On Tue, Jun 06, 2017 at 10:59:59AM +0100, Ananyev, Konstantin wrote: > > > > > > > > > > > > > > > > > > The PROD/CONS_ALIGN values on x86-64 are set to 2 cache lines, so > > > > members > > > of struct rte_ring are 128 byte aligned, > > > >and therefore the whole struct needs 128-byte alignment according to the > > > >ABI > > > so that the 128-byte alignment of the fields can be guaranteed. > > > > > > Ah ok, missed the fact that rte_ring is 128B aligned these days. > > > BTW, I probably missed the initial discussion, but what was the reason > > > for that? > > > Konstantin > > > > I don't know why PROD_ALIGN/CONS_ALIGN use 128 byte alignment; it seems > > unnecessary if the cache line is only 64 bytes. An alternate > > fix would be to just use cache line alignment for these fields (since > > memzones are already cache line aligned). > > Yes, had the same thought. > > > Maybe there is some deeper reason for the >= 128-byte alignment logic in > > rte_ring.h? > > Might be, would be good to hear opinion the author of that change.
It gives improved performance for core-2-core transfer. /Bruce
