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| author | mlaier <mlaier@FreeBSD.org> | 2004-06-12 18:47:24 +0000 |
|---|---|---|
| committer | mlaier <mlaier@FreeBSD.org> | 2004-06-12 18:47:24 +0000 |
| commit | 8a4d60fb93b14b5a3d3a50dccd975dc9b633a2e3 (patch) | |
| tree | 037f7f4a3db852989b06a857dce96f3a4ffc9c77 /sys/contrib | |
| parent | dc268bcf6a44b920628b2aa0d735b2f3d95e2958 (diff) | |
| download | FreeBSD-src-8a4d60fb93b14b5a3d3a50dccd975dc9b633a2e3.zip FreeBSD-src-8a4d60fb93b14b5a3d3a50dccd975dc9b633a2e3.tar.gz | |
Add an additional queue which will be "owned by the driver". This allows to
rig a PREPEND macro for ALTQ as the POLL/DEQUEUE semantic is very bad in
terms of locking. We make this a full functional queue to allow "bulk
dequeue" which will further reduce the locking overhead (for non-altq
enabled devices). Drivers will access this via the following macros, which
will show up in <net/if_var.h> once we expose ALTQ to the build:
IFQ_DRV_DEQUEUE(ifq, m) - takes a mbuf off the queue (driver queue first)
IFQ_DRV_PREPEND(ifq, m) - pushes a mbuf back to the driver queue
IFQ_DRV_PURGE(ifq) - drops all packets in both queues
IFQ_DRV_IS_EMPTY(ifq) - checks for pending mbufs in either queue
One has to make sure that the first three are protected by a driver mutex.
At the moment most network drivers still require Giant, so this is not an
issue. Even those that have thier own mutex usually hold it in if_start and
the like, so this requirement is almost always satisfied.
This evolved from a discussion with Andrew Gallatin.
Diffstat (limited to 'sys/contrib')
| -rw-r--r-- | sys/contrib/altq/altq/if_altq.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sys/contrib/altq/altq/if_altq.h b/sys/contrib/altq/altq/if_altq.h index 8abb6a6..8e60587 100644 --- a/sys/contrib/altq/altq/if_altq.h +++ b/sys/contrib/altq/altq/if_altq.h @@ -1,3 +1,4 @@ +/* $FreeBSD$ */ /* $KAME: if_altq.h,v 1.11 2003/07/10 12:07:50 kjc Exp $ */ /* @@ -54,6 +55,12 @@ struct ifaltq { struct mtx ifq_mtx; #endif + /* driver owned queue (used for bulk dequeue and prepend) UNLOCKED */ + struct mbuf *ifq_drv_head; + struct mbuf *ifq_drv_tail; + int ifq_drv_len; + int ifq_drv_maxlen; + /* alternate queueing related fields */ int altq_type; /* discipline type */ int altq_flags; /* flags (e.g. ready, in-use) */ |
