> On Wed, 15 Apr 2015 21:46:27 +0800 > Dong.Wang <dong.wang.pro at hotmail.com> wrote: > >> Yes, current implementation works well with IA, and the transmit packets >> function's rte_wmb() is also unneccessary. >> >> But there are two reasons for adding rte_wmb() in recv pkts function: >> 1) The memory barrier in recv pkts function and xmit pkts function are >> inconsistent, rte_wmb() should be added to recv pkts function or be >> removed from xmit pkts function. >> 2) DPDK will support PowerPC processor (Other developers are working on >> it), I check the memory ordering of PowerPC, there was no mention of >> store-store instruction's principle in MPC8544 Reference Manual, only >> said it is weak memory ordering. >> >> So, I think it is neccessary to add rte_wmb() to recv pkts function. >> >> Dong > > If PowerPC requires additional memory barriers then it should > introduce a new generic set of memory barrier macros that are no-ops > on other architectures. > > Please don't penalize x86 for places where other CPU's have > weaker consistency. >
Yes, put rte_wmb() here will penalize x86, I was inconsiderate of it. Maybe a new set of memory barrier macros will be introduced, it be discussed in another thread. For now, add rte_wmb() is unnessary, I'm waiting for new memory barrier macros. Dong
