On Tue, May 03, 2016 at 10:48:34AM +0100, De Lara Guarch, Pablo wrote: > > > > -----Original Message----- > > From: Richardson, Bruce > > Sent: Tuesday, May 03, 2016 10:45 AM > > To: Jerin Jacob > > Cc: dev at dpdk.org; De Lara Guarch, Pablo > > Subject: Re: [dpdk-dev] [PATCH] app/testpmd: add packet data prefetch in > > macswap loop > > > > On Mon, May 02, 2016 at 05:29:37PM +0530, Jerin Jacob wrote: > > > prefetch the next packet data address in advance in macswap loop > > > for performance improvement. > > > > > > Signed-off-by: Jerin Jacob <jerin.jacob at caviumnetworks.com> > > > --- > > > app/test-pmd/macswap.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/app/test-pmd/macswap.c b/app/test-pmd/macswap.c > > > index 154889d..c10f4b5 100644 > > > --- a/app/test-pmd/macswap.c > > > +++ b/app/test-pmd/macswap.c > > > @@ -113,6 +113,9 @@ pkt_burst_mac_swap(struct fwd_stream *fs) > > > if (txp->tx_ol_flags & TESTPMD_TX_OFFLOAD_INSERT_QINQ) > > > ol_flags |= PKT_TX_QINQ_PKT; > > > for (i = 0; i < nb_rx; i++) { > > > + if (likely(i < nb_rx - 1)) > > > + rte_prefetch0(rte_pktmbuf_mtod(pkts_burst[i + 1], > > > + void *)); > > > > At least on IA platforms, there is no issue with prefetching beyond the end > > of > > the array, since it's only a hint to the cpu. If this is true for other > > platforms, > > then I suggest we just drop the conditional and just always prefetch. > > That's what I thought when I saw this patch, but the problem is that the > prefetch is not for pkts_burst, > but for rte_pktmbuf_mtod(pkts_burst...), so there must be a limit in nb_rx - > 2, or there will be a seg fault. > > Pablo Good point, Pablo, I missed that subtlety here.
/Bruce > > > > /Bruce > > > > > mb = pkts_burst[i]; > > > eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *); > > > > > > -- > > > 2.1.0 > > >