improve fastforward performance

murkland / tango-legacy

last generation rollback netplay for mega man battle network / 前世代のロックマンエグゼのロールバックネットプレイ

GNU Affero General Public License v3.0

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Open bigfarts opened 2 years ago

bigfarts commented 2 years ago

not sure why: i had thought this was a fastforwarder issue but simply not setting the dirtyState will also exhibit this issue.

also strangely enough the fastforwarder will always cause a skip of 1 frame but fixing this behavior will actually break everything

bigfarts commented 2 years ago

latency is in the fastforwarder: at high delay, fastforwarder can miss the 16ms input window and cause stuttering

bigfarts commented 2 years ago

testing on my local computer, i can get ~2000fps in the fastforwarder, which sounds like a big number, but it's not:

that's like 0.57ms per frame
at 400ms ping we expect around 13 frames of delay so that's like 7ms taken up by fastforwarding
if each frame needs to get out in 16.6ms that's already like 42% of the available time slice
2000 / 60 is ~33 frames per frame i guess on my machine at least, assuming zero overhead

bigfarts commented 2 years ago

shitty benchmark:

without beef trap (33 frames per frame):

2022/04/03 01:08:32 time taken for 1000 frames: 502.435958ms

with beef trap (28 frames per frame):

2022/04/03 01:09:47 time taken for 1000 frames: 588.009583ms

a somewhat significant difference of 15%