Date: Sat, 9 Oct 2004 22:04:13 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@FreeBSD.org, cvs-src@FreeBSD.org, cvs-all@FreeBSD.org Subject: cvs commit: src/sys/dev/random randomdev_soft.c Message-ID: <200410092204.i99M4Dl7026960@repoman.freebsd.org>
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rwatson 2004-10-09 22:04:13 UTC
FreeBSD src repository
Modified files:
sys/dev/random randomdev_soft.c
Log:
Modify entropy harvesting locking strategy:
- Trade off granularity to reduce overhead, since the current model
doesn't appear to reduce contention substantially: move to a single
harvest mutex protecting harvesting queues, rather than one mutex
per source plus a mutex for the free list.
- Reduce mutex operations in a harvesting event to 2 from 4, and
maintain lockless read to avoid mutex operations if the queue is
full.
- When reaping harvested entries from the queue, move all entries from
the queue at once, and when done with them, insert them all into a
thread-local queue for processing; then insert them all into the
empty fifo at once. This reduces O(4n) mutex operations to O(2)
mutex operations per wakeup.
In the future, we may want to look at re-introducing granularity,
although perhaps at the granularity of the source rather than the
source class; both the new and old strategies would cause contention
between different instances of the same source (i.e., multiple
network interfaces).
Reviewed by: markm
Revision Changes Path
1.5 +41 -50 src/sys/dev/random/randomdev_soft.c
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