![]() It provides memory compressor with swapping disabled. Mode 0x2, VM_PAGER_COMPRESSOR_NO_SWAP, is the best choice here. Modes 0x8, 0x10 and 0x20 are the so-called “freezer” modes, which “freeze” the OS instantly when memory is under pressure. Mode 0x1, VM_PAGER_DEFAULT, turns off memory compressor and swapping, which is proved to be harmful to the system stability. Set these variables via an nvram command: Then you might control the vm compression: $ sysctl -a vm.compressor_mode Please let us know if you find a setting that works for you and don’t down vote other people if they suggest things - this is how we all learn by hashing out engineering and software challenges - even against odds of it not working in the end.įirst and best line of defence would be to kill processes or services not needed. ![]() I do encourage everyone to try these things - especially if you have desire to know the internals of an operating system, but the premise here that VM needs to change doesn’t seem to ring true based on the details provided or the long experience of attempting this in the past. Then you’ll have the best memory turning for the actual OS and the virtual software (VMWare Fusion is my general first recommendation, but check out Parallels or even some free options if you have time and inclination) so you can put the code that needs an iron fist governing virtual memory on Linux and let the mac apps be mac apps.Īnd just to go out on a limb, in the seventeen years since OS X shipped, I’ve worked with dozens of people that went down the path you propose - find a case where virtual memory signals a problem and then change VM to overcome those software needs, in every case, we ended up fixing the applications or fixing where we run things instead of finding a magic setting or mortification that didn’t cause more harm than good. Now - you might have a super good reason why you’re asking to alter the virtual memory, but macOS micro kernel isn’t designed for the level of tweaking that Linux is and if you truly need to manage VM that tightly, I would encourage you to either locate that code on a separate server via putting it in the cloud, on a second local device or even virtualizing Linux guest OS on top of macOS. Any change you make to the algorithm will still break if you have software that’s not allocating memory correctly, so this problem probably needs to return to isolate and identify what is causing the memory pressure so that compression and swap become a symptom of the underlying issue. I say this with kindness, but no, no, no.ĭon’t change the fundamental design and process of virtual memory management of macOS because you have a system or workload that leaks so badly that you have accumulating swap piling up and the algorithm breaks down. Apple Engineering claim it 'works as designed'. This definitely has a performance impact. I used to think there must be something I was installing or doing wrong, but on brand new Macs at work with nothing extra installed, consuming RAM via opening lots of tabs in Safari will soon enough show use of swap space despite lots of free RAM.Īnd yes, it lags - badly at times. It's utterly absurd and indefensibly broken. The gibberish "memory pressure" colour is green, whatever that means. Right now, after a wake-up the machine has 11GB free, 5GB in use and 6GB swapped. On my home laptop, sleep cycles make it even worse. ![]() I agree with this Mojave does not, compressing data and swapping it to disc even when gigabytes of free memory are present. I've been told many times by very confident posters on sites such as this that free memory is a bad idea, because it's sitting there consuming power and being of no other use. Since the SSDs in modern Macs are soldered onto the main board, the situation is dire. On an SSD, every write causes wear & tear to the hardware, so this is actually (albeit in a small way) physically damaging behaviour. It's made even worse under Mojave, where free memory - not even disk cache, but completely free - is present, but the system decides to use swap anyway. shrinking the cached files area) has been a problem for years. ![]() Unnecessary swapping in the face of other options (e.g. I have the same issue and completely sympathise.
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