debloat-testing loadlatency test

[Jonathan Morton]

On 21 Mar, 2011, at 9:43 pm, Jonathan Morton wrote:

> I'd like to establish that high smoothness and responsiveness figures are actually possible.

And here is the beginning of that proof: a run between my MBP and my firewall (an old PowerBook G3 running Linux) over Ethernet.  The G3 only supports 100base-TX, but has SFQ turned on for that port, and is using my Blackpool mod (designed for 3G) in it's TCP stack.  The MBP is stock Snow Leopard fare.

MinRTT: 0.0ms
Scenario 1: 0 uploads, 1 downloads... 11486 KiB/s down, 30.19 Hz smoothness
Scenario 2: 1 uploads, 0 downloads... 11439 KiB/s up, 68.72 Hz smoothness
Scenario 3: 0 uploads, 2 downloads... 11506 KiB/s down, 28.20 Hz smoothness
Scenario 4: 1 uploads, 1 downloads... 11293 KiB/s up, 5024 KiB/s down, 26.74 Hz smoothness
Scenario 5: 2 uploads, 0 downloads... 11474 KiB/s up, 37.20 Hz smoothness
Scenario 6: 0 uploads, 3 downloads... 11514 KiB/s down, 20.26 Hz smoothness
Scenario 7: 1 uploads, 2 downloads... 10946 KiB/s up, 7253 KiB/s down, 20.76 Hz smoothness
Scenario 8: 2 uploads, 1 downloads... 11361 KiB/s up, 4428 KiB/s down, 21.33 Hz smoothness
Scenario 9: 3 uploads, 0 downloads... 11471 KiB/s up, 21.91 Hz smoothness
Scenario 10: 0 uploads, 4 downloads... 11515 KiB/s down, 19.66 Hz smoothness
Scenario 11: 1 uploads, 3 downloads... 9911 KiB/s up, 8196 KiB/s down, 23.96 Hz smoothness
Scenario 12: 2 uploads, 2 downloads... 11319 KiB/s up, 4705 KiB/s down, 9.80 Hz smoothness
Scenario 13: 3 uploads, 1 downloads... 11355 KiB/s up, 4230 KiB/s down, 19.53 Hz smoothness
Scenario 14: 4 uploads, 0 downloads... 11482 KiB/s up, 15.77 Hz smoothness
Scenario 15: 0 uploads, 32 downloads... 10673 KiB/s down, 0.68 Hz smoothness
Scenario 16: 1 uploads, 31 downloads... 1441 KiB/s up, 11462 KiB/s down, 1.97 Hz smoothness
Scenario 17: 16 uploads, 16 downloads... 11477 KiB/s up, 5043 KiB/s down, 2.48 Hz smoothness
Scenario 18: 31 uploads, 1 downloads... 11640 KiB/s up, 1561 KiB/s down, 0.48 Hz smoothness
Scenario 19: 32 uploads, 0 downloads... 11775 KiB/s up, 6.70 Hz smoothness

OVERALL:
    Upload Capacity: 7584 KiB/s
  Download Capacity: 5598 KiB/s
Link Responsiveness: 0 Hz
    Flow Smoothness: 0 Hz

The overall stats are still dragged down by poor 32-flow results, but notice that even with 32 uploads (towards the G3), the smoothness is considerably improved from the untweaked GigE situation.  For up to 4 flows, the smoothness remains high even with excellent link utilisation.

And this is with CUBIC being used on the G3, with nothing to trigger ECN.  That's probably the combination that drags down the 32-flow results.

 - Jonathan