> Subject: RE: [PATCH] netvsc: optimize stats counters performance > > > From: Stephen Hemminger [mailto:step...@networkplumber.org] > > Sent: Friday, 2 August 2024 19.33 > > > > On Fri, 2 Aug 2024 19:28:26 +0200 > > Morten Brørup <m...@smartsharesystems.com> wrote: > > > > > > > ea = rte_pktmbuf_mtod(m, const struct rte_ether_addr *); > > > > > - if (rte_is_multicast_ether_addr(ea)) { > > > > > - if (rte_is_broadcast_ether_addr(ea)) > > > > > - stats->broadcast++; > > > > > - else > > > > > - stats->multicast++; > > > > > - } > > > > > + RTE_BUILD_BUG_ON(offsetof(struct hn_stats, broadcast) != > > > > > + offsetof(struct hn_stats, multicast) + > > > > sizeof(uint64_t)); > > > > > + if (unlikely(rte_is_multicast_ether_addr(ea))) > > > > > + (&stats- > >multicast)[rte_is_broadcast_ether_addr(ea)]++; > > > > > } > > > > > > > > This makes the code a little harder to read. > > > > > > I agree it is somewhat convoluted. > > > It's a tradeoff... I preferred performance at the cost of making the code > > somewhat harder to read. > > > The RTE_BUILD_BUG_ON() also helps showing what is going on with the > weird > > indexing. > > Similar patches have been accepted by other drivers: > [virtio]: > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwor > k.dpdk.org%2Fproject%2Fdpdk%2Fpatch%2F20240801160312.205281-1- > mb%40smartsharesystems.com%2F&data=05%7C02%7Clongli%40microsoft.com > %7C014c845ad8ec4ea25fb508dcd8b22474%7C72f988bf86f141af91ab2d7cd011 > db47%7C1%7C0%7C638623506854135960%7CUnknown%7CTWFpbGZsb3d8eyJ > WIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0 > %7C%7C%7C&sdata=DrVP6TuTruREAxAoSEBED11TOapSqDN5stsDJJTuux0%3D&r > eserved=0 > [vhost-user]: > https://nam06.safelinks.protection.outlook.com/?url=https%3A%2F%2Fpatchwor > k.dpdk.org%2Fproject%2Fdpdk%2Fpatch%2F20240802143259.269827-1- > mb%40smartsharesystems.com%2F&data=05%7C02%7Clongli%40microsoft.com > %7C014c845ad8ec4ea25fb508dcd8b22474%7C72f988bf86f141af91ab2d7cd011 > db47%7C1%7C0%7C638623506854150865%7CUnknown%7CTWFpbGZsb3d8eyJ > WIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0 > %7C%7C%7C&sdata=85T9qnC4nbAwU53sxnfQ2lMayp5soX8BMEJsbB58ZBw%3D > &reserved=0 > > > > > Optimizing for multicast packets is not worth bothering. > > Optimizing for multicast/broadcast comes into play in multicast environments, > and during network broadcast storms. > Although I don't know if any of those two scenarios are relevant for this > specific > driver. > > > Keep the original code it is simpler. > > Let's keep similar code similar across drivers. > > @Long, @Wei, please Review/Ack, so the patch can be applied.
Reviewed-by: Long Li <lon...@microsoft.com>
