path: root/cddl/contrib
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authorMark Johnston <markj@FreeBSD.org>2020-02-28 16:05:18 +0000
committerMark Johnston <markj@FreeBSD.org>2020-02-28 16:05:18 +0000
commitc99d0c5801ce22a9976e491d04ce7e1b8996dfdd (patch)
treea7e90d5c78ec00f8619edaaeabf706ab037b1c9c /cddl/contrib
parentf37cc7137dc832aec317f0ba0bccde9436b5d9fb (diff)
Add a blocking counter KPI.
refcount(9) was recently extended to support waiting on a refcount to drop to zero, as this was needed for a lockless VM object paging-in-progress counter. However, this adds overhead to all uses of refcount(9) and doesn't really match traditional refcounting semantics: once a counter has dropped to zero, the protected object may be freed at any point and it is not safe to dereference the counter. This change removes that extension and instead adds a new set of KPIs, blockcount_*, for use by VM object PIP and busy. Reviewed by: jeff, kib, mjg Tested by: pho Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D23723
Notes: svn path=/head/; revision=358432
Diffstat (limited to 'cddl/contrib')
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