Date: Sat, 12 Jun 2004 18:47:25 +0000 (UTC) From: Max Laier <mlaier@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/contrib/altq/altq if_altq.h Message-ID: <200406121847.i5CIlPVt066137@repoman.freebsd.org>
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mlaier 2004-06-12 18:47:25 UTC
FreeBSD src repository
Modified files:
sys/contrib/altq/altq if_altq.h
Log:
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.
Revision Changes Path
1.2 +7 -0 src/sys/contrib/altq/altq/if_altq.h
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