8e7c23d74f
interested in ALTQ are likely to type in "man altq" at some point and maybe they will scroll down to the bottom as well. MFC after: 3 days
635 lines
19 KiB
Groff
635 lines
19 KiB
Groff
.\" $NetBSD: altq.9,v 1.8 2002/05/28 11:41:45 wiz Exp $
|
|
.\" $OpenBSD: altq.9,v 1.4 2001/07/12 12:41:42 itojun Exp $
|
|
.\"
|
|
.\" Copyright (C) 2004 Max Laier. All rights reserved.
|
|
.\" Copyright (C) 2001
|
|
.\" Sony Computer Science Laboratories Inc. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY SONY CSL AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL SONY CSL OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd August 25, 2004
|
|
.Dt ALTQ 9
|
|
.Os
|
|
.\"
|
|
.Sh NAME
|
|
.Nm ALTQ
|
|
.Nd kernel interfaces for manipulating output queues on network interfaces
|
|
.Sh SYNOPSIS
|
|
.In sys/types.h
|
|
.In sys/socket.h
|
|
.In net/if.h
|
|
.In net/if_var.h
|
|
.\"
|
|
.Ss Enqueue macros
|
|
.Fn IFQ_ENQUEUE "struct ifaltq *ifq" "struct mbuf *m" "int error"
|
|
.Fn IFQ_HANDOFF "struct ifnet *ifp" "struct mbuf *m" "int error"
|
|
.Fo IFQ_HANDOFF_ADJ
|
|
.Fa "struct ifnet *ifp" "struct mbuf *m" "int adjust" "int error"
|
|
.Fc
|
|
.\"
|
|
.Ss Dequeue macros
|
|
.Fn IFQ_DEQUEUE "struct ifaltq *ifq" "struct mbuf *m"
|
|
.Fn IFQ_POLL_NOLOCK "struct ifaltq *ifq" "struct mbuf *m"
|
|
.Fn IFQ_PURGE "struct ifaltq *ifq"
|
|
.Fn IFQ_IS_EMPTY "struct ifaltq *ifq"
|
|
.\"
|
|
.Ss Driver managed dequeue macros
|
|
.Fn IFQ_DRV_DEQUEUE "struct ifaltq *ifq" "struct mbuf *m"
|
|
.Fn IFQ_DRV_PREPEND "struct ifaltq *ifq" "struct mbuf *m"
|
|
.Fn IFQ_DRV_PURGE "struct ifaltq *ifq"
|
|
.Fn IFQ_DRV_IS_EMPTY "struct ifaltq *ifq"
|
|
.\"
|
|
.Ss General setup macros
|
|
.Fn IFQ_SET_MAXLEN "struct ifaltq *ifq" "int len"
|
|
.Fn IFQ_INC_LEN "struct ifaltq *ifq"
|
|
.Fn IFQ_DEC_LEN "struct ifaltq *ifq"
|
|
.Fn IFQ_INC_DROPS "struct ifaltq *ifq"
|
|
.Fn IFQ_SET_READY "struct ifaltq *ifq"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
system is a framework to manage queuing disciplines on network
|
|
interfaces.
|
|
.Nm
|
|
introduces new macros to manipulate output queues.
|
|
The output queue macros are used to abstract queue operations and not to
|
|
touch the internal fields of the output queue structure.
|
|
The macros are independent from the
|
|
.Nm
|
|
implementation, and compatible with the traditional
|
|
.Vt ifqueue
|
|
macros for ease of transition.
|
|
.Pp
|
|
.Fn IFQ_ENQUEUE ,
|
|
.Fn IFQ_HANDOFF
|
|
and
|
|
.Fn IFQ_HANDOFF_ADJ
|
|
enqueue a packet
|
|
.Fa m
|
|
to the queue
|
|
.Fa ifq .
|
|
The underlying queuing discipline may discard the packet.
|
|
The
|
|
.Fa error
|
|
argument is set to 0 on success, or
|
|
.Er ENOBUFS
|
|
if the packet is discarded.
