On Fri, 31 Mar 2017 09:41:39 +0100, Bruce Richardson <bruce.richard...@intel.com> wrote: > On Fri, Mar 31, 2017 at 10:26:10AM +0200, Olivier Matz wrote: > > Hi, > > > > On Fri, 31 Mar 2017 01:00:49 +0000, "Ananyev, Konstantin" > > <konstantin.anan...@intel.com> wrote: > > > > > > > > > > > > > > > > > > > > > -----Original Message----- > > > > > > From: Richardson, Bruce > > > > > > Sent: Thursday, March 30, 2017 1:23 PM > > > > > > To: Olivier Matz <olivier.m...@6wind.com> > > > > > > Cc: dev@dpdk.org; Ananyev, Konstantin > > > > > > <konstantin.anan...@intel.com>; m...@smartsharesystems.com; > > > > > > Chilikin, Andrey > > > > > > <andrey.chili...@intel.com>; jblu...@infradead.org; > > > > > > nelio.laranje...@6wind.com; arybche...@solarflare.com > > > > > > Subject: Re: [dpdk-dev] [PATCH 0/9] mbuf: structure reorganization > > > > > > > > > > > > On Thu, Mar 30, 2017 at 02:02:36PM +0200, Olivier Matz wrote: > > > > > > > On Thu, 30 Mar 2017 10:31:08 +0100, Bruce Richardson > > > > > > > <bruce.richard...@intel.com> wrote: > > > > > > > > On Wed, Mar 29, 2017 at 09:09:23PM +0100, Bruce Richardson > > > > > > > > wrote: > > > > > > > > > On Wed, Mar 29, 2017 at 05:56:29PM +0200, Olivier Matz wrote: > > > > > > > > > > > > > > > > > > > Hi, > > > > > > > > > > > > > > > > > > > > Does anyone have any other comment on this series? > > > > > > > > > > Can it be applied? > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > Thanks, > > > > > > > > > > Olivier > > > > > > > > > > > > > > > > > > > > > > > > > > > > I assume all driver maintainers have done performance > > > > > > > > > analysis to check > > > > > > > > > for regressions. Perhaps they can confirm this is the case. > > > > > > > > > > > > > > > > > > /Bruce > > > > > > > > > > > > > > > > > > In the absence, of anyone else reporting performance numbers > > > > > > > > with this > > > > > > > > patchset, I ran a single-thread testpmd test using 2 x 40G > > > > > > > > ports (i40e) > > > > > > > > driver. With RX & TX descriptor ring sizes of 512 or above, I'm > > > > > > > > seeing a > > > > > > > > fairly noticable performance drop. I still need to dig in more, > > > > > > > > e.g. do > > > > > > > > an RFC2544 zero-loss test, and also bisect the patchset to see > > > > > > > > what > > > > > > > > parts may be causing the problem. > > > > > > > > > > > > > > > > Has anyone else tried any other drivers or systems to see what > > > > > > > > the perf > > > > > > > > impact of this set may be? > > > > > > > > > > > > > > I did, of course. I didn't see any noticeable performance drop on > > > > > > > ixgbe (4 NICs, one port per NIC, 1 core). I can replay the test > > > > > > > with > > > > > > > current version. > > > > > > > > > > > > > I had no doubt you did some perf testing! :-) > > > > > > > > > > > > Perhaps the regression I see is limited to i40e driver. I've > > > > > > confirmed I > > > > > > still see it with that driver in zero-loss tests, so next step is > > > > > > to try > > > > > > and localise what change in the patchset is causing it. > > > > > > > > > > > > Ideally, though, I think we should see acks or other comments from > > > > > > driver maintainers at least confirming that they have tested. You > > > > > > cannot > > > > > > be held responsible for testing every DPDK driver before you submit > > > > > > work > > > > > > like this. > > > > > > > > > > > > > > > > Unfortunately I also see a regression. > > > > > Did a quick flood test on 2.8 GHZ IVB with 4x10Gb. > > > > > > > > Sorry, forgot to mention - it is on ixgbe. > > > > So it doesn't look like i40e specific. > > > > > > > > > Observed a drop even with default testpmd RXD/TXD numbers (128/512): > > > > > from 50.8 Mpps down to 47.8 Mpps. > > > > > From what I am seeing the particular patch that causing it: > > > > > [dpdk-dev,3/9] mbuf: set mbuf fields while in pool > > > > > > > > > > cc version 5.3.1 20160406 (Red Hat 5.3.1-6) (GCC) > > > > > cmdline: > > > > > ./dpdk.org-1705-mbuf1/x86_64-native-linuxapp-gcc/app/testpmd > > > > > --lcores='7,8' -n 4 --socket-mem='1024,0' -w 04:00.1 -w 07:00.1 -w > > > > > 0b:00.1 -w 0e:00.1 -- -i > > > > > > > > > > > After applying the patch below got nearly original numbers (though not > > > quite) on my box. > > > dpdk.org mainline: 50.8 > > > with Olivier patch: 47.8 > > > with patch below: 50.4 > > > What I tried to do in it - avoid unnecessary updates of mbuf inside > > > rte_pktmbuf_prefree_seg(). > > > For one segment per packet it seems to help. > > > Though so far I didn't try it on i40e and didn't do any testing for > > > multi-seg scenario. > > > Konstantin > > > > 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. Olivier
