01/02/2023 11:58, Andrew Rybchenko: > On 2/1/23 13:48, Jerin Jacob wrote: > > On Wed, Feb 1, 2023 at 2:59 PM Andrew Rybchenko > > <andrew.rybche...@oktetlabs.ru> wrote: > >> Frankly speaking I don't understand why default value is so > >> important if we have a way to change it. Reasons should be > >> really strong to change existing defaults. > > > > The only reason is, typically testpmd will be used performance > > benchmarking as an industry standard. It is difficult to tell/educate > > the QA or customers > > that, "BTW if you need to get better performance add more flag to > > testpmd command line".
I disagree. When you do performance benchmark, you tune settings accordingly. > > To make that worst, only some PMD needs to give the additional > > parameter to get better number. > > And also, testpmd usage will be treated as application modeling. > > > > Since this feature only used on sfc and cnxk driver, What is the > > situation with sfc driver? > > Keeping it as negotiated and not use the feature, will impact the per > > core performance of sfc or > > is it just PCI bandwidth thing which really dont show any difference in > > testpmd? > > Yes, sfc could run faster if no Rx metadata are negotiated. So, > it is better to negotiate nothing by default. But it is always > painful to change defaults. You need to explain that now you > need to negotiate Rx metadata to use mark, flag and tunnel offloads. > Yes, it will be required on sfc and cnxk only. > As an sfc maintainer I don't mind to change testpmd defaults. If we change testpmd defaults to "do nothing", then we should disable MBUF_FAST_FREE as well.
