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| /freebsd-10.0-release/sys/contrib/altq/altq/ | ||
| H A D | if_altq.h | diff 130384 Sat Jun 12 16:47:24 MDT 2004 mlaier 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. |
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