|
|
The packet pointed to by
|
|
.Fa m
|
|
will be freed by the device driver on success, or by the queuing discipline on
|
|
failure, so the caller should not touch
|
|
.Fa m
|
|
after enqueuing.
|
|
.Fn IFQ_HANDOFF
|
|
and
|
|
.Fn IFQ_HANDOFF_ADJ
|
|
combine the enqueue operation with statistic generation and call
|
|
.Fn if_start
|
|
upon successful enqueue to initiate the actual send.
|
|
.Pp
|
|
.Fn IFQ_DEQUEUE
|
|
dequeues a packet from the queue.
|
|
The dequeued packet is returned in
|
|
.Fa m ,
|
|
or
|
|
.Fa m
|
|
is set to
|
|
.Dv NULL
|
|
if no packet is dequeued.
|
|
The caller must always check
|
|
.Fa m
|
|
since a non-empty queue could return
|
|
.Dv NULL
|
|
under rate-limiting.
|
|
.Pp
|
|
.Fn IFQ_POLL_NOLOCK
|
|
returns the next packet without removing it from the queue.
|
|
The caller must hold the queue mutex when calling
|
|
.Fn IFQ_POLL_NOLOCK
|
|
in order to guarantee that a subsequent call to
|
|
.Fn IFQ_DEQUEUE_NOLOCK
|
|
dequeues the same packet.
|
|
.Pp
|
|
.Fn IFQ_*_NOLOCK
|
|
variants (if available) always assume that the caller holds the queue mutex.
|
|
They can be grabbed with
|
|
.Fn IFQ_LOCK
|
|
and released with
|
|
.Fn IFQ_UNLOCK .
|
|
.Pp
|
|
.Fn IFQ_PURGE
|
|
discards all the packets in the queue.
|
|
The purge operation is needed since a non-work conserving queue cannot be
|
|
emptied by a dequeue loop.
|
|
.Pp
|
|
.Fn IFQ_IS_EMPTY
|
|
can be used to check if the queue is empty.
|
|
Note that
|
|
.Fn IFQ_DEQUEUE
|
|
could still return
|
|
.Dv NULL
|
|
if the queuing discipline is non-work conserving.
|
|
.Pp
|
|
.Fn IFQ_DRV_DEQUEUE
|
|
moves up to
|
|
.Fa ifq->ifq_drv_maxlen
|
|
packets from the queue to the
|
|
.Dq "driver managed"
|
|
queue and returns the first one via
|
|
.Fa m .
|
|
As for
|
|
.Fn IFQ_DEQUEUE ,
|
|
.Fa m
|
|
can be
|
|
.Dv NULL
|
|
even for a non-empty queue.
|
|
Subsequent calls to
|
|
.Fn IFQ_DRV_DEQUEUE
|
|
pass the packets from the
|
|
.Dq "driver managed"
|
|
queue without obtaining the queue mutex.
|
|
It is the responsibility of the caller to protect against concurrent access.
|
|
Enabling
|
|
.Nm
|
|
for a given queue sets
|
|
.Va ifq_drv_maxlen
|
|
to 0 as the
|
|
.Dq "bulk dequeue"
|
|
performed by
|
|
.Fn IFQ_DRV_DEQUEUE
|
|
for higher values of
|
|
.Va ifq_drv_maxlen
|
|
is adverse to
|
|
.Nm ALTQ Ns 's
|
|
internal timing.
|
|
Note that a driver must not mix
|
|
.Fn IFQ_DRV_*
|
|
macros with the default dequeue macros as the default macros do not look at the
|
|
.Dq "driver managed"
|
|
queue which might lead to an mbuf leak.
|
|
.Pp
|
|
.Fn IFQ_DRV_PREPEND
|
|
prepends
|
|
.Fa m
|
|
to the
|
|
.Dq "driver managed"
|
|
queue from where it will be obtained with the next call to
|
|
.Fn IFQ_DRV_DEQUEUE .
|
|
.Pp
|
|
.Fn IFQ_DRV_PURGE
|
|
flushes all packets in the
|
|
.Dq "driver managed"
|
|
queue and calls to
|
|
.Fn IFQ_PURGE
|
|
afterwards.
