Re: [dpdk-dev] [RFC v2 1/3] ethdev: add the API for getting trace information

["Wang, Haiyue" <haiyue.wang@intel.com>]

> -----Original Message-----
> From: Stephen Hemminger [mailto:stephen@networkplumber.org]
> Sent: Tuesday, August 13, 2019 11:25
> To: Wang, Haiyue <haiyue.wang@intel.com>
> Cc: dev@dpdk.org
> Subject: Re: [dpdk-dev] [RFC v2 1/3] ethdev: add the API for getting trace information
> 
> On Tue, 13 Aug 2019 11:06:10 +0800
> Haiyue Wang <haiyue.wang@intel.com> wrote:
> 
> > Enhance the PMD to support retrieving trace information like
> > Rx/Tx burst selection etc.
> >
> > Signed-off-by: Haiyue Wang <haiyue.wang@intel.com>
> > ---
> >  lib/librte_ethdev/rte_ethdev.c      | 18 ++++++++++++++++++
> >  lib/librte_ethdev/rte_ethdev.h      |  9 +++++++++
> >  lib/librte_ethdev/rte_ethdev_core.h |  4 ++++
> >  3 files changed, 31 insertions(+)
> >
> > diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c
> > index 17d183e..6098fad 100644
> > --- a/lib/librte_ethdev/rte_ethdev.c
> > +++ b/lib/librte_ethdev/rte_ethdev.c
> > @@ -4083,6 +4083,24 @@ rte_eth_tx_queue_info_get(uint16_t port_id, uint16_t queue_id,
> >  }
> >
> >  int
> > +rte_eth_trace_info_get(uint16_t port_id, uint16_t queue_id,
> > +		       enum rte_eth_trace type, char *buf, int sz)
> > +{
> > +	struct rte_eth_dev *dev;
> > +
> > +	RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV);
> > +
> > +	if (buf == NULL)
> > +		return -EINVAL;
> > +
> > +	dev = &rte_eth_devices[port_id];
> > +
> > +	RTE_FUNC_PTR_OR_ERR_RET(*dev->dev_ops->trace_info_get, -ENOTSUP);
> > +
> > +	return dev->dev_ops->trace_info_get(dev, queue_id, type, buf, sz);
> 
> What if queueid is out of bounds?

Some trace may not need queueid, so skip it check here, make it a little
flexible.

> 
> The bigger problem is that this information is like a log message
> and unstructured, which makes it device specific and useless for automation.
> 
> Why not just keep it in the log like it is now?

Yes, log is good now (but need run with extra options). This patch works like
run time debug tool, it identify the code running status. Not for automation
now. But if we want this kind of things, hook the code point, define a rule
to format the message.

> 
> >  int rte_eth_tx_queue_info_get(uint16_t port_id, uint16_t queue_id,
> >  	struct rte_eth_txq_info *qinfo);
> >
> > +int
> > +rte_eth_trace_info_get(uint16_t port_id, uint16_t queue_id,
> > +	enum rte_eth_trace type, char *buf, int sz);
> > +
> 
> You didn't run checkpatch, otherwise you would have seen complaints
> about not listing API as experimental.
> 

./devtools/checkpatches.sh ?

3/3 valid patches


> Also the API would have to be in the map file as well.
> 
> Docbook comments are also missing.
> 
> 

This is rough draft, so show the code firstly. ;-)