Re: Unable to use compressed swap, 10.9.5

On 2018-07-17, at 9:30 AM, Michael <[email protected]> wrote:

> I'd like some help figuring this out. My machine cannot use compressed swap in 10.9.5.
> 
> This is not an "always" issue. Originally it did use compressed swap with no problem.

So I found the first issue, and I don't understand it. I'm looking for more help.

I had, probably by mistake, configured a boot plist at /Library/Preferences/SystemConfiguration. I thought that the values I specified in the boot-args nvram setting were running things, but no, that file was overriding anything I was trying to specify on the boot-args.

So that's issue number one. I can make compressed swap "work" by removing this line:
	<string>vm_compression_limit=1048576</string>

But that's the problem. The default action is to use 10 GB of my 16 GB for compressed swap. That's too much.

The vm compressor code is located at https://opensource.apple.com/source/xnu/xnu-2422.1.72/osfmk/vm/vm_compressor.c.auto.html
Reading it (and it was in my browser history, as well as a question I asked on stack overflow), the vm_compression_limit seems to go into a maximum number of compressed pages limit.

The number in the config file is 1024 * 1024, which seems to be a reasonable number of pages (1m pages, 4K per page, is 4 GB.) Yet it causes a swap error as soon as the limit is reached, and I'm prompted to close an unwanted app because the system is "out of application memory".

So I've got two choices, and I'm looking for the third:
1. No compression -- system works, but swap fills up rather quickly.
2. Compression, default -- system "works", but I don't have enough live memory.
3. What I want -- compression with less memory used by the compressor.

Can anyone help with this?