Thread (4 messages) flat view 4 messages, 2 authors, 2012-01-19

problem with noop and pfifo_fast Qdisc switching

From: Hemant-vilas RAMDASI <hidden>
Date: 2012-01-19 12:47:46

Hi,

I have a situation where one of important message (phonet pipe message) gets dropped because of 'noop' Qdisc.
This situation mostly happens when coming out of sleep and there is a message to send.
What I have observed is this.
In normal case the qdisc used id pfifo_fast. When CPU goes to sleep, it changes the qdisc to noop.
When CPU wakes up (because of a message from lower layers), phonet tries to send a control packet to driver and finds qdisc is still 'noop'. 
Because the concerned message is a control message, this packet drop is creating deadlock situation.

How the switch between pfifo_fast and noop is handled? Is this something solved in 3.0?
We are running a older version of kernel (2.6.35 based).

Thanks,
Hemant
 
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