K 10
svn:author
V 3
mjg
K 8
svn:date
V 27
2017-12-31T04:06:11.190743Z
K 7
svn:log
V 2317
MFC r323307,r323308,r323385,r324378,r325266,r325268,r325433,r325451,r325456,
    r325458:

    namecache: factor out dot lookup into a dedicated function

    The intent is to move uncommon cases out of the way.

=============

    namecache: fold the unlock label into the only consumer

    No functional changes.

=============

    namecache: clean up struct namecache_ts handling

    namecache_ts differs from mere namecache by few fields placed mid struct.
    The access to the last element (the name) is thus special-cased.

    The standard solution is to put new fields at the very beginning anad
    embedd the original struct. The pointer shuffled around points to the
    embedded part. If needed, access to new fields can be gained through
    __containerof.

=============

    namecache: factor out ~MAKEENTRY lookups from the common path

    Lookups of the sort are rare compared to regular ones and succesfull ones
    result in removing entries from the cache.

    In the current code buckets are rlocked and a trylock dance is performed,
    which can fail and cause a restart. Fixing it will require a little bit
    of surgery and in order to keep the code maintaineable the 2 cases have
    to split.

=============

    namecache: ncnegfactor 16 -> 12

    It is used on each new entry addition to decide whether to whack an existing
    negative entry in order to prevent a blow out in size, but the parameter was
    set years ago and never revisited.

    Building with poudriere results in about 400 evictions per second which
    unnecessarily grab entries from the hot list.

    With the new parameter there are next to no evictions of the sort.

=============

    namecache: fix .. check broken after r324378

=============

    namecache: skip locking in cache_purge_negative if there are no entries

=============

    namecache: skip locking in cache_lookup_nomakeentry if there is no entry

=============

    namecache: wlock buckets in cache_lookup_nomakeentry

    Since the case of an empty chain was already covered, it si very likely
    that the existing entry is matching. Skipping readlocking saves on lock
    upgrade.

=============

    namecache: bump numcache after dropping all locks

    This makes no difference correctness-wise, but shortens total hold time.

END