So interestingly enough I was looking at my swap from this convo, and surprisingly noticed that I'd never added any swap to this system!  I built the swap lvm slice, but never added it to the fstab, don't remember if on-purpose or not.  This system has 128gb of ram, so not that I notice really, but might explain why I might see some weird lagging at times.  I usually blame (crap) compositing...

I suppose I've been using this pc for a couple years now without swap, so it *is* doable (with a lot of ram), but I think I might enable it and see if things are any better with than without swap.

-mb

On Mon, Sep 24, 2018 at 9:46 AM Stephen Partington <cryptworks@gmail.com> wrote:
YEah, So I always consider installing at least a GB or two for swap and setting swappiness to 0 for that. It also might explain why Mr Butash still can see a difference in performance on what he does when swap is there or not.

On Mon, Sep 24, 2018 at 9:44 AM Carruth, Rusty <Rusty.Carruth@smartm.com> wrote:

Wow, that quote is very interesting. 

 

Thanks! 

 

(google found the reference for me.  One of them (possibly the original reference others are using) is https://www.kernel.org/doc/gorman/html/understand/understand014.html )

 

I read it, and it appears that the reference is talking primarily about what the kernel does.  I kept searching and couldn’t find any definitive statement that a PROGRAM could request this, however apparently some JVM somewhere can do something with memory that almost requires there be swap to keep the JVM from getting killed by the OOM monster…  er, killer… er, task.. er, whatever.

 

 

Rusty

 

From: PLUG-discuss [mailto:plug-discuss-bounces@lists.phxlinux.org] On Behalf Of Stephen Partington
Sent: Sunday, September 23, 2018 12:18 AM
To: Main PLUG discussion list
Subject: Re: To swap or not to swap ;-) (was RE: To lvm