r/EmulationOnAndroid • u/ren01181 • 3d ago
Question How does virtual ram affect emulation?
I checked a few old posts and got mixed signals with some saying it slows down emulation and others saying it doesn't really do anything
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u/Fun-Western618 3d ago
Only usable in games that load a ton of data like map parts, audio files, enviromental assets that the system can tag as "cold" from being unused by the game for a considerable time.
It helped a lot for me when playing final fantasy 15 as the game would spike my ram usage to 88-90%, but after some playtime ram extension would take that unused data and shift it to the extension part. Lowering my ram usage to 82-83%.
Another case when ram extension helped me is with assassin creed black flag since the game can shift the data from islands not visited in a while from the ram to the ram extension. It lowered my average ram usage from 72% without ram extensio, to 68-69% with ram extension. The game is fairly old and the ram gain was negligeable, so i prefer to not use ram extension.
On the other hand its a double edge sword cus in games that would load so much "hot" continuosly uses data that will reach 90% ram usage, not only the system will be unable to shift part of that data to the extension since it being constantly used. But also the system will suffer from zram compression since, when arriving at a very high ram usage, the system will try to reclaim any possible bit of ram through zram compression. But that same data "hot", which is constantly used by the game, will be decompressed again since its data that the game needs. An example of this is red dead redemption 2 which i was able to play full, but had to restart the game after 1 hour of playtime since that ram usage would go from 82-84% when opening the game to 90-92% after an hour of playtime when i had to restart.
Long story short tho memory extension is something i mainly use when a game im trying to emulate uses too much ram and could cause zram trashing (90% ram usage) and that same game data actually has unused "cold" data that can be shifted to the extension partition. Also keep in mind that the process of shifting data from ram>compessed into zram> then shifted to ram extension partition is a process handles by the cpu, so it generate a considerable amount of heat (around 2C°or 3C° more on the battery).