[DragonFlyBSD - Bug #2375] (Resolved) Wishlist: tmpfs directory lookup optimization

Francois Tigeot via Redmine bugtracker-admin at leaf.dragonflybsd.org
Mon Jun 18 11:02:49 PDT 2012

Issue #2375 has been updated by Francois Tigeot.

Status changed from New to Resolved
% Done changed from 0 to 100

Pushed in commit 29ca4fd6da8bb70ae90d8e73ea3c47fda22491a7
Bug #2375: Wishlist: tmpfs directory lookup optimization

Author: Venkatesh Srinivas
Status: Resolved
Priority: Normal
Target version: 

tmpfs directories are structured as lists of directory entries; this leads to linear lookup costs. Directories with many files become fairly expensive to operate on.

http://leaf.dragonflybsd.org/~vsrinivas/tmpfs5.diff is a patch that introduces a 64-wide hash table (of lists) to speed up lookups. The patch is currently littered with debugging cruft and could benefit from cleaning.

http://leaf.dragonflybsd.org/~hofmann/tmpfs_rbtree.diff is a cleaner patch that uses an RB-tree, keyed on the name of the file in question.

Both approaches are solid improvements over the current lists, but could use some testing (benchmarking) to determine which is worth applying. The hash list patch has had many hours of fsstress testing; it now works well. The tree patches at the same points.

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