[EXT] Re: [dpdk-stable] [PATCH v2] test: avoid hang if queues are full and Tx fails

[Thomas Monjalon]

29/11/2021 09:52, Rakesh Kudurumalla:
> From: Thomas Monjalon <thomas at monjalon.net>
> > 22/11/2021 08:59, Rakesh Kudurumalla:
> > > From: Thomas Monjalon <thomas at monjalon.net>
> > > > 20/07/2021 18:50, Rakesh Kudurumalla:
> > > > > Current pmd_perf_autotest() in continuous mode tries to enqueue
> > > > > MAX_TRAFFIC_BURST completely before starting the test. Some
> > > > > drivers cannot accept complete MAX_TRAFFIC_BURST even though
> > rx+tx
> > > > > desc
> > > > count
> > > > > can fit it.
> > > >
> > > > Which driver is failing to do so?
> > > > Why it cannot enqueue 32 packets?
> > >
> > > Octeontx2 driver is failing to enqueue because hardware buffers are full
> > before test.

Aren't you stopping the support of octeontx2?
Why do you care now?

> > 
> > Why hardware buffers are full?
> Hardware buffers are full because number of number of descriptors in continuous mode 
> Is less than MAX_TRAFFIC_BURST, so if enque fails , there is no way hardware can drop the
> Packets . pmd_per_autotest application evaluates performance after enqueueing packets
> Initially.
> > 
> > > pmd_perf_autotest() in continuous mode tries to enqueue
> > > MAX_TRAFFIC_BURST (2048) before starting the test.
> > >
> > > > > This patch changes behaviour to stop enqueuing after few retries.
> > > >
> > > > If there is a real limitation, there will be issues in more places
> > > > than this test program.
> > > > I feel it should be addressed either in the driver or at ethdev level.
> > > >
> > > > [...]
> > > > > @@ -480,10 +483,19 @@ main_loop(__rte_unused void *args)
> > > > >  			nb_tx = RTE_MIN(MAX_PKT_BURST, num);
> > > > >  			nb_tx = rte_eth_tx_burst(portid, 0,
> > > > >  						&tx_burst[idx], nb_tx);
> > > > > +			if (nb_tx == 0)
> > > > > +				retry_cnt++;
> > > > >  			num -= nb_tx;
> > > > >  			idx += nb_tx;
> > > > > +			if (retry_cnt == MAX_RETRY_COUNT) {
> > > > > +				retry_cnt = 0;
> > > > > +				break;
> > > > > +			}