Module Name: src
Committed By: ad
Date: Sun Dec 1 13:39:53 UTC 2019
Modified Files:
src/sys/kern: vfs_cache.c
src/sys/rump/include/rump: rump_namei.h
src/sys/sys: namei.h namei.src
Log Message:
namecache changes:
- Delete the per-entry lock, and borrow the associated vnode's v_interlock
instead. We need to acquire it during lookup anyway. We can revisit this
in the future but for now it's a stepping stone, and works within the
quite limited context of what we have (BSD namecache/lookup design).
- Implement an idea that Mateusz Guzik (m...@freebsd.org) gave me. In
cache_reclaim(), we don't need to lock out all of the CPUs to garbage
collect entries. All we need to do is observe their locks unheld at least
once: then we know they are not in the critical section, and no longer
have visibility of the entries about to be garbage collected.
- The above makes it safe for sysctl to take only namecache_lock to get stats,
and we can remove all the crap dealing with per-CPU locks.
- For lockstat, make namecache_lock a static now we have __cacheline_aligned.
- Avoid false sharing - don't write back to nc_hittime unless it has changed.
Put a a comment in place explaining this. Pretty sure this was there in
2008/2009 but someone removed it (understandably, the code looks weird).
- Use a mutex to protect the garbage collection queue instead of atomics, and
adjust the low water mark up so that cache_reclaim() isn't doing so much
work at once.
To generate a diff of this commit:
cvs rdiff -u -r1.123 -r1.124 src/sys/kern/vfs_cache.c
cvs rdiff -u -r1.33 -r1.34 src/sys/rump/include/rump/rump_namei.h
cvs rdiff -u -r1.99 -r1.100 src/sys/sys/namei.h
cvs rdiff -u -r1.43 -r1.44 src/sys/sys/namei.src
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