|
|
.Pp
|
|
.Fn IFQ_DRV_IS_EMPTY
|
|
checks for packets in the
|
|
.Dq "driver managed"
|
|
part of the queue.
|
|
If it is empty, it forwards to
|
|
.Fn IFQ_IS_EMPTY .
|
|
.Pp
|
|
.Fn IFQ_SET_MAXLEN
|
|
sets the queue length limit to the default FIFO queue.
|
|
The
|
|
.Va ifq_drv_maxlen
|
|
member of the
|
|
.Vt ifaltq
|
|
structure controls the length limit of the
|
|
.Dq "driver managed"
|
|
queue.
|
|
.Pp
|
|
.Fn IFQ_INC_LEN
|
|
and
|
|
.Fn IFQ_DEC_LEN
|
|
increment or decrement the current queue length in packets.
|
|
This is mostly for internal purposes.
|
|
.Pp
|
|
.Fn IFQ_INC_DROPS
|
|
increments the drop counter and is identical to
|
|
.Fn IF_DROP .
|
|
It is defined for naming consistency only.
|
|
.Pp
|
|
.Fn IFQ_SET_READY
|
|
sets a flag to indicate that a driver was converted to use the new macros.
|
|
.Nm
|
|
can be enabled only on interfaces with this flag.
|
|
.Sh COMPATIBILITY
|
|
.Ss Vt ifaltq Ss structure
|
|
In order to keep compatibility with the existing code, the new
|
|
output queue structure
|
|
.Vt ifaltq
|
|
has the same fields.
|
|
The traditional
|
|
.Fn IF_*
|
|
macros and the code directly referencing the fields within
|
|
.Va if_snd
|
|
still work with
|
|
.Vt ifaltq .
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
struct ifqueue { | struct ifaltq {
|
|
struct mbuf *ifq_head; | struct mbuf *ifq_head;
|
|
struct mbuf *ifq_tail; | struct mbuf *ifq_tail;
|
|
int ifq_len; | int ifq_len;
|
|
int ifq_maxlen; | int ifq_maxlen;
|
|
int ifq_drops; | int ifq_drops;
|
|
}; | /* driver queue fields */
|
|
| ......
|
|
| /* altq related fields */
|
|
| ......
|
|
| };
|
|
|
|
|
.Ed
|
|
The new structure replaces
|
|
.Vt "struct ifqueue"
|
|
in
|
|
.Vt "struct ifnet" .
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
struct ifnet { | struct ifnet {
|
|
.... | ....
|
|
|
|
|
struct ifqueue if_snd; | struct ifaltq if_snd;
|
|
|
|
|
.... | ....
|
|
}; | };
|
|
|
|
|
.Ed
|
|
The (simplified) new
|
|
.Fn IFQ_*
|
|
macros look like:
|
|
.Bd -literal
|
|
#define IFQ_DEQUEUE(ifq, m) \e
|
|
if (ALTQ_IS_ENABLED((ifq)) \e
|
|
ALTQ_DEQUEUE((ifq), (m)); \e
|
|
else \e
|
|
IF_DEQUEUE((ifq), (m));
|
|
.Ed
|
|
.Ss Enqueue operation
|
|
The semantics of the enqueue operation is changed.
|
|
In the new style,
|
|
enqueue and packet drop are combined since they cannot be easily
|
|
separated in many queuing disciplines.
|
|
The new enqueue operation corresponds to the following macro that is
|
|
written with the old macros.
|
|
.Bd -literal
|
|
#define IFQ_ENQUEUE(ifq, m, error) \e
|
|
do { \e
|
|
if (IF_QFULL((ifq))) { \e
|
|
m_freem((m)); \e
|
|
(error) = ENOBUFS; \e
|
|
IF_DROP(ifq); \e
|
|
} else { \e
|
|
IF_ENQUEUE((ifq), (m)); \e
|
|
(error) = 0; \e
|
|
} \e
|
|
} while (0)
|
|
.Ed
|
|
.Pp
|
|
.Fn IFQ_ENQUEUE
|
|
does the following:
|
|
.Pp
|
|
.Bl -hyphen -compact
|
|
.It
|
|
queue a packet,
|
|
.It
|
|
drop (and free) a packet if the enqueue operation fails.
