Is Windows 10 memory compression used if you have no page file?

Solution 1:

Page file needs to be enabled for memory compression to be enabled. I've just verified it on Windows 10 version 1809.

I'm normally running this system with page file turned off, and despite enabling memory compression in MMAgent, checking the SysMain service is running and all prefetch & readyboost settings are enabled in registry, Task manager always says "Memory compression is not enabled" and I've never seen "(Compressed)" memory statistic go above 0 MB in the memory tab in task manager.

After setting up a paging file of 16 MB (minimum allowed size), the tooltip in the Task manager tab now shows the expected "Compressed memory stores an estimated .... of data..." message.

What I've still not verified is how does the size of paging file affect the maximum allowed amount of compressed memory.

Another related note: Prefetch and ReadyBoost can be disabled using regedit. They do not affect the operation of memory compression. However, "SysMain" service (confusingly called readyboost in older Windows versions) must be enabled, otherwise memory compression will not be enabled.