b1e239e6e2
Currently si_usecount is effectively a sum of usecounts from all associated vnodes. This is maintained by special-casing for VCHR every time usecount is modified. Apart from complicating the code a little bit, it has a scalability impact since it forces a read from a cacheline shared with said count. There are no consumers of the feature in the ports tree. In head there are only 2: revoke and devfs_close. Both can get away with a weaker requirement than the exact usecount, namely just the count of active vnodes. Changing the meaning to the latter means we only need to modify it on 0<->1 transitions, avoiding the check plenty of times (and entirely in something like vrefact). Reviewed by: kib, jeff Tested by: pho Differential Revision: https://reviews.freebsd.org/D22202 |
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devfs_devs.c | ||
devfs_dir.c | ||
devfs_int.h | ||
devfs_rule.c | ||
devfs_vfsops.c | ||
devfs_vnops.c | ||
devfs.h |