Thread (54 messages) 54 messages, 4 authors, 2016-06-28

Re: [PATCH v3 4/5] testpmd: handle all rxqs in rss setup

From: Nélio Laranjeiro <hidden>
Date: 2016-06-27 14:23:44

On Tue, Jun 14, 2016 at 07:08:05PM -0400, Zhihong Wang wrote:
quoted hunk ↗ jump to hunk
This patch removes constraints in rxq handling when multiqueue is enabled
to handle all the rxqs.

Current testpmd forces a dedicated core for each rxq, some rxqs may be
ignored when core number is less than rxq number, and that causes confusion
and inconvenience.

One example: One Red Hat engineer was doing multiqueue test, there're 2
ports in guest each with 4 queues, and testpmd was used as the forwarding
engine in guest, as usual he used 1 core for forwarding, as a results he
only saw traffic from port 0 queue 0 to port 1 queue 0, then a lot of
emails and quite some time are spent to root cause it, and of course it's
caused by this unreasonable testpmd behavior.  

Moreover, even if we understand this behavior, if we want to test the
above case, we still need 8 cores for a single guest to poll all the
rxqs, obviously this is too expensive.

We met quite a lot cases like this, one recent example:
http://openvswitch.org/pipermail/dev/2016-June/072110.html


Signed-off-by: Zhihong Wang <redacted>
---
 app/test-pmd/config.c | 8 +-------
 1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/app/test-pmd/config.c b/app/test-pmd/config.c
index ede7c78..4719a08 100644
--- a/app/test-pmd/config.c
+++ b/app/test-pmd/config.c
@@ -1199,19 +1199,13 @@ rss_fwd_config_setup(void)
 	cur_fwd_config.nb_fwd_ports = nb_fwd_ports;
 	cur_fwd_config.nb_fwd_streams =
 		(streamid_t) (nb_q * cur_fwd_config.nb_fwd_ports);
-	if (cur_fwd_config.nb_fwd_streams > cur_fwd_config.nb_fwd_lcores)
-		cur_fwd_config.nb_fwd_streams =
-			(streamid_t)cur_fwd_config.nb_fwd_lcores;
-	else
-		cur_fwd_config.nb_fwd_lcores =
-			(lcoreid_t)cur_fwd_config.nb_fwd_streams;
 
 	/* reinitialize forwarding streams */
 	init_fwd_streams();
 
 	setup_fwd_config_of_each_lcore(&cur_fwd_config);
 	rxp = 0; rxq = 0;
-	for (lc_id = 0; lc_id < cur_fwd_config.nb_fwd_lcores; lc_id++) {
+	for (lc_id = 0; lc_id < cur_fwd_config.nb_fwd_streams; lc_id++) {
 		struct fwd_stream *fs;
 
 		fs = fwd_streams[lc_id];
-- 
2.5.0
Hi Zhihong,

It seems this commits introduce a bug in pkt_burst_transmit(), this only
occurs when the number of cores present in the coremask is greater than
the number of queues i.e. coremask=0xffe --txq=4 --rxq=4.

  Port 0 Link Up - speed 40000 Mbps - full-duplex
  Port 1 Link Up - speed 40000 Mbps - full-duplex
  Done
  testpmd> start tx_first
    io packet forwarding - CRC stripping disabled - packets/burst=64
    nb forwarding cores=10 - nb forwarding ports=2
    RX queues=4 - RX desc=256 - RX free threshold=0
    RX threshold registers: pthresh=0 hthresh=0 wthresh=0
    TX queues=4 - TX desc=256 - TX free threshold=0
    TX threshold registers: pthresh=0 hthresh=0 wthresh=0
    TX RS bit threshold=0 - TXQ flags=0x0
  Segmentation fault (core dumped)


If I start testpmd with a coremask with at most as many cores as queues,
everything works well (i.e. coremask=0xff0, or 0xf00).

Are you able to reproduce the same issue?
Note: It only occurs on dpdk/master branch (commit f2bb7ae1d204).

Regards,

-- 
Nélio Laranjeiro
6WIND
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