RAM upgrade benefits

[ComSimPilot 623]

Hi all,

I want to share with you an observation that I made today after upgrading my DDR4 RAM memory from 16 GB to 32 GB. I had gathered some money that I wanted to invest to either purchase more RAM or a 2TB SSD dedicated to scenery. Currently I have my large scenery data in a 6 TB SSD drive (ORBX, XP11 Custom Scenery, Mesh, etc.) loading through symbolic links. 

Searching a lot and reading in many forums, including this one, I got mixed impressions. I would say that most people suggested that 16GB is certainly enough memory and there is zero benefits from upgrading to 32GB if the RAM consumption seen in Task Manager is lower than 16GB. There was a few others, especially in the DCS and XP forums that insisted that 32GB resulted in smoother experience and that the sim will use more physical memory if it is available. 

I chose to trust the later, and instead of buying an SSD, I upgraded my RAM to 32 GB (G.Skill. 3600Mhz CL16). Just loading the simulator in both XP and P3D, I instantly saw the benefits:

First, I loaded XP11, ORBX TrueEarth GB South at Heathrow airport. The RAM consumption was 21 GB. Panning around was smooth, no stutters or loading textures. Here, the need for 32GB was obvious, the simulator used the available physical memory while before it will top up to around 12-13 GB, making you think 16 GB is enough.

Then, I loaded P3D, ORBX TrueEarth Southamtpon with the A2A C172. I instaltly noticed that texture loading was much much faster. Selecting a plane in the Select Aircraft menu, resulted in an instant appearance of the rotating aircraft with all its textures. Before I would have to wait 2-3 seconds for the black plane to get it textures while rotating in the menu window. When I clicked to load the plane, it was also instantly loaded, no waiting. In the simulation, I can now pan around fast without seeing black textures in the distance, resulting in no stutters. All these observations was performed at the gate, no flying done yet. However, I could clearly see that all textures was now loading super fast compared to having 16 GB of RAM. When I opened the Task Manager I saw that 13.1 GB of RAM was used which would make you think that 32 GB was not utilized, however if you look more closely you can see how much of the RAM is actually cached at the same time. 18 GB of RAM was allocated as a  standby memory, storing data that is not currently used but can be available for fast loading. This results in these data being much faster available to load than if they were stored in a physical memory drive. Loading these files from a SATA connected SSD cannot be as fast.

So, to sum up, to me upgrading to 32 GB was the right move. I still get some big loading times especially with the current 6% bug of P3D, however the fact that all of the standby memory can be stored in RAM instead of the Windows page file, seems to do a huge difference. I would definitely recommend if someone can afford this upgrade, especially if you use heavy scenery scenarios. 

 

Edited April 8, 2019 by Daedalus

[martin-w 3,234]

Interesting post. Thanks!

[ZLA Steve 370]

Thanks for posting this write up.

Would you please report back your findings with respect to autogen loading in the distance after flying for 45 minutes or longer?

[ComSimPilot 623]

1 hour ago, ZLA Steve said:

Thanks for posting this write up.

Would you please report back your findings with respect to autogen loading in the distance after flying for 45 minutes or longer?

Yes of course. I'm not sure when I'll find time the next days to fly, but certainly I'll report my impressions after a full flight.

[jabloomf1230 2,445]

Windows uses its page file to store binary images of any lightly used background services (all those svchost,.exe files listed in the Task Manager). If physical RAM is available, it is used instead of the page file. You can check this out by using an alternative task manager like Process Explorer.  Any service that has been cached will show some enormous virtual size like 2 TB+. Swapping these services from cached RAM is much faster than swapping them from the page file, even if the page file is on a fast SSD.

I'm surprised that adding RAM makes that much of a difference in program launch times, but Windows in full of mysteries.

[Luke 782]

4 hours ago, jabloomf1230 said:

Windows uses its page file to store binary images of any lightly used background services (all those svchost,.exe files listed in the Task Manager). If physical RAM is available, it is used instead of the page file.

Executable code images are never stored in the page file; it has the disk image to restore from if the page(s) are swapped out from physical memory.

Cheers!

[SteveW 1,792]

More memory contributes to faster load times because the simulator can use more memory during the process of assembling the scene. Tests of loading require the understanding of the nature of the application, whereby an application like P3D loading up is not just about reading files. A good idea is to time the cold boot and load, compare also the loading up of a second and third time.

[SteveW 1,792]

Incidentally; the performance of loading can be intensified with hyperthreading since tasks loading the scene are split over more logical processors which maximises the throughput on cores with loading tasks on each LP. The problem of enabling HT with P3D is that it will also use the sister LP of the first core for the second task which draws throughput away from the main task. For that we can use an '01' in the AM to avoid the second task on the sister LP. The AM can contain '11' to be used where background tasks can be paired on sister LPs which are loading up the scene. These loading tasks can be seen to reach or get near to 100% on an LP during the scenario loading. An effective setup with HT is possible to maximise loading performance without detriment to simulator performance. The performance of loading up the scenario goes a long way to demonstrate the power of the system with respect to the settings chosen, since it is the biggest 'hit' the sim gets during operation usually. The fps based on amount of things to have to render per frame, while performance is about smoothly loading up the scenery ahead of time and interfacing with the rendering task without too much strain on it at the same time. Doing that requires not too many cores, rather than any amount, and care to ensure the rendering task is free to consume the entire core and sit in an environment not overloaded by other constraints like over-sized textures and over-set features, for the bandwidth of the system. Those situations don't play well with the sim, and failure to adhere to a responsible setup result in unfortunate conflicting results, leading to HT and AMs getting a bad name.

A point very well worth considering, especially when we may not see the expected results or changes in performance and load times with respect to memory sizes, core-counts, and sensible hyperthreading setup.

Edited April 9, 2019 by SteveW

[SteveW 1,792]

3 hours ago, Luke said:

Executable code images are never stored in the page file; it has the disk image to restore from if the page(s) are swapped out from physical memory.

Cheers!

Yes. The result is improved in the cache where Windows buffer granularity is 4kb. The cache being improved with more available memory.

[ryanbatc 12,797]

Interesting.  I found the same for XP11 when I went from 8GB to 16GB, even though the ram speed was slower.  I too use large scenery (ortho zl16 and some 18 areas).  P3D I don't really notice a change but I think my CPU is holding me back with that software.