[QUOTE=kriesel;629575]I have found on a 24GB system that allowing 18GB in s2 is too much; 17 is stable, for ordinary wavefront exponents, but still gets slow/paging with 100Mdigit & above. Allowing all but 2.5GB as you appear to be is I think MUCH too aggressive. Try 10 of 16. Or 9.5. And/or be ruthless about exiting everything else. CPU will necessarily be rather idle while waiting for paging out/in of some of the prime95 stage 2 data that does not all fit in available ram.[/QUOTE]

A paging (swap) file can be a real bottleneck, especially with a mechanical drive. I literally roasted a drive a decade ago while doing video processing. I had to use an oven mitt to take it out after it died. It was that hot.

I have had [I]Prime95[/I], latest version, behave strangely with a fractional about of RAM allocated, such as 7.5GB. It would run really slow in Stage 2 of a P-1. 8GB was fine. I tried 9 and 10. This didn't leave W10 much wiggling room, but it ran alright. I plan on upgrading the RAM in this system soon. I will end up with either 32GB, or 40GB if I can leave two of the 4GB sticks in.

Perhaps a good rule-of-thumb would be to never try to use more than two-thirds of what is free, not what is installed. Windows 10 overhead uses about 3GB. This drops me from 16GB to 13GB available. Using 8GB for [I]Prime95[/I] is right around 60% of the available.

All of my Windows systems are used to the maximum RAM without an problem. Usually not more than 0.5GB free. Works fine.

I don't have a swap file. Swap files are dumb, IMO. Maybe Windows has some weird logic and likes to populate the swap file too aggressively? IDK. I suggest to disable and delete the swap file. It is only harming you and not helping. If you run out of RAM then buy more RAM.

I don't like them either, on modern PCs they're quite pointless. But unfortunately, some versions of Windows (and of Un*x) may or do take the existence of a swap file for granted and fail to behave properly without one. XP is absolutely fine without one, but newer versions may become unstable if you come anywhere close to depleting RAM, so I'd be reluctant even if there's a slight performance improvement, as losing data is so much worse.

I can't understand how every educated Windows user can not see that _everything_ has gone downhill since XP - usability, reliability, general sanity.

[QUOTE=Andrew Usher;629653]... [b]some[/b] versions of Windows (and of Un*x) may or do take the existence of a swap file for granted and fail to behave properly without one.[/QUOTE]Vague. Which versions? Which "Un*x"? I've never seen any OS "take the existence of a swap file for granted".

[size=1]What is "Un*x" anyway? Unax, Unex, Unix, Unox, Unux?[/size]

[QUOTE=Andrew Usher;629653]...But unfortunately, some versions of Windows (and of Un*x) may or do take the existence of a swap file for granted and fail to behave properly without one...[/QUOTE]

As an experiment, yesterday evening I changed my W10 setup to not have a swap file. It restarted fine, but it had 2GB less free RAM space after it all loaded. So, I put it back in the general vicinity of what size it appeared to be. In my case, W10 appears to store trivial things in it, whatever they may be. It is hard to tell if an SSD drive is thrashing as they read/write so rapidly, which is what mine is.

The only thing I run that might use it would be [I]Prime95[/I] running P-1's.

I am fairly certain that [I]Ubuntu[/I] created a swap area when I installed it on my Xeon system. How large, I have no idea.

[QUOTE=retina;629665][size=1]What is "Un*x" anyway? Unax, Unex, Unix, Unox, Unux?[/size][/QUOTE]
[SIZE="1"]That definitely must be a Regex: Ux, Unx, Unnx, Unnnx, ...

Edit: Unox is a manufacturer of concetrated soups in Germany. We love their Ochsenschwanzsuppe.[/SIZE]

Linux is fine without a swap file, until you fill RAM and hell may or may not break loose. Performing better under memory pressure is being patched in over time.

[url]https://www.phoronix.com/news/Linux-Does-Bad-Low-RAM[/url]

[url]https://www.phoronix.com/news/Meta-Transparent-TMO[/url]

[url]https://www.phoronix.com/news/Linux-6.1-PSI[/url]

[QUOTE=M344587487;629782]Linux is fine without a swap file, until you fill RAM and hell may or may not break loose.[/QUOTE]It is the same behaviour with a swap, it is maybe delayed for a few minutes instead.

Linux handles memory allocations badly. The [i]correct[/i] method for handling low memory is to simply deny excess allocations, and let the application figure it out when it doesn't get what is asks for. But sadly, Linux will gladly [url=https://mersenneforum.org/showthread.php?p=588922#post588922]greatly over-subscribe[/url] RAM, and then panic when an app actually tries to use it. :sad: I wish it was better.

[QUOTE=retina;629785]Linux will gladly [url=https://mersenneforum.org/showthread.php?p=588922#post588922]greatly over-subscribe[/url] RAM[/QUOTE]

You can [url=https://sysctl-explorer.net/vm/overcommit_memory/]tune that behaviour[/url]. It's enabled by default because some programs allocate way more memory than they actually use.

[QUOTE=Mark Rose;629854]You can [url=https://sysctl-explorer.net/vm/overcommit_memory/]tune that behaviour[/url]. It's enabled by default because some programs allocate way more memory than they actually use.[/QUOTE]I never knew that existed. :tu:

How can changes be made persistent? Isn't the /proc stuff volatile?

[QUOTE=retina;629857]I never knew that existed. :tu:

How can changes be made persistent? Isn't the /proc stuff volatile?[/QUOTE]

You could always set it in your .bashrc