Re: [dpdk-dev] [PATCH] app/testpmd: improve MAC swap performance

["Wiles, Keith" <keith.wiles@intel.com>]

> On Nov 23, 2018, at 4:43 PM, Wiles, Keith <keith.wiles@intel.com> wrote:
> 
> 
> 
>> On Nov 19, 2018, at 10:45 PM, Zhang, Qi Z <qi.z.zhang@intel.com> wrote:
>> 
>> The patch optimizes the mac swap operation by taking advantage
>> of SSE instructions, it only impacts x86 platform.
>> 
>> Cc: stable@dpdk.org
>> 
>> Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
>> ---
>> app/test-pmd/macswap.c | 16 +++++++++++++++-
>> 1 file changed, 15 insertions(+), 1 deletion(-)
>> 
>> diff --git a/app/test-pmd/macswap.c b/app/test-pmd/macswap.c
>> index a8384d5b8..0722782b0 100644
>> --- a/app/test-pmd/macswap.c
>> +++ b/app/test-pmd/macswap.c
>> @@ -78,7 +78,6 @@ pkt_burst_mac_swap(struct fwd_stream *fs)
>> 	struct rte_port  *txp;
>> 	struct rte_mbuf  *mb;
>> 	struct ether_hdr *eth_hdr;
>> -	struct ether_addr addr;
>> 	uint16_t nb_rx;
>> 	uint16_t nb_tx;
>> 	uint16_t i;
>> @@ -95,6 +94,15 @@ pkt_burst_mac_swap(struct fwd_stream *fs)
>> 	start_tsc = rte_rdtsc();
>> #endif
>> 
>> +#ifdef RTE_ARCH_X86
>> +	__m128i addr;
>> +	__m128i shfl_msk = _mm_set_epi8(15, 14, 13, 12,
>> +					5, 4, 3, 2,
>> +					1, 0, 11, 10,
>> +					9, 8, 7, 6);
> 
> I was playing around with these mask values and I was not able to make it work as I expected.
> I ended up with different values in the mask.
> 
> _mm_set_epi8(15, 14, 13, 12, 5, 4, 3, 2, 1, 0, 11, 10, 9, 8, 7, 6);
> 
> After dumping the memory for a large number of tests this one seems correct, can you verify your mask is correct?

Sorry, I do not know why I thought the code was not the same, but your example is correct my mistake.
> 
>> +#else
>> +	struct ether_addr addr;
>> +#endif
>> 	/*
>> 	 * Receive a burst of packets and forward them.
>> 	 */
>> @@ -123,9 +131,15 @@ pkt_burst_mac_swap(struct fwd_stream *fs)
>> 		eth_hdr = rte_pktmbuf_mtod(mb, struct ether_hdr *);
>> 
>> 		/* Swap dest and src mac addresses. */
>> +#ifdef RTE_ARCH_X86
>> +		addr = _mm_loadu_si128((__m128i *)eth_hdr);
>> +		addr = _mm_shuffle_epi8(addr, shfl_msk);
>> +		_mm_storeu_si128((__m128i *)eth_hdr, addr);
>> +#else
>> 		ether_addr_copy(&eth_hdr->d_addr, &addr);
>> 		ether_addr_copy(&eth_hdr->s_addr, &eth_hdr->d_addr);
>> 		ether_addr_copy(&addr, &eth_hdr->s_addr);
>> +#endif
>> 
>> 		mb->ol_flags &= IND_ATTACHED_MBUF | EXT_ATTACHED_MBUF;
>> 		mb->ol_flags |= ol_flags;
>> -- 
>> 2.13.6
>> 
> 
> Regards,
> Keith

Regards,
Keith