Re: [PATCH 1/1] test/pmd_perf: handling of unknown connection speed

[Thomas Monjalon <thomas@monjalon.net>]

27/06/2022 09:18, Heinrich Schuchardt:
> On 6/26/22 17:15, Thomas Monjalon wrote:
> > 11/05/2022 18:33, Heinrich Schuchardt:
> >> When running DPDK in QEMU it cannot determine the connection speed.
> >> pmd_perf_autotest treats this as if the connection speed where
> >> UNIT32_MAX Mbps:
> >>
> >>      RTE>>pmd_perf_autotest
> >>      Start PMD RXTX cycles cost test.
> >>      Allocated mbuf pool on socket 0
> >>      CONFIG RXD=1024 TXD=1024
> >>      Performance test runs on lcore 1 socket 0
> >>      Port 0 Address:52:54:00:12:34:57
> >>      Port 1 Address:52:54:00:12:34:58
> >>      Checking link statuses...
> >>      Port 0 Link up at Unknown FDX Autoneg
> >>      Port 1 Link up at Unknown FDX Autoneg
> >>      IPv4 pktlen 46
> >>      UDP pktlen 26
> >>      Generate 4096 packets @socket 0
> >>      inject 2048 packet to port 0
> >>      inject 2048 packet to port 1
> >>      Total packets inject to prime ports = 4096
> >>      Each port will do 6391320379464 packets per second
> >>      Test will stop after at least 25565281517856 packets received
> >>
> >> This will not allow the test to terminate in a reasonable timespan.
> >> Just assume 10 Gbps in this case instead:
> >>
> >>      ...
> >>      Test will stop after at least 59523808 packets received
> >>
> >> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> >> ---
> >>   app/test/test_pmd_perf.c | 15 +++++++++++----
> >>   1 file changed, 11 insertions(+), 4 deletions(-)
> >>
> >> diff --git a/app/test/test_pmd_perf.c b/app/test/test_pmd_perf.c
> >> index 25611bfe9b..ee08c8aade 100644
> >> --- a/app/test/test_pmd_perf.c
> >> +++ b/app/test/test_pmd_perf.c
> >> @@ -486,10 +486,17 @@ main_loop(__rte_unused void *args)
> >>   	}
> >>   	printf("Total packets inject to prime ports = %u\n", idx);
> >>   
> >> -	packets_per_second = (link_mbps * 1000 * 1000) /
> >> -		((PACKET_SIZE + FRAME_GAP + MAC_PREAMBLE) * CHAR_BIT);
> >> -	printf("Each port will do %"PRIu64" packets per second\n",
> >> -	       packets_per_second);
> >> +	if (link_mbps != RTE_ETH_SPEED_NUM_UNKNOWN) {
> >> +		packets_per_second = (link_mbps * 1000 * 1000) /
> >> +			((PACKET_SIZE + FRAME_GAP + MAC_PREAMBLE) * CHAR_BIT);
> >> +		printf("Each port will do %"PRIu64" packets per second\n",
> >> +		       packets_per_second);
> >> +		total_packets = RTE_TEST_DURATION * conf->nb_ports * packets_per_second;
> 
> Yes this line should be removed.
> 
> > 
> > This is redundant with below.
> > 
> >> +	} else {
> >> +		/* We don't know the speed. Pretend it is 10G */
> >> +		packets_per_second = ((uint64_t)RTE_ETH_SPEED_NUM_10G * 1000 * 1000) /
> >> +			((PACKET_SIZE + FRAME_GAP + MAC_PREAMBLE) * CHAR_BIT);
> >> +	}
> >>   
> >>   	total_packets = RTE_TEST_DURATION * conf->nb_ports * packets_per_second;
> > 
> > Why not just inserting this:
> > 
> > if (link_mbps == RTE_ETH_SPEED_NUM_UNKNOWN)
> > 	link_mbps = RTE_ETH_SPEED_NUM_10G;
> 
> Following your suggestion the message "Each port will do %"PRIu64" 
> packets per second\n" would provide misleading information to the user. 
> This should be avoided.

OK so we can have the printf inside an "if condition":

bool speed_unknown = (link_mbps == RTE_ETH_SPEED_NUM_UNKNOWN);
if (speed_unknown)
	link_mbps = RTE_ETH_SPEED_NUM_10G;
packets_per_second = ...;
if (!speed_unknown)
	printf(...);
total_packets = ...;