[linuxnow]

The daemon's share of an own LV2 add on the Pi (job 11, add cut a). Strace of three own adds of ZamComp on the real world showed, per add:

• up to three walks of the LV2 path's manifests, in directory order: about 1.4 ms for a plugin found early, much more for one found late (gx_reverb's own add 96 ms against about 72 for the others);
• a listing of the qualification directory (3664 files) and a JSON parse of the plugin's records: about 3 ms.

Now a bundle that holds the plugin's binary is remembered and checked with its one manifest on each lookup. A bundle that moved or no longer holds the plugin is walked for again. A bundle that only names the plugin (a GUI bundle) is never remembered, so a binary installed later still wins. Records are remembered with the directory's time and each file's time and size.

Red first, locally in the worker image: test-proc failed 'found again with one manifest read' (1 failed), qualcost-test failed 'a repeat read lists and parses once' (1 of 14). Both are green with the change.

Sabotage, each guard broken alone:

• the memo's manifest check removed: 3 proc checks red (moved bundle, bundle no longer naming the plugin, read count);
• the record file-time check removed: 'rewritten in place' red;
• the directory-time check removed: 'a record added' red.

Pi before/after numbers follow in a comment. Console gain: the console's daemon adds LV2 plugins through the same lookup, and its scene loads add many at once.

[linuxnow]

Pi 5, Zynthian vangelis, real LV2 world (1336 plugins), private dummy JACK server at 48000/256. Own LV2 adds through the daemon: a fresh daemon per run, four adds (the first, then three more), three runs, medians in ms. Installed 0.15.7 against this branch built on the Pi.

plugin	0.15.7 first	0.15.7 next	this branch first	this branch next
ZamComp	53	69	53	59
ZamEQ2	53	69	53	59
MVerb	62	75	58	64
Invada compressor stereo	64	75	58	64
x42 fil4 stereo (found late in the walk)	78	91	70	59

On 0.15.7 the later adds cost more than the first: from the second add the daemon also lists the qualification directory and parses the records. That is gone, and a plugin found late in the walk no longer pays the walk on each add.