johan torp f910700701 Memory-optimized custom IOStore hash map - 65.7 -> 25.9MB for internal project on Gen5 console ...

Exploits that the map is large (~1M) and rarely modified

Memory saved by:
* TMap saves slot and next-in-slot using 8B / item. FPackageIdMap is built once presorted, next-in-slot is next item. Only use 1bit / item to mark slot end.
* Only store 3/4 of FPackageId key - 1/4 is implicit by slot, which requires min 128K capacity
* Up to 400% load factor using 4-stage lookup, slot -> 2B hash -> 4B hash -> value. 2B array fits 32 items / 64B cache line, enabling a high load factor with little perf loss
* More compact entry handle and entry memory layout
* Deduplicating some entries
* Carefully storing entry data so container ownership is inferable from offset allows dropping 7.5MB of FIoContainerHeader::PackageIds and non-deduped StoreEntries

Surprisingly lookup got >4.5x faster too, despite 4 memory indirections instead of 2. Lookup can be optimized further by vectorizing. Rebuilding the map is also faster.

#rb pj.kack

[CL 29906389 by johan torp in ue5-main branch]

2023-11-23 03:17:18 -05:00

..

Internal

…

Private

Memory-optimized custom IOStore hash map - 65.7 -> 25.9MB for internal project on Gen5 console

2023-11-23 03:17:18 -05:00

Public

GFP state machine can now detect when its possible to force monolithic shader library loading which is faster if we know we don't need to search for chunked shader libraries.

2023-09-20 15:11:58 -04:00

PakFile.Build.cs

AutoRTFM some missing modules

2023-10-16 13:03:05 -04:00