import of old now defunct presentation slides svn repo

2 files changed, 240 insertions, 0 deletions

diff --git a/2004/linux2.6-networktour-lb2004/abstract b/2004/linux2.6-networktour-lb2004/abstract
new file mode 100644
index 0000000..ae466a0
--- /dev/null
+++ b/2004/linux2.6-networktour-lb2004/abstract
@@ -0,0 +1,4 @@
+Linux based systems are known for performance and realiability in the area of networking. This presentation will give a tour through the Linux 2.6 kernel network stack, it\'s structure and implementation. Some of the topics covered
+are: Network hardware drivers, core network functions, IPv4 protocol stack,
+destination cache, neighbour cache, sockets implementation, zero-copy TCP.
+
diff --git a/2004/linux2.6-networktour-lb2004/linux2.6-networktour-lb2004.mgp b/2004/linux2.6-networktour-lb2004/linux2.6-networktour-lb2004.mgp
new file mode 100644
index 0000000..7c52001
--- /dev/null
+++ b/2004/linux2.6-networktour-lb2004/linux2.6-networktour-lb2004.mgp
@@ -0,0 +1,236 @@
+%include "default.mgp"
+%default 1 bgrad
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+%nodefault
+%back "blue"
+
+
+
+%center
+%size 7
+A tour of the 
+Linux 2.6 network stack
+
+
+%center
+%size 4
+by
+
+Harald Welte <laforge@hmw-consulting.de>
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Contents
+
+
+	Introduction
+	Hardirq Context
+	Hard Interrupt Handler
+	Softirq Context
+	Network RX Softirq
+	IPv4 Packet Handler
+	IPv4 Packet Forwarding
+	IPv4 Packet Output
+	Driver TX routine
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page 
+Linux 2.6 Network Tour
+Introduction
+
+
+Who is speaking to you?
+		an independent Free Software developer
+		who earns his living off Free Software since 1997
+		who is one of the authors of the Linux kernel firewall system called netfilter/iptables
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Interrupt context
+
+	Also called 'hardirq'
+	Triggered by external interrupt to the cpu
+	Is not reentrant, because the irq is disabled before handler is called
+	Should only do minimum of work and leave as fast as possible
+
+	hardirq handler registered via request_irq()
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Receive Interrupt
+
+	NIC receives packet for local mac address
+	NIC issues interrupt
+	Interrupt is routed to one CPU
+	Kernel enters hardirq context and disables this irq on local cpu
+	Driver's interrupt handler
+		allocates skb (struct sk_buff)
+		calls net/core/dev.c:netif_rx()
+		return irqreturn_t	
+	Kernel leaves hardirq context and reenables this irq
+
+	2.6.x introduces NAPI for polling at high irq rates: netif_rx_schedule()
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Softirq context
+
+	Softirq is the real workhorse of interrupts
+	Continues work where hardirq has finished
+	Can be interrupted by hardirq context
+	Can run in parallel on any number of CPU's
+
+	softirq handler registered via kernel/softirq.c:open_softirq()
+
+	softirq's need to be 'raised' by raise_softirq() from hardirq
+	softirq's are scheduled
+		after hardirq context exits
+		from softirqd in case there's too much work
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Network RX Softirq
+
+
+	kernel/softirq.c:do_softirq()
+		generic softirq code
+	net/core/dev.c:net_rx_action()
+		function that is registered at open_softirq() time
+	net/core/dev.c:process_backlog()
+		dequeue skb from local CPU's backlog queue
+		uses a weighting scheme between different devices
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+netif_receive_skb()
+
+
+	net/core/dev.c:netif_receive_skb()
+		main network rx softirq workhorse
+		check if there are any netpoll users, if yes netpoll_rx()
+		if somebody requested skb rx timestamp, net_timestamp()
+		if interface is part of bound group, skb_bound()
+		tc ingress filtering: ing_filter()
+		packet diverter: handle_diverter()
+		bridging handler: net/core/dev.c:handle_bridge()
+		deliver to l3 protocol handler: net/core/dev.c:deliver_skb()
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+IPv4 packet handler
+
+
+	net/ipv4/ip_input.c:ip_rcv()
+		checksum check
+		size check
+		NF_IP_PRE_ROUTING netfilter hook
+	net/ipv4/ip_input.c:ip_rcv_finish()
+		net/ipv4/route.c/ip_route_input()
+			route/dst cache lookup
+			if lookup fails, ip_route_input_slow()
+				fib lookup
+				allocation of new dst_entry / rtable
+	include/net/dst.h:dst_input()
+		iterate over destination stack
+		call destination function of the respective stack items
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+IPv4 packet forwarding
+
+
+	net/ipv4/ip_forward.c:ip_forward()
+		xfrm4_policy_check()
+		router alert handling (ip_call_ra_chain)
+		ttl decrement
+		if route is redirect route, ip_rt_send_redirect()
+		call NF_IP_FORWARD netfilter hook
+	net/ipv4/ip_forward.c:ip_forward_finish()
+		increase statistics for snmp mib
+	include/net/dst.h:dst_output()
+		iterate over output functions of dst stack
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+IPv4 packet output
+
+
+	net/ipv4/ip_output.c:ip_output()
+		fragment packet via ip_fragment() if needed
+	net/ipv4/ip_output.c:ip_finish_output()
+		call netfilter NF_IP_POST_ROUTING hook
+	net/ipv4/ip_output.c:ip_finish_output2()
+		attach hardware header
+		call header cache output fn (if neighbour in cache) 
+			net/core/dev.c:dev_skb_xmit()
+		or neighbour output function (if neighbour unknown)
+			net/core/neighbour.c:neigh_resolve_output()
+	
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+dev_skb_xmit()
+
+
+	skb->dev->qdisc->enqueue()
+		enqueue into devices output queue 
+	default: net/sched/sch_generic.c:pfifo_fast_enqueue()
+	net/sched/sch_generic.c:qdisc_restart():
+		dev->qdisc->dequeue()
+			dequeue skb from queue
+		dev->hard_start_xmit()
+			transmit skb via driver
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Driver TX Routine
+	
+	drivers/net/e1000/e1000_main.c:e1000_xmit_frame()
+		tons of workarounds for chip bugs
+		set up TX DMA descriptor
+		queue TX DMA descriptor to device hardware
+		return NETDEV_TX_OK
+
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%page
+Linux 2.6 Network Tour
+Thanks
+
+	Thanks to
+		Alan Cox, Alexey Kuznetsov, David Miller, Andi Kleen
+			for implementing (one of?) the world's best TCP/IP stacks
+		Paul 'Rusty' Russell
+			for starting the netfilter/iptables project
+			for trusting me to maintain it today
+		Astaro AG
+			for sponsoring parts of my netfilter work
+		Free Software Foundation
+			for the GNU Project 
+			for the GNU General Public License
+%size 3
+	The slides of this presentation are available at http://www.gnumonks.org/
+
+	Further Reading
+%size 3
+	The netfilter homepage http://www.netfilter.org/
+%size 3
+	The http://www.gpl-violations.org/ project
+
+