I had sent this mail to Michael last week - he agrees that I should
share this information on the list:
On latest net-next-2.6, virtio-net (guest->host) results are:
______________________________________________________________
SQ vs MQ (#txqs=8)
# BW1 BW2 (%) CPU1 CPU2 (%) RCPU1 RCPU2 (%)
_______________________________________________________________
1 105774 112256 (6.1) 257 255 (-.7) 532 549 (3.1)
2 20842 30674 (47.1) 107 150 (40.1) 208 279 (34.1)
4 22500 31953 (42.0) 241 409 (69.7) 467 619 (32.5)
8 22416 44507 (98.5) 477 1039 (117.8) 960 1459 (51.9)
16 22605 45372 (100.7) 905 2060 (127.6) 1895 2962 (56.3)
24 23192 44201 (90.5) 1360 3028 (122.6) 2833 4437 (56.6)
32 23158 43394 (87.3) 1811 3957 (118.4) 3770 5936 (57.4)
40 23322 42550 (82.4) 2276 4986 (119.0) 4711 7417 (57.4)
48 23564 41931 (77.9) 2757 5966 (116.3) 5653 8896 (57.3)
64 23949 41092 (71.5) 3788 7898 (108.5) 7609 11826 (55.4)
80 23256 41343 (77.7) 4597 9887 (115.0) 9503 14801 (55.7)
96 23310 40645 (74.3) 5588 11758 (110.4) 11381 17761 (56.0)
128 24095 41082 (70.5) 7587 15574 (105.2) 15029 23716 (57.8)
______________________________________________________________
Avg: BW: (58.3) CPU: (110.8) RCPU: (55.9)
It's true that average CPU% on guest is almost double that of the BW
improvement. But I don't think this is due to the patch (driver does no
synchronization, etc). To compare MQ vs SQ on a 10G card, I ran the
same test from host to remote host across cxgb3. The results are
somewhat similar:
(I changed cxgb_open on the client system to:
netif_set_real_num_tx_queues(dev, 1);
err = netif_set_real_num_rx_queues(dev, 1);
to simulate single queue (SQ))
_____________________________________
cxgb3 SQ vs cxgb3 MQ
# BW1 BW2 (%) CPU1 CPU2 (%)
_____________________________________
1 8301 8315 (.1) 5 4.66 (-6.6)
2 9395 9380 (-.1) 16 16 (0)
4 9411 9414 (0) 33 26 (-21.2)
8 9411 9398 (-.1) 60 62 (3.3)
16 9412 9413 (0) 116 117 (.8)
24 9442 9963 (5.5) 179 198 (10.6)
32 10031 10025 (0) 230 249 (8.2)
40 9953 10024 (.7) 300 312 (4.0)
48 10002 10015 (.1) 351 376 (7.1)
64 10022 10024 (0) 494 515 (4.2)
80 8894 10011 (12.5) 537 630 (17.3)
96 8465 9907 (17.0) 612 749 (22.3)
128 7541 9617 (27.5) 760 989 (30.1)
_____________________________________
Avg: BW: (3.8) CPU: (14.8)
(Each case runs runs once for 60 secs)
The BW increased modestly but CPU increased much more. I assume
the change I made above to convert the driver from MQ to SQ is not
incorrect.
Thanks,
- KK
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