How useful is compressed memory?


cereberus

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One of the features of Windows 10/11 is compressed memory.

Originally, when a pc needed more memory than it has available, it offloaded less used information in RAM temporarily to a hard drive.

With Windows 10, compressed memory was introduced whereby less used information was compressed, freeing up RAM. If more RAM is still needed, that gets offloaded to a hard drive as well. If RAM requirement is reduced, and pc needs access to data in compressed memory, it is automatically decompressed.

Even though it adds a slight performance reduction compressing and uncompressing, it far offsets the performance reduction using pagefilling as drives (even nvme) are much slower than RAM.

All fine in theory but how does it work in practice?

I created a virtual machine in Hyper-V and tested it with 10, 8, 6 and 4 GB (fixed) Ram allocated. I used Windows 11.

At 10 GB, no compressed memory is allocated. I opened 10 Edge tabs - no impact.

Same for 8 GB RAM

With 6 GB RAM, initially no compressed memory was allocated but some was allocated once I opened 10 Edge tabs

With only 4 GB RAM, some compressed memory was allocated from the start.

None of this is really unexpected but it does show, in part, why Windows 10/11 still runs quite well with only 4 GB RAM.

The above tests will vary for each users, and what they run. However, directionally, at least 8 GB RAM is really a good "entry level" and I would not recommend buying devices with only 4 GB (you can't really buy 6 GB RAM pcs as a rule, not without using two RAM slots e.g. 4+2).

Now we see how it works, but how useful is it?

In the end, compressed memory only frees so much RAM, and I tried tests (not that succesfully) to reach a point where I was compressing memory but was not actually needing pagefiling.

What I found was that it seemed when you needed extra RAM, it was usually at a level beyond compressed memory's usefulness and everything pagefiled anyway.

So, it seems to me compressed memory is only really of use if you need a little bit of extra RAM but not if you need a lot.

In the end, more RAM is better. As I said 8 GB is a good "entry level" for new users, but 16 GB is a more comfortable level for more experienced users multitasking a lot.

32GB or more is really only needed for memory hungry apps (games?) and users who run multiple virtual machines.

Although I asked how useful is compressed memory, it does provide some benefit but, perhaps, not as much as people might think.
It is possible to turn it off using powershell, but generally seems a bit pointless although some people have had stuttering issues (for example) with it on.

Fortunately Windows 10/11 is clever enough to decide when it is needed.
 

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