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Bug #713

closed

Shaper Wizard: When backlogged, high priority queues get zero bandwidth

Added by Aaron Berland over 14 years ago. Updated about 14 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
-
Category:
Traffic Shaper (ALTQ)
Target version:
2.0
Start date:
07/02/2010
Due date:
% Done:

100%

Estimated time:
Plus Target Version:
Release Notes:
Affected Version:
2.0
Affected Architecture:

Description

Shaper wizard results for basic config:

qOthersLow - LinkShare: 5%, 500ms, 5% < This is a flat curve and redundant., 5% for the first 500ms and then 5% after that.
qOthersHigh - LinkShare: 0b, 200ms, 10% < No traffic allowed until service curve opens up!
qAck - LinkShare: 0b, 100ms, 20% < No ACKs allowed until service curve opens up!

Fix: remove m1 and d service curve values to allow traffic to flow immediately. Advanced users can set service curves if they want/need them. Don't prevent traffic from flowing by default!

Files

Download all files
Screen_shot_2010-07-02_at_12.22.02_PM.png (39.3 KB) Screen_shot_2010-07-02_at_12.22.02_PM.png Aaron Berland, 07/02/2010 01:31 PM
Screen_shot_2010-07-02_at_12.22.16_PM.png (38.9 KB) Screen_shot_2010-07-02_at_12.22.16_PM.png Aaron Berland, 07/02/2010 01:31 PM
Screen_shot_2010-07-02_at_12.22.28_PM.png (37.1 KB) Screen_shot_2010-07-02_at_12.22.28_PM.png Aaron Berland, 07/02/2010 01:31 PM
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 #1

Updated by Ermal Luçi over 14 years ago

Can you please be more detailed on what the error is?

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 #2

Updated by Aaron Berland over 14 years ago

There is no error message output.

The shaper config functions, but logically is not correct. During congestion, having a service curve start at 0 bandwidth drops packets so the low priority queue gets the bandwidth while the higher priority queues are blocked for a moment. Performance is dramatically reduced for acks and high priority traffic during congestion.

I believe this is why qDefault and qOthersLow can get better performance than the higher priority queues and not allow maximum performance.

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 #3

Updated by Ermal Luçi over 14 years ago

  • Status changed from New to Feedback
  • % Done changed from 0 to 100
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 #4

Updated by Josh Stompro about 14 years ago

I can confirm this as resolved. The qACK and QOthersHigh get created without the Link Share M1 or D options set now. So qACK and QOthersHigh traffic does not get starved for a certain number of ms when the queue is full.

Tested with Dec 2nd nanobsd snapshot.

Thanks Ermal
Josh

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 #5

Updated by Ermal Luçi about 14 years ago

  • Status changed from Feedback to Resolved
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