[dpdk-dev] [PATCH] app/testpmd: add profiling for Rx/Tx burst routines

[Slava Ovsiienko]

I think we should compromise: keep existing RTE_TEST_PMD_RECORD_CORE_CYCLES
and extend with runtime switch under this build-time option:

#ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES
if (record_tx)
  .. gather tx related stats...
if (record_rx)
  .. gather rx related stats...
#endif

This is very specific feature, it is needed while debugging and testing datapath
routines, and It seems this feature with appropriate overhead should not be always enabled.
existing build-time configuration options looks OK as for me. 

Bruce, if proposed runtime extension is acceptable - I will update the patch.

WBR,
Slava

> -----Original Message-----
> From: Bruce Richardson <bruce.richardson at intel.com>
> Sent: Friday, June 28, 2019 17:20
> To: Iremonger, Bernard <bernard.iremonger at intel.com>
> Cc: Slava Ovsiienko <viacheslavo at mellanox.com>; dev at dpdk.org; Yigit,
> Ferruh <ferruh.yigit at intel.com>
> Subject: Re: [dpdk-dev] [PATCH] app/testpmd: add profiling for Rx/Tx burst
> routines
> 
> On Fri, Jun 28, 2019 at 02:45:13PM +0100, Iremonger, Bernard wrote:
> > Hi Bruce, Slava,
> >
> > > -----Original Message-----
> > > From: Slava Ovsiienko [mailto:viacheslavo at mellanox.com]
> > > Sent: Thursday, June 27, 2019 5:49 AM
> > > To: Richardson, Bruce <bruce.richardson at intel.com>
> > > Cc: dev at dpdk.org; Iremonger, Bernard <bernard.iremonger at intel.com>;
> > > Yigit, Ferruh <ferruh.yigit at intel.com>
> > > Subject: RE: [dpdk-dev] [PATCH] app/testpmd: add profiling for Rx/Tx
> > > burst routines
> > >
> > > OK, what do you think about this:
> > >
> > > #ifdef RTE_TEST_PMD_RECORD_CORE_CYCLES  if (record_cycle &
> > > RECORD_TX_CORE_CYCLES) {
> > >    .. do measurement stuff ..
> > >  }
> > > #endif
> > >
> > > + add some new command to config in runtime: "set record_cycle 3"
> > >
> > > We keep existing RTE_TEST_PMD_RECORD_CORE_CYCLES, do not
> introduce
> > > new build-time configs and get some new runtime configuring.
> > >
> > > WBR,
> > > Slava
> > >
> > > > -----Original Message-----
> > > > From: Bruce Richardson <bruce.richardson at intel.com>
> > > > Sent: Wednesday, June 26, 2019 16:21
> > > > To: Slava Ovsiienko <viacheslavo at mellanox.com>
> > > > Cc: dev at dpdk.org; bernard.iremonger at intel.com;
> > > > ferruh.yigit at intel.com
> > > > Subject: Re: [dpdk-dev] [PATCH] app/testpmd: add profiling for
> > > > Rx/Tx burst routines
> > > >
> > > > On Wed, Jun 26, 2019 at 01:19:24PM +0000, Slava Ovsiienko wrote:
> > > > > Hi, Bruce
> > > > >
> > > > > Do you mean using "if (core_rx_cycle_enabled) {...}" instead of #ifdef
> ?
> > > > >
> > > > > No, I did not try runtime control settings.
> > > > > Instead I compared performance with all RECORD_CORE_XX_CYCLES
> > > > options
> > > > > enabled/disabled builds and have seen the ~1-2% performance
> > > > > difference
> > > > on my setups (mainly fwd txonly with retry).
> > > > > So, ticks measuring is not free.
> > > > >
> > > > > With best regards,
> > > > > Slava
> > > > >
> > > > Yes, I realise that measuring ticks is going to have a performance
> impact.
> > > > However, what I was referring to was exactly the former - using an "if"
> > > > rather than an "ifdef". I would hope with ticks disable using this
> > > > option shows no perf impact, and we can reduce the use of
> > > > build-time
> > > configs.
> > > >
> > > > /Bruce
> >
> > Given that  RTE_TEST_PMD_RECORD_CORE_CYCLES is already in the
> config file.
> > I think it is better to be consistent and add the new RECORD macros there.
> >
> > Would it be reasonable to have runtime settings available as well?
> >
> That configuration option is only present right now for the make builds, so I'd
> like to see it replaced with a runtime option rather than see about adding
> more config options to the meson build. The first step should be to avoid
> adding more config options and just look to use dynamic ones. Ideally the
> existing build option should be replaced at the same time.
> 
> /Bruce