> -----Original Message----- > From: Richardson, Bruce > Sent: Monday, June 15, 2015 5:23 PM > To: Ananyev, Konstantin > Cc: Olivier MATZ; dev at dpdk.org; Damjan Marion (damarion) > Subject: Re: [dpdk-dev] rte_mbuf.next in 2nd cacheline > > On Mon, Jun 15, 2015 at 05:10:44PM +0100, Ananyev, Konstantin wrote: > > > > > > > -----Original Message----- > > > From: Richardson, Bruce > > > Sent: Monday, June 15, 2015 5:02 PM > > > To: Ananyev, Konstantin > > > Cc: Olivier MATZ; dev at dpdk.org; Damjan Marion (damarion) > > > Subject: Re: [dpdk-dev] rte_mbuf.next in 2nd cacheline > > > > > > On Mon, Jun 15, 2015 at 04:59:55PM +0100, Ananyev, Konstantin wrote: > > > > > > > > > > > > > > > > As I can see, vector TX is the only one that calls > > > > __rte_pktmbuf_prefree_seg() directly. > > > > All others use rte_pktmbuf_free_seg(), that does ' m->next = NULL' > > > > anyway. > > > > For vector TX - yes, need to verify that it would not introduce a > > > > slowdown. > > > > Konstantin > > > > > > > > > > But if the function is only directly called from one place, and that > > > doesn't > > > have a problem, why would we bother making any change at all? > > > > > > For future usages? > > But sure, if you believe that we can safely remove 'm->next = NULL' at RX > > path, > > without any changes in the __rte_pktmbuf_prefree_seg() - > > that seems fine to me. > > Konstantin > > > > If we find it's not safe, we can add in the change to > __rte_pktmbuf_prefree_seg > as you suggest. > > One other question: based on this, do you think it's safe to also remove the > assignment to NULL from the pktmbuf_alloc function? I suspect it should be > safe, and > that should help any traffic-generator type applications that use that > function > extensively.
So it will be setup to NULL, either by: - mbuf constructor. - TX full-path free descriptors code. - upper layer code that uses 'next' pointer explicitly. ? I can't come-up with some breakage scenario off-hand. But that means that we have to should avoid resetting tx_offload in pktmbuf_alloc() too, right? Otherwise there probably wouldn't be any real gain. Konstantin > > /Bruce
