Re: [PATCH net-next] net_sched: sfq: extend limits

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 05 Jan 2012 01:18:38 +0100

> SFQ as implemented in Linux is very limited, with at most 127 flows
> and limit of 127 packets. [ So if 127 flows are active, we have one
> packet per flow ]
> 
> This patch brings to SFQ following features to cope with modern needs.
> 
> - Ability to specify a smaller per flow limit of inflight packets.
>     (default value being at 127 packets)
> 
> - Ability to have up to 65408 active flows (instead of 127)
> 
> - Ability to have head drops instead of tail drops
>   (to drop old packets from a flow)
> 
> Example of use : No more than 20 packets per flow, max 8000 flows, max
> 20000 packets in SFQ qdisc, hash table of 65536 slots.
> 
> tc qdisc add ... sfq \
>         flows 8000 \
>         depth 20 \
>         headdrop \
>         limit 20000 \
> 	divisor 65536
> 
> Ram usage : 
> 
> 2 bytes per hash table entry (instead of previous 1 byte/entry)
> 32 bytes per flow on 64bit arches, instead of 384 for QFQ, so much
> better cache hit ratio.
> 
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Applied.