[dpdk-dev] [PATCH v4 2/2] doc: add guide for debug and troubleshoot

[Kovacevic, Marko]

After checking the patch again I found a few spelling mistakes

> Add user guide on debug and troubleshoot for common issues and
> bottleneck found in sample application model.
> 
> Signed-off-by: Vipin Varghese <vipin.varghese at intel.com>
> Acked-by: Marko Kovacevic <marko.kovacevic at intel.com>
> ---
>  doc/guides/howto/debug_troubleshoot_guide.rst | 375
> ++++++++++++++++++
>  doc/guides/howto/index.rst                    |   1 +
>  2 files changed, 376 insertions(+)
>  create mode 100644 doc/guides/howto/debug_troubleshoot_guide.rst
>

<...>
 
receieve / receive

> +    -  If stats for RX and drops updated on same queue? check receieve
> thread
> +    -  If packet does not reach PMD? check if offload for port and queue
> +       matches to traffic pattern send.
> +

<...>

Offlaod/ offload
 
> +    -  Is the packet multi segmented? Check if port and queue offlaod is set.
> +
> +Are there object drops in producer point for ring?
> +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

<...>

sufficent / sufficient 

> +    -  Are drops on specific socket? If yes check if there are sufficent
> +       objects by rte_mempool_get_count() or rte_mempool_avail_count()
> +    -  Is 'rte_mempool_get_count() or rte_mempool_avail_count()' zero?
> +       application requires more objects hence reconfigure number of
> +       elements in rte_mempool_create().
> +    -  Is there single RX thread for multiple NIC? try having multiple
> +       lcore to read from fixed interface or we might be hitting cache
> +       limit, so increase cache_size for pool_create().
> +

Sceanrios/ scenarios
 
> +#. Is performance low for some sceanrios?
> +    -  Check if sufficient objects in mempool by rte_mempool_avail_count()
> +    -  Is failure seen in some packets? we might be getting packets with
> +       'size > mbuf data size'.
> +    -  Is NIC offload or application handling multi segment mbuf? check the
> +       special packets are continuous with rte_pktmbuf_is_contiguous().
> +    -  If there separate user threads used to access mempool objects, use
> +       rte_mempool_cache_create() for non DPDK threads.

debuging / debugging 

> +    -  Is the error reproducible with 1GB hugepage? If no, then try debuging
> +       the issue with lookup table or objects with rte_mem_lock_page().
> +
> +.. note::
> +  Stall in release of MBUF can be because

<...>

softwre / software

> +    -  If softwre crypto is in use, check if the CRYPTO Library is build with
> +       right (SIMD) flags or check if the queue pair using CPU ISA for
> +       feature_flags AVX|SSE|NEON using rte_cryptodev_info_get()

Assited/ assisted 

> +    -  If its hardware assited crypto showing performance variance? Check if
> +       hardware is on same NUMA socket as queue pair and session pool.
> +

<...>

exceeeding / exceeding 

> +       core? registered functions may be exceeeding the desired time slots
> +       while running on same service core.
> +    -  Is function is running on RTE core? check if there are conflicting
> +       functions running on same CPU core by rte_thread_get_affinity().
> +

<...>

> +#. Where to capture packets?
> +    -  Enable pdump in primary to allow secondary to access queue-pair for
> +       ports. Thus packets are copied over in RX|TX callback by secondary
> +       process using ring buffers.
> +    -  To capture packet in middle of pipeline stage, user specific hooks
> +       or callback are to be used to copy the packets. These packets can

secodnary / secondary 

> +       be shared to secodnary process via user defined custom rings.
> +
> +Issue still persists?
> +~~~~~~~~~~~~~~~~~~~~~
> +
> +#. Are there custom or vendor specific offload meta data?
> +    -  From PMD, then check for META data error and drops.
> +    -  From application, then check for META data error and drops.
> +#. Is multiprocess is used configuration and data processing?
> +    -  Check enabling or disabling features from secondary is supported or
> not?

Obejcts/ objects 

> +#. Is there drops for certain scenario for packets or obejcts?
> +    -  Check user private data in objects by dumping the details for debug.
> +
<...>

Thanks,
Marko K