linux/net/sched
Herbert Xu 48d83325b6 [NET]: Prevent multiple qdisc runs
Having two or more qdisc_run's contend against each other is bad because
it can induce packet reordering if the packets have to be requeued.  It
appears that this is an unintended consequence of relinquinshing the queue
lock while transmitting.  That in turn is needed for devices that spend a
lot of time in their transmit routine.

There are no advantages to be had as devices with queues are inherently
single-threaded (the loopback device is not but then it doesn't have a
queue).

Even if you were to add a queue to a parallel virtual device (e.g., bolt
a tbf filter in front of an ipip tunnel device), you would still want to
process the queue in sequence to ensure that the packets are ordered
correctly.

The solution here is to steal a bit from net_device to prevent this.

BTW, as qdisc_restart is no longer used by anyone as a module inside the
kernel (IIRC it used to with netif_wake_queue), I have not exported the
new __qdisc_run function.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
2006-06-19 23:57:59 -07:00
..
act_api.c [NET_SCHED]: act_api: fix skb leak in error path 2006-03-12 20:39:36 -08:00
act_gact.c
act_ipt.c [NETFILTER]: ipt action: use xt_check_target for basic verification 2006-04-24 17:27:34 -07:00
act_mirred.c
act_pedit.c
act_police.c [PKT_SCHED] act_police: Rename methods. 2006-04-09 22:25:46 -07:00
act_simple.c
cls_api.c
cls_basic.c
cls_fw.c
cls_route.c
cls_rsvp6.c
cls_rsvp.c
cls_rsvp.h
cls_tcindex.c
cls_u32.c [NET_SCHED]: cls_u32: remove unnecessary NULL-ptr check 2006-03-23 01:16:48 -08:00
em_cmp.c
em_meta.c
em_nbyte.c
em_text.c
em_u32.c
ematch.c
estimator.c
Kconfig [PKT_SCHED]: Let NET_CLS_ACT no longer depend on EXPERIMENTAL 2006-03-20 22:44:24 -08:00
Makefile
sch_api.c
sch_atm.c
sch_blackhole.c
sch_cbq.c
sch_dsmark.c
sch_fifo.c
sch_generic.c [NET]: Prevent multiple qdisc runs 2006-06-19 23:57:59 -07:00
sch_gred.c
sch_hfsc.c [NET_SCHED]: HFSC: fix thinko in hfsc_adjust_levels() 2006-05-11 12:22:03 -07:00
sch_htb.c
sch_ingress.c
sch_netem.c [PKT_SCHED] netem: fix loss 2006-04-29 18:33:12 -07:00
sch_prio.c [PKT_SCHED]: Qdisc drop operation is optional 2006-03-20 19:00:49 -08:00
sch_red.c [PKT_SCHED]: Convert sch_red to a classful qdisc 2006-03-20 19:20:44 -08:00
sch_sfq.c [PKT_SCHED]: Keep backlog counter in sch_sfq 2006-03-20 19:01:38 -08:00
sch_tbf.c
sch_teql.c [NET]: Add netif_tx_lock 2006-06-17 21:30:14 -07:00