Re: [dpdk-dev] [dpdk-stable] [PATCH] test/pmd_perf: change the way to drain the port

["Meunier, Julien (Nokia - FR/Paris-Saclay)" <julien.meunier@nokia.com>]

Hi,

Inline reply,

On 08/01/2019 18:33, Ferruh Yigit wrote:
> On 1/2/2019 3:55 PM, Julien Meunier wrote:
>> If the port has received less than ``pkt_per_port`` packets (for
>> example, the port has missed some packets), the test is in an infinite
>> loop.
>>
>> Instead of expecting a number of packet to receive, let the port to be
>> drained by itself. If no more packets are received, the test can
>> continue.
> 
> This looks like fixing the test_pmd_perf test case, which can stuck into endless
> loop without this patch, and since there will be already a new version for below
> comment, can you please update the patch title to describe the fix, like
> 
> test/pmd_perf: fix ....

Sure ! I will be more careful next time with the title of my patches

>>
>> Fixes: 002ade70e933 ("app/test: measure cycles per packet in Rx/Tx")
>> Cc: stable@dpdk.org
>>
>> Signed-off-by: Julien Meunier <julien.meunier@nokia.com>
>> ---
>>   test/test/test_pmd_perf.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/test/test/test_pmd_perf.c b/test/test/test_pmd_perf.c
>> index f5095c8..286e09d 100644
>> --- a/test/test/test_pmd_perf.c
>> +++ b/test/test/test_pmd_perf.c
>> @@ -493,15 +493,15 @@ main_loop(__rte_unused void *args)
>>   
>>   	for (i = 0; i < conf->nb_ports; i++) {
>>   		portid = conf->portlist[i];
>> -		int nb_free = pkt_per_port;
>> +		int nb_free = 0;
> 
> 'nb_free' is not more used or required, it can be removed completely I think.

Damn.. Missing one little correction: nb_free should be used in the printf.

- printf("free %d mbuf left in port %u\n", pkt_per_port, portid);
+ printf("free %d mbuf left in port %u\n", nb_free, portid);

> 
>>   		do { /* dry out */
>>   			nb_rx = rte_eth_rx_burst(portid, 0,
>>   						 pkts_burst, MAX_PKT_BURST);
>>   			nb_tx = 0;
>>   			while (nb_tx < nb_rx)
>>   				rte_pktmbuf_free(pkts_burst[nb_tx++]);
>> -			nb_free -= nb_rx;
>> -		} while (nb_free != 0);
>> +			nb_free += nb_rx;
>> +		} while (nb_rx != 0);
> 
> Isn't there already something wrong with this logic? It assumes after test done
> device still has 'pkt_per_port' packets in its queues, it tries to receive and
> free them, but:
> 
> nb_free = pkt_per_port = MAX_TRAFFIC_BURST = 2048
> RTE_TEST_RX_DESC_DEFAULT = RTE_TEST_TX_DESC_DEFAULT = 1024

All ports are configured with the following number of descriptors:
nb_rxd = MAX_TRAFFIC_BURST;
nb_txd = MAX_TRAFFIC_BURST;

In this case, all is OK.

But, for the test SC_CONTINUOUS (which is, by the way, the default one), 
this number is reduced
nb_rxd = RTE_TEST_RX_DESC_DEFAULT ;
nb_txd = RTE_TEST_TX_DESC_DEFAULT ;

> When device queue length is 1024, how it can be holding 2048 packets? So it
> can't exit from this loop. Since this should be working, what am I missing?

In the main_loop, the test xmits 2048 pkts per port. Then, do_measure 
-measure_rxtx for example- receives all incoming packets and resends to 
the port.

However... Without my patch, on a previous DPDK version (17.08), which 
configures less RX and TX descriptors (RXD=128 TXD=512), I didn't notice 
this issue on ixgbe PMD (but not on fm10k).

So... You're right, how it can be holding 2048 packets with this 
configuration... I will check on my side.

> But overall, this stage is after the test done and for cleanup, I think your
> suggestion is reasonable, only please check above 'nb_free' comment.

I will submit a new patch.

Thanks for your comments !

> Thanks,
> ferruh
> 

Best regards,
Julien Meunier