Very slow directory read performance with VFS layer. about phlegyas HOT 5 CLOSED

Profiled with VisualVM. Looks like I'm hitting this: https://stackoverflow.com/questions/40538780/performance-problems-with-clojure-hashmaps-lookup

Surprising to see hashmap lookups be so slow. I'll try and keywordize all the appropriate keys and see if it helps.

from phlegyas.

Packing with mapcat also looks like a bottleneck and candidate for optimisation.

from phlegyas.

I've added some profiling code, and it looks like assembly/disassembly routines are unacceptably slow.

from phlegyas.

Refactored the frame assembly/disassembly routines somewhat in f28e41e.

from phlegyas.

Damn. After days of investigating... https://comp.os.plan9.narkive.com/qHFL5oFa/speed-of-9pfuse-on-linux

(time (count (keys (read-dir-contents conn 1))))
"Elapsed time: 68.941502 msecs"
503

I think I can close this as NOTABUG. At least for now, performance of directory reads is not ridiculous, and it looks as though the overhead is almost entirely caused by the OS VFS layer and dodgy client implementation.

from phlegyas.