|
|
.El
|
|
.Pp
|
|
If the enqueue operation fails,
|
|
.Fa error
|
|
is set to
|
|
.Er ENOBUFS .
|
|
The
|
|
.Fa m
|
|
mbuf is freed by the queuing discipline.
|
|
The caller should not touch mbuf after calling
|
|
.Fn IFQ_ENQUEUE
|
|
so that the caller may need to copy
|
|
.Va m_pkthdr.len
|
|
or
|
|
.Va m_flags
|
|
field beforehand for statistics.
|
|
.Fn IFQ_HANDOFF
|
|
and
|
|
.Fn IFQ_HANDOFF_ADJ
|
|
can be used if only default interface statistics and an immediate call to
|
|
.Fn if_start
|
|
are desired.
|
|
The caller should not use
|
|
.Fn senderr
|
|
since mbuf was already freed.
|
|
.Pp
|
|
The new style
|
|
.Fn if_output
|
|
looks as follows:
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
int | int
|
|
ether_output(ifp, m0, dst, rt0) | ether_output(ifp, m0, dst, rt0)
|
|
{ | {
|
|
...... | ......
|
|
|
|
|
| mflags = m->m_flags;
|
|
| len = m->m_pkthdr.len;
|
|
s = splimp(); | s = splimp();
|
|
if (IF_QFULL(&ifp->if_snd)) { | IFQ_ENQUEUE(&ifp->if_snd, m,
|
|
| error);
|
|
IF_DROP(&ifp->if_snd); | if (error != 0) {
|
|
splx(s); | splx(s);
|
|
senderr(ENOBUFS); | return (error);
|
|
} | }
|
|
IF_ENQUEUE(&ifp->if_snd, m); |
|
|
ifp->if_obytes += | ifp->if_obytes += len;
|
|
m->m_pkthdr.len; |
|
|
if (m->m_flags & M_MCAST) | if (mflags & M_MCAST)
|
|
ifp->if_omcasts++; | ifp->if_omcasts++;
|
|
|
|
|
if ((ifp->if_flags & IFF_OACTIVE) | if ((ifp->if_flags & IFF_OACTIVE)
|
|
== 0) | == 0)
|
|
(*ifp->if_start)(ifp); | (*ifp->if_start)(ifp);
|
|
splx(s); | splx(s);
|
|
return (error); | return (error);
|
|
|
|
|
bad: | bad:
|
|
if (m) | if (m)
|
|
m_freem(m); | m_freem(m);
|
|
return (error); | return (error);
|
|
} | }
|
|
|
|
|
.Ed
|
|
.Sh HOW TO CONVERT THE EXISTING DRIVERS
|
|
First, make sure the corresponding
|
|
.Fn if_output
|
|
is already converted to the new style.
|
|
.Pp
|
|
Look for
|
|
.Va if_snd
|
|
in the driver.
|
|
Probably, you need to make changes to the lines that include
|
|
.Va if_snd .
|
|
.Ss Empty check operation
|
|
If the code checks
|
|
.Va ifq_head
|
|
to see whether the queue is empty or not, use
|
|
.Fn IFQ_IS_EMPTY .
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
if (ifp->if_snd.ifq_head != NULL) | if (!IFQ_IS_EMPTY(&ifp->if_snd))
|
|
|
|
|
.Ed
|
|
.Fn IFQ_IS_EMPTY
|
|
only checks if there is any packet stored in the queue.
|
|
Note that even when
|
|
.Fn IFQ_IS_EMPTY
|
|
is
|
|
.Dv FALSE ,
|
|
.Fn IFQ_DEQUEUE
|
|
could still return
|
|
.Dv NULL
|
|
if the queue is under rate-limiting.
|
|
.Ss Dequeue operation
|
|
Replace
|
|
.Fn IF_DEQUEUE
|
|
by
|
|
.Fn IFQ_DEQUEUE .
|
|
Always check whether the dequeued mbuf is
|
|
.Dv NULL
|
|
or not.
|
|
Note that even when
|
|
.Fn IFQ_IS_EMPTY
|
|
is
|
|
.Dv FALSE ,
|
|
.Fn IFQ_DEQUEUE
|
|
could return
|
|
.Dv NULL
|
|
due to rate-limiting.
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
IF_DEQUEUE(&ifp->if_snd, m); | IFQ_DEQUEUE(&ifp->if_snd, m);
|
|
| if (m == NULL)
|
|
| return;
|
|
|
|
|
.Ed
|
|
A driver is supposed to call
|
|
.Fn if_start
|
|
from transmission complete interrupts in order to trigger the next dequeue.
|
|
.Ss Poll-and-dequeue operation
|
|
If the code polls the packet at the head of the queue and actually uses
|
|
the packet before dequeuing it, use
|
|
.Fn IFQ_POLL_NOLOCK
|
|
and
|
|
.Fn IFQ_DEQUEUE_NOLOCK .
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
| IFQ_LOCK(&ifp->if_snd);
|
|
m = ifp->if_snd.ifq_head; | IFQ_POLL_NOLOCK(&ifp->if_snd, m);
|
|
if (m != NULL) { | if (m != NULL) {
|
|
|
|
|
/* use m to get resources */ | /* use m to get resources */
|
|
if (something goes wrong) | if (something goes wrong)
|
|
| IFQ_UNLOCK(&ifp->if_snd);
|
|
return; | return;
|
|
|
|
|
IF_DEQUEUE(&ifp->if_snd, m); | IFQ_DEQUEUE_NOLOCK(&ifp->if_snd, m);
|
|
| IFQ_UNLOCK(&ifp->if_snd);
|
|
|
|
|
/* kick the hardware */ | /* kick the hardware */
|
|
} | }
|
|
|
|
|
.Ed
|
|
It is guaranteed that
|
|
.Fn IFQ_DEQUEUE_NOLOCK
|
|
under the same lock as a previous
|
|
.Fn IFQ_POLL_NOLOCK
|
|
returns the same packet.
|
|
Note that they need to be guarded by
|
|
.Fn IFQ_LOCK .
|
|
.Ss Eliminating Fn IF_PREPEND
|
|
If the code uses
|
|
.Fn IF_PREPEND ,
|
|
you have to eliminate it unless you can use a
|
|
.Dq "driver managed"
|
|
queue which allows the use of
|
|
.Fn IFQ_DRV_PREPEND
|
|
as a substitute.
|
|
A common usage of
|
|
.Fn IF_PREPEND
|
|
is to cancel the previous dequeue operation.
|
|
You have to convert the logic into poll-and-dequeue.
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
| IFQ_LOCK(&ifp->if_snd);
|
|
IF_DEQUEUE(&ifp->if_snd, m); | IFQ_POLL_NOLOCK(&ifp->if_snd, m);
|
|
if (m != NULL) { | if (m != NULL) {
|
|
|
|
|
if (something_goes_wrong) { | if (something_goes_wrong) {
|
|
IF_PREPEND(&ifp->if_snd, m); | IFQ_UNLOCK(&ifp->if_snd);
|
|
return; | return;
|
|
} | }
|
|
|
|
|
| /* at this point, the driver
|
|
| * is committed to send this
|
|
| * packet.
|
|
| */
|
|
| IFQ_DEQUEUE_NOLOCK(&ifp->if_snd, m);
|
|
| IFQ_UNLOCK(&ifp->if_snd);
|
|
|
|
|
/* kick the hardware */ | /* kick the hardware */
|
|
} | }
|
|
|
|
|
.Ed
|
|
.Ss Purge operation
|
|
Use
|
|
.Fn IFQ_PURGE
|
|
to empty the queue.
|
|
Note that a non-work conserving queue cannot be emptied by a dequeue loop.
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
while (ifp->if_snd.ifq_head != NULL) {| IFQ_PURGE(&ifp->if_snd);
|
|
IF_DEQUEUE(&ifp->if_snd, m); |
|
|
m_freem(m); |
|
|
} |
|
|
|
|
|
.Ed
|
|
.Ss Conversion using a driver managed queue
|
|
Convert
|
|
.Fn IF_*
|
|
macros to their equivalent
|
|
.Fn IFQ_DRV_*
|
|
and employ
|
|
.Fn IFQ_DRV_IS_EMPTY
|
|
where appropriate.
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
if (ifp->if_snd.ifq_head != NULL) | if (!IFQ_DRV_IS_EMPTY(&ifp->if_snd))
|
|
|
|
|
.Ed
|
|
Make sure that calls to
|
|
.Fn IFQ_DRV_DEQUEUE ,
|
|
.Fn IFQ_DRV_PREPEND
|
|
and
|
|
.Fn IFQ_DRV_PURGE
|
|
are protected with a mutex of some kind.
|
|
Setting
|
|
.Dv IFF_NEEDSGIANT
|
|
in
|
|
.Va if_flags
|
|
might also be appropriate.
|
|
.Ss Attach routine
|
|
Use
|
|
.Fn IFQ_SET_MAXLEN
|
|
to set
|
|
.Va ifq_maxlen
|
|
to
|
|
.Fa len .
|
|
Initialize
|
|
.Va ifq_drv_maxlen
|
|
with a sensible value if you plan to use the
|
|
.Fn IFQ_DRV_*
|
|
macros.
|
|
Add
|
|
.Fn IFQ_SET_READY
|
|
to show this driver is converted to the new style.
|
|
(This is used to distinguish new-style drivers.)
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
ifp->if_snd.ifq_maxlen = qsize; | IFQ_SET_MAXLEN(&ifp->if_snd, qsize);
|
|
| ifp->if_snd.ifq_drv_maxlen = qsize;
|
|
| IFQ_SET_READY(&ifp->if_snd);
|
|
if_attach(ifp); | if_attach(ifp);
|
|
|
|
|
.Ed
|
|
.Ss Other issues
|
|
The new macros for statistics:
|
|
.Bd -literal
|
|
##old-style## ##new-style##
|
|
|
|
|
IF_DROP(&ifp->if_snd); | IFQ_INC_DROPS(&ifp->if_snd);
|
|
|
|
|
ifp->if_snd.ifq_len++; | IFQ_INC_LEN(&ifp->if_snd);
|
|
|
|
|
ifp->if_snd.ifq_len--; | IFQ_DEC_LEN(&ifp->if_snd);
|
|
|
|
|
.Ed
|
|
.Sh QUEUING DISCIPLINES
|
|
Queuing disciplines need to maintain
|
|
.Fa ifq_len
|
|
(used by
|
|
.Fn IFQ_IS_EMPTY ) .
|
|
Queuing disciplines also need to guarantee that the same mbuf is returned if
|
|
.Fn IFQ_DEQUEUE
|
|
is called immediately after
|
|
.Fn IFQ_POLL .
|
|
.Sh SUPPORTED DEVICES
|
|
The herein described modifications have been applied to the following
|
|
hardware drivers
|
|
.Xr an 4 ,
|
|
.Xr ath 4 ,
|
|
.Xr awi 4 ,
|
|
.Xr bfe 4 ,
|
|
.Xr em 4 ,
|
|
.Xr fxp 4 ,
|
|
.Xr hme 4 ,
|
|
.Xr lnc 4 ,
|
|
.Xr wi 4 ,
|
|
.Xr de 4 ,
|
|
.Xr rl 4 ,
|
|
.Xr sis 4 ,
|
|
.Xr vr 4
|
|
and
|
|
.Xr xl 4 .
|
|
.Pp
|
|
The
|
|
.Xr ndis 4
|
|
framework also has support for
|
|
.Nm
|
|
and thus all encapsulated drivers.
|
|
.Pp
|
|
The
|
|
.Xr tun 4
|
|
pseudo driver also does support
|
|
.Nm
|
|
and includes the required modifications.
|
|
.Sh SEE ALSO
|
|
.Xr pf 4 ,
|
|
.Xr pf.conf 5 ,
|
|
.Xr pfctl 8
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
system first appeared in March 1997.
|