[dpdk-dev] [PATCH 0/9] mbuf: structure reorganization

[Bruce Richardson]

On Tue, Apr 04, 2017 at 09:58:49AM +0200, Olivier MATZ wrote:
> On Mon, 03 Apr 2017 18:15:25 +0200
> Thomas Monjalon <thomas.monjalon at 6wind.com> wrote:
> 
> > 2017-03-31 09:18, Ananyev, Konstantin:
> > > > On Fri, 31 Mar 2017 09:41:39 +0100, Bruce Richardson
> > > > <bruce.richardson at intel.com> wrote:  
> > > > > On Fri, Mar 31, 2017 at 10:26:10AM +0200, Olivier Matz wrote:  
> > > > > > I replayed my tests, and I can also see a performance loss
> > > > > > with 1c/1t (ixgbe), not in the same magnitude however. Here
> > > > > > is what I have in MPPS:
> > > > > >
> > > > > > 1c/1t   1c/2t
> > > > > > 53.3    58.7     current
> > > > > > 52.1    58.8     original patchset
> > > > > > 53.3    58.8     removed patches 3 and 9
> > > > > > 53.1    58.7     with konstantin's patch
> > > > > >
> > > > > > So we have 2 options here:
> > > > > >
> > > > > > 1/ integrate Konstantin's patch in the patchset (thank you,
> > > > > > by the way) 2/ remove patch 3, and keep it for later until we
> > > > > > have something that really no impact
> > > > > >
> > > > > > I'd prefer 1/, knowing that the difference is really small in
> > > > > > terms of cycles per packet.
> > > > > >
> > > > > >  
> > > > > 1 is certainly the more attractive option. However, I think we
> > > > > can afford to spend a little more time looking at this before
> > > > > we decide. I'll try and check out the perf numbers I get with
> > > > > i40e with Konstantin's patch today. We also need to double
> > > > > check the other possible issues he reported in his other
> > > > > emails. While I don't want this patchset held up for a long
> > > > > time, I think an extra 24/48 hours is probably needed on it.
> > > > >  
> > > > 
> > > > Yes, now that we have the "test momentum", try not to loose it ;)
> > > > 
> > > > I'm guilty to have missed the performance loss, but honnestly,
> > > > I'm a bit sad that nobody tried to this patchset before (it
> > > > is available for more than 2 months), knowing this is probably
> > > > one of the most critical part of dpdk. I think we need to be
> > > > better next time.
> > > > 
> > > > Anyway, thank you for your test and feedback now.  
> > > 
> > > I am also leaning towards option 1, but agree that some extra
> > > testing first need to be done before making the final decision.
> > > BTW, path #9 need to be removed anyway, even if will go for path #1.
> > > Konstantin  
> > 
> > Please, can we have a conclusion now?
> 
> I think we sholuld go with proposition 1, I can resubmit an updated
> patch today.
> 
> This rework is needed at least for metrics libraries.
> 
> To summarize the perf data we have:
> - There is a small impact on Intel NICs (-0.4MPPS on ixgbe in iofwd
>   mode according to Konstantin's test, which is less than 1%). I guess
>   it can be optimized.
> - On mlx5, there is a gain (+0.8MPPS).
> - On sfc, there is also a gain.
> 
> Any comment?
> 
> Olivier

Hi,

As you have probably seen from the patches I sent yesterday, there are
optimizations we can make to our i40e (and ixgbe) drivers on top of this
patchset which should compensate for any performance loss due to the
mbuf rework. Therefore, we are ok to have this merged, so long as our
PMD enhancements based on this set can also be merged (they are not
large, so I assume this should not be controvertial). The i40e patches
are on the list; an equivalent set for ixgbe should be submitted by
Konstantin shortly.

Regards,
/Bruce