-----Original Message----- > Date: Mon, 12 Feb 2018 13:44:54 +0000 > From: Matan Azrad <ma...@mellanox.com> > To: Jerin Jacob <jerin.ja...@caviumnetworks.com>, "dev@dpdk.org" > <dev@dpdk.org> > CC: "ferruh.yi...@intel.com" <ferruh.yi...@intel.com>, "sta...@dpdk.org" > <sta...@dpdk.org>, Thomas Monjalon <tho...@monjalon.net>, Konstantin > Ananyev <konstantin.anan...@intel.com>, Pavan Nikhilesh > <pbhagavat...@caviumnetworks.com> > Subject: RE: [dpdk-dev] [PATCH v3] ethdev: fix ethdev data alignment > > Hi Jerin > > From: Jerin Jacob [mailto:jerin.ja...@caviumnetworks.com] > > The struct rte_eth_dev_data is used in ethdev fastpath routines and it not > > aligned to cache line size. This patch fixes the ethdev data alignment. > > > > The alignment was broken from the "first public release" changeset where > > ethdev data address was aligned only to the first port. > > Remaining ports alignment was defined by the size of the struct > > (rte_eth_dev_data). This scheme is not guaranteed to be cache line aligned > > all the time. > > > > "ethdev: add port ownership" change set introduced a > > rte_eth_dev_shared_data container for port ownership change, This > > resulted in rte_eth_dev->data memory for the first port also as cache > > unaligned. > > > > Added a compiler alignment attribute to make sure rte_eth_dev->data > > always cache aligned so that CPU/compiler > > 1) Avoid sharing the element with another cache line > > 2) Can load/store the elements in struct rte_eth_dev_data as naturally > > aligned. > > > > Some platform like thunderX could see performance regression of 1% at > > "ethdev: add port ownership" change set with > > 1 port/1 queue l3fwd application and this patch fixes that regression. > > > > example command: > > sudo ./examples/l3fwd/build/l3fwd -c 0xff00 -- -p 0x1 --config="(0,0,9)" > > > > Fixes: af75078fece3 ("first public release") > > Fixes: 5b7ba31148a8 ("ethdev: add port ownership") > > I don't think you need the add the 5b7ba31148a8 fix line. > Maybe think about it in the next way: > Is your fix can stay as a same fix before the port ownership feature addition? > If yes, You are not fixing it.
I don't think so. 5b7ba31148a8 breaking the first port alignment case(as mentioned in the commit log clearly). First port alignment was correct prior to 5b7ba31148a8 change set Do you agree? > > I think that the port ownership just exposed the issue, did not initiated it. > > > Cc: sta...@dpdk.org > > > > Cc: Matan Azrad <ma...@mellanox.com> > > Cc: Thomas Monjalon <tho...@monjalon.net> > > Cc: Konstantin Ananyev <konstantin.anan...@intel.com> > > > > Signed-off-by: Jerin Jacob <jerin.ja...@caviumnetworks.com> > > Signed-off-by: Pavan Nikhilesh <pbhagavat...@caviumnetworks.com> > > --- > > > > v3: > > - added more history/data in the git log > > - added sta...@dpdk.org in Cc > > > > v2: > > - Change the git comments based on Matan's feedback > > https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdpd > > k.org%2Fdev%2Fpatchwork%2Fpatch%2F35104%2F&data=02%7C01%7Cmata > > n%40mellanox.com%7Cd491698ead5f48626c1408d5721a8331%7C8c5c71989d > > be4cf9a2099e499881116c%7C0%7C0%7C636540380570748030&sdata=if8cCrk3 > > U0XqWp8NE%2BEP1BjuPHX95HHN0f1yjk6krV0%3D&reserved=0 > > > > --- > > lib/librte_ether/rte_ethdev_core.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/lib/librte_ether/rte_ethdev_core.h > > b/lib/librte_ether/rte_ethdev_core.h > > index 315b31723..e5681e466 100644 > > --- a/lib/librte_ether/rte_ethdev_core.h > > +++ b/lib/librte_ether/rte_ethdev_core.h > > @@ -601,7 +601,7 @@ struct rte_eth_dev_data { > > struct rte_vlan_filter_conf vlan_filter_conf; > > /**< VLAN filter configuration. */ > > struct rte_eth_dev_owner owner; /**< The port owner. */ -}; > > +} __rte_cache_aligned; > > > > /** > > * @internal > > -- > > 2.16.1 >
