Re: Real time issues when using a bridge

[Jean-Michel Hautbois <jhautbois@xxxxxxxxx>]

2010/10/12 Stephen Hemminger <shemminger@xxxxxxxxxxxxxxxxxxxx>

> Thus, my jitter is 47Âs.
> This may seem low, but this is about two to three times what I expect and I
> cannot see why a bridge which is only forwarding a frame would have jitter ?
> If you have any idea, everything is interesting for me.
> I thought maybe to skb_clone ?

You probably have NAPI and/or interrupt coalescing setting
enabled on one or both of the devices.

--

Hi Stephen,

I have NAPI on my ethernet device, at least.
I will check for interrupt coalescing.
AFAIK, there is a skb_clone followed by a kfree in netif_receive_skb (the frame coming from eth0 to br0).
There is a jitter in this call of "freeing memory". I am looking at the path, in order to see why there is a clone.

BR,
JM
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