     TX-packets: 274293706      TX-dropped: 128           TX-total: 274293834
> -     ----------------------------------------------------------------------------
> -
> -     +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
> -     RX-packets: 548595696      RX-dropped: 0             RX-total: 548595696
> -     TX-packets: 548595568      TX-dropped: 128           TX-total: 548595696
> -     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> +     ------- Forward Stats for RX Port= 0/Queue= 0 -> TX Port= 1/Queue= 0 -------
> +     RX-packets: 43536504       TX-packets: 43536488       TX-dropped: 0
> +
> +     ------- Forward Stats for RX Port= 1/Queue= 0 -> TX Port= 0/Queue= 0 -------
> +     RX-packets: 149738504      TX-packets: 149738504      TX-dropped: 0
> +
> +     ------- Forward Stats for RX Port= 1/Queue= 1 -> TX Port= 0/Queue= 1 -------
> +     RX-packets: 149753052      TX-packets: 149753052      TX-dropped: 0
> +
> +     ---------------------- Forward statistics for port 0  ----------------------
> +     RX-packets: 43538881       RX-dropped: 72            RX-total: 43538953
> +     TX-packets: 299491753      TX-dropped: 0             TX-total: 299491753
> +     ----------------------------------------------------------------------------
> +
> +     ---------------------- Forward statistics for port 1  ----------------------
> +     RX-packets: 299493085      RX-dropped: 8357          RX-total: 299501442
> +     TX-packets: 43539683       TX-dropped: 0             TX-total: 43539683
> +     ----------------------------------------------------------------------------
> +
> +     +++++++++++++++ Accumulated forward statistics for all ports+++++++++++++++
> +     RX-packets: 343031966      RX-dropped: 8429          RX-total: 343040395
> +     TX-packets: 343031436      TX-dropped: 0             TX-total: 343031436
> +     ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> +
> +     CPU cycles/packet=14.28 (total cycles=4899533541 / total RX packets=343031966) at 200 MHz
> +
> +.. note::
> +
> +   Measuring CPU cycles/packet requires enabling CONFIG_RTE_TEST_PMD_RECORD_CORE_TX_CYCLES configuration option.

IMO, it a very useful feature for CI/CD and development as we don't
need to see any Traffic generator to see any regression.

I think, enabling CONFIG_RTE_TEST_PMD_RECORD_CORE_TX_CYCLES
configuration is overhead to use in all the environments.

How about adding a "new forward" engine with and remove
CONFIG_RTE_TEST_PMD_RECORD_CORE_TX_CYCLES.
The new forward engine will have
CONFIG_RTE_TEST_PMD_RECORD_CORE_TX_CYCLES code enabled.
So the application can use the forward engine dynamically. aka the
same build works for both cases.


> +   On aarch64 platforms, by default, the cycles are counted using generic counter which runs at a lower frequency than the CPU clock.
> +   To get the cycles/packet at CPU clock frequency, please scale the cycles/packet to CPU clock frequency. Alternatively, use the PMU based cycle counter.
>
>  clear fwd
>  ~~~~~~~~~
> --
> 2.20.1
>