[Codel] The next slice of cake

[Jonathan Morton]

> On 22 Mar, 2015, at 11:39, Sebastian Moeller <moeller0 at gmx.de> wrote:
> 
> I could be out to lunch here, as usual,;but I argue the byte limit should include the kernel overhead (could this be based on skb->truesize) as this is what counts against real memory. My assumption here is that in normal operation we rarely/never get queues to fill up to the limit anyways

Such an argument could certainly be made.  Does skb->truesize include the skb header, as well as the buffer space allocated?

> (as tho would turn the queue into tail-drop effectively)

But fq_codel (and cake) are a little cleverer than that, even when they hit the hard limit.  They still drop from the head, and they shoot the longest flow-queue first.

 - Jonathan Morton