a very short argument for the rolling cache

[sightseer 895]

I've read a lot of people saying that they have very fast internet and so the rolling cache isn't needed.

This I don't believe is true.  It seems to me that pauses in the sim are largely data loading and you cannot guarantee that the MS server will be faster than your local hard drive no matter how fast your connection.  It also increases server load I would think which probably slows everything down for everyone.

I think we'd all be better off if everyone used the rolling cache as the program was designed.  Set up a large cache on a fast drive and fly a while and let it download some data for a while and see if things dont get better over time.  I think they will.

[loge 42]

Indeed.  The devs confirmed on one of the Q&As that the rolling cache is simply a cache of http responses, so it will only hit the cache if it would otherwise have made a request to the MS server.  Any SSD (even an SATA one) will be much faster than a fast internet connection; even an HDD will be faster in most cases.  In any case, I would be surprised if the MS servers are fast enough to use the full bandwidth of a fast internet connection.

Unless there is a bug in the rolling cache implementation - which I've not seen any evidence of - it makes no sense not to use it.  And as you say, the more people that use it, the less load on the MS servers, benefiting everyone's performance on a cache miss.

[MrFuzzy 2,117]

33 minutes ago, sightseer said:

I've read a lot of people saying that they have very fast internet and so the rolling cache isn't needed.

This I don't believe is true.  It seems to me that pauses in the sim are largely data loading and you cannot guarantee that the MS server will be faster than your local hard drive no matter how fast your connection.  It also increases server load I would think which probably slows everything down for everyone.

I think we'd all be better off if everyone used the rolling cache as the program was designed.  Set up a large cache on a fast drive and fly a while and let it download some data for a while and see if things dont get better over time.  I think they will.

The point is: how does rolling cache really work? I couldn't find official MS documentation. I turned it off last August because it caused a lot of stuttering and never bothered to check it again. It was on an NVME SSD.

I read many times that it is useful if you fly again in the same area before the cache content changes. But even in that case, if you flew at 30,000 ft and fly again at 3,000 ft, the cache content will be probably useless (lower resolution than you need). 

If the sim were smart and optimized, it would use spare bandwidth, CPU threads, VRAM and RAM in order to preload scenery in the background as much as possible. Instead, you can have stutters with 19 CPU threads at 20% occupation, 50 GB of RAM and 18 GB of VRAM free.

Manual cache may make more sense if you were able to pre-download the scenery according to your flight plan, not just a rectangular area.

[Nate1 163]

That would be great - integration with the MSFS flight planner which causes the route to cache (at the appropriate altitude/detail levels).

 

[bobcat999 8,440]

I will try the manual cache tonight for the Sedona area.  I haven't tried it for months. 

The area doesn't suffer from stutters / pauses, but the scenery / mountain morphing can be quite bad at times.
I wonder if it will prevent or reduce this?

Edited April 19, 2021 by bobcat999

[Axis3600 50]

42 minutes ago, Nate1 said:

That would be great - integration with the MSFS flight planner which causes the route to cache (at the appropriate altitude/detail levels).

I thought about it at a time too but I don't think it could be possible ... Well, it's the manual cache but it was buggy so I haven't tried it for months.

I will follow the process of trying the rolling cache anyway, even if I do not understand its operation or its usefulness ...

[sightseer 895]

1 hour ago, MrFuzzy said:

how does rolling cache really work?

I don't know how the rolling cache works.  I don't know how much of the sim works as far as downloading data for buildings and such.  How much data is downloaded as you fly?  Is it just aerial imagery and photogrametry data?  Does it include vector data and building data?  How about tree placement data?  Does it only include tree placement data in PG areas?

What I know is that PG areas greatly improve for me over time with a cache and that makes sense because my internet is not that fast.  I built a 100 GB cache when I first started using the sim and things just kept looking better and better (I fly in Florida a lot - Tampa and Orlando areas which are PG).  Then I was doing some experimenting and, in the process, deleted and reset my cache and now I am slowly rebuilding the scenery and as it does that I am getting considerable large pauses.  That made me realize that people who don't use the cache have assumed that MS will serve them data at a high rate which may not be true and they'd be in the same boat as I was with slower internet but instead of it being temporary as it is with me it would be permanent because they dont use a cache.

I just think its a good idea to run with a rolling cache as it was intended.  Data loading pauses are still going to occur - especially when Asobo updates data and cues everyones systems to redownload some portion of the data - if thats the way it actually works...  like updated water masks -- are all the updates downloaded to everyone at update time or are they only downloaded as people fly into those areas?  If its the latter then its likely that all vector data would be downloaded on the fly and any changes in that data would cause more pauses.

We can minimize pauses overall by using the cache.  Sure, when you first turn it on you still have to download as if it were off but , over time, it fills up with data and things get better.  And whose to say that data downloaded for one region doesnt get used in another somehow?  Maybe all my flying over Florida downloaded something that was useful when I went to Memphis or san Diego or San Fransisco.  I dont really know.  I dont think most of us do.

[cavaricooper 2,613]

Have we settled on an optimal size for the rolling cache?

[marsman2020 1,310]

In a Dev Q&A the devs stated that requests that would go out to the internet are checked against the cache first and if the data is present it is returned in the same format and it is the same data.

How that statement works in the context of some of the issues with scenery people have seen resolved by getting rid of it, idk.

[colklink14 24]

I have 2 2tb nve m.2 drives. One has only msfs202 the other is empty. I am going to put 100gb on the empty one and see how that flies (pun intended)

[Moria15 950]

how would this work if you have cached a default airport and then replaced it with a custom one or had a custom one and then updated the custom one?   I am just wondering how these requests determine the difference in the area from whats been seen before

Just a thought.. perhaps I will set up one and try it to see what happens.

Graham

[Ianrivaldosmith 5,317]

19 minutes ago, colklink14 said:

I have 2 2tb nve m.2 drives. One has only msfs202 the other is empty. I am going to put 100gb on the empty one and see how that flies (pun intended)

Tried that. Doesn’t make a difference. 

[Dazzlercee23 66]

12 minutes ago, Moria15 said:

how would this work if you have cached a default airport and then replaced it with a custom one or had a custom one and then updated the custom one?   I am just wondering how these requests determine the difference in the area from whats been seen before

Just a thought.. perhaps I will set up one and try it to see what happens.

Graham

Your airport is stored locally and will take priority. 

 

[MrFuzzy 2,117]

5 hours ago, sightseer said:

I've read a lot of people saying that they have very fast internet and so the rolling cache isn't needed.

This I don't believe is true.  It seems to me that pauses in the sim are largely data loading and you cannot guarantee that the MS server will be faster than your local hard drive no matter how fast your connection.  It also increases server load I would think which probably slows everything down for everyone.

I think we'd all be better off if everyone used the rolling cache as the program was designed.  Set up a large cache on a fast drive and fly a while and let it download some data for a while and see if things dont get better over time.  I think they will.

OK, I did a reproducible test with CapframeX:

• JFK landing challenge
• Started capturing just after having clicked on "Fly now"
• Never moved the view in the cockpit 
• Landed the 747 at the best of my skill (scored between 913000 and 939000 points with pretty much the same descent rate and path)
• Stopped capturing as soon as the score appeared on the runway

I expected the first run after enabling the rolling cache (32 GB on my fastest drive, a Samsung 970 EVO NVME SSD) to be the slowest, due to the extra work needed to write the data on the SSD drive. That was not the case but in my opinion the results are within experimental error.

I didn't notice any benefit in the 2nd run with the rolling cache containing the data I needed either. Still some stuttering approaching the runway, due to the skyscrapers on the background popping in and framerate tanking from 45-50 fps to 30-35, maintained while rolling on the ground.

 

[RaptyrOne 1,398]

Yep, that’s my experience too. Rolling cache simply does not provide any benefit and as such, is a hinderance. What’s the point of writing GB’s of data to your SSD when it does nothing? Asobo have yet to demonstrate how it works, or that it even does work. It stays off on my  PC until proven otherwise.