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Date: Thu, 14 Oct 2010 13:28:58 +0530 From: Krishna Kumar2 <krkumar2@...ibm.com> To: "Michael S. Tsirkin" <mst@...hat.com> Cc: anthony@...emonkey.ws, arnd@...db.de, avi@...hat.com, davem@...emloft.net, kvm@...r.kernel.org, netdev@...r.kernel.org, rusty@...tcorp.com.au Subject: Re: [v2 RFC PATCH 0/4] Implement multiqueue virtio-net "Michael S. Tsirkin" <mst@...hat.com> wrote on 10/12/2010 10:39:07 PM: > > Sorry for the delay, I was sick last couple of days. The results > > with your patch are (%'s over original code): > > > > Code BW% CPU% RemoteCPU > > MQ (#txq=16) 31.4% 38.42% 6.41% > > MQ+MST (#txq=16) 28.3% 18.9% -10.77% > > > > The patch helps CPU utilization but didn't help single stream > > drop. > > > > Thanks, > > What other shared TX/RX locks are there? In your setup, is the same > macvtap socket structure used for RX and TX? If yes this will create > cacheline bounces as sk_wmem_alloc/sk_rmem_alloc share a cache line, > there might also be contention on the lock in sk_sleep waitqueue. > Anything else? The patch is not introducing any locking (both vhost and virtio-net). The single stream drop is due to different vhost threads handling the RX/TX traffic. I added a heuristic (fuzzy) to determine if more than one flow is being used on the device, and if not, use vhost[0] for both tx and rx (vhost_poll_queue figures this out before waking up the suitable vhost thread). Testing shows that single stream performance is as good as the original code. __________________________________________________________________________ #txqs = 2 (#vhosts = 3) # BW1 BW2 (%) CPU1 CPU2 (%) RCPU1 RCPU2 (%) __________________________________________________________________________ 1 77344 74973 (-3.06) 172 143 (-16.86) 358 324 (-9.49) 2 20924 21107 (.87) 107 103 (-3.73) 220 217 (-1.36) 4 21629 32911 (52.16) 214 391 (82.71) 446 616 (38.11) 8 21678 34359 (58.49) 428 845 (97.42) 892 1286 (44.17) 16 22046 34401 (56.04) 841 1677 (99.40) 1785 2585 (44.81) 24 22396 35117 (56.80) 1272 2447 (92.37) 2667 3863 (44.84) 32 22750 35158 (54.54) 1719 3233 (88.07) 3569 5143 (44.10) 40 23041 35345 (53.40) 2219 3970 (78.90) 4478 6410 (43.14) 48 23209 35219 (51.74) 2707 4685 (73.06) 5386 7684 (42.66) 64 23215 35209 (51.66) 3639 6195 (70.23) 7206 10218 (41.79) 80 23443 35179 (50.06) 4633 7625 (64.58) 9051 12745 (40.81) 96 24006 36108 (50.41) 5635 9096 (61.41) 10864 15283 (40.67) 128 23601 35744 (51.45) 7475 12104 (61.92) 14495 20405 (40.77) __________________________________________________________________________ SUM: BW: (37.6) CPU: (69.0) RCPU: (41.2) __________________________________________________________________________ #txqs = 8 (#vhosts = 5) # BW1 BW2 (%) CPU1 CPU2 (%) RCPU1 RCPU2 (%) __________________________________________________________________________ 1 77344 75341 (-2.58) 172 171 (-.58) 358 356 (-.55) 2 20924 26872 (28.42) 107 135 (26.16) 220 262 (19.09) 4 21629 33594 (55.31) 214 394 (84.11) 446 615 (37.89) 8 21678 39714 (83.19) 428 949 (121.72) 892 1358 (52.24) 16 22046 39879 (80.88) 841 1791 (112.96) 1785 2737 (53.33) 24 22396 38436 (71.61) 1272 2111 (65.95) 2667 3453 (29.47) 32 22750 38776 (70.44) 1719 3594 (109.07) 3569 5421 (51.89) 40 23041 38023 (65.02) 2219 4358 (96.39) 4478 6507 (45.31) 48 23209 33811 (45.68) 2707 4047 (49.50) 5386 6222 (15.52) 64 23215 30212 (30.13) 3639 3858 (6.01) 7206 5819 (-19.24) 80 23443 34497 (47.15) 4633 7214 (55.70) 9051 10776 (19.05) 96 24006 30990 (29.09) 5635 5731 (1.70) 10864 8799 (-19.00) 128 23601 29413 (24.62) 7475 7804 (4.40) 14495 11638 (-19.71) __________________________________________________________________________ SUM: BW: (40.1) CPU: (35.7) RCPU: (4.1) _______________________________________________________________________________ The SD numbers are also good (same table as before, but SD instead of CPU: __________________________________________________________________________ #txqs = 2 (#vhosts = 3) # BW% SD1 SD2 (%) RSD1 RSD2 (%) __________________________________________________________________________ 1 -3.06) 5 4 (-20.00) 21 19 (-9.52) 2 .87 6 6 (0) 27 27 (0) 4 52.16 26 32 (23.07) 108 103 (-4.62) 8 58.49 103 146 (41.74) 431 445 (3.24) 16 56.04 407 514 (26.28) 1729 1586 (-8.27) 24 56.80 934 1161 (24.30) 3916 3665 (-6.40) 32 54.54 1668 2160 (29.49) 6925 6872 (-.76) 40 53.40 2655 3317 (24.93) 10712 10707 (-.04) 48 51.74 3920 4486 (14.43) 15598 14715 (-5.66) 64 51.66 7096 8250 (16.26) 28099 27211 (-3.16) 80 50.06 11240 12586 (11.97) 43913 42070 (-4.19) 96 50.41 16342 16976 (3.87) 63017 57048 (-9.47) 128 51.45 29254 32069 (9.62) 113451 108113 (-4.70) __________________________________________________________________________ SUM: BW: (37.6) SD: (10.9) RSD: (-5.3) __________________________________________________________________________ #txqs = 8 (#vhosts = 5) # BW% SD1 SD2 (%) RSD1 RSD2 (%) __________________________________________________________________________ 1 -2.58 5 5 (0) 21 21 (0) 2 28.42 6 6 (0) 27 25 (-7.40) 4 55.31 26 32 (23.07) 108 102 (-5.55) 8 83.19 103 128 (24.27) 431 368 (-14.61) 16 80.88 407 593 (45.70) 1729 1814 (4.91) 24 71.61 934 965 (3.31) 3916 3156 (-19.40) 32 70.44 1668 3232 (93.76) 6925 9752 (40.82) 40 65.02 2655 5134 (93.37) 10712 15340 (43.20) 48 45.68 3920 4592 (17.14) 15598 14122 (-9.46) 64 30.13 7096 3928 (-44.64) 28099 11880 (-57.72) 80 47.15 11240 18389 (63.60) 43913 55154 (25.59) 96 29.09 16342 21695 (32.75) 63017 66892 (6.14) 128 24.62 29254 36371 (24.32) 113451 109219 (-3.73) __________________________________________________________________________ SUM: BW: (40.1) SD: (29.0) RSD: (0) This approach works nicely for both single and multiple stream. Does this look good? Thanks, - KK -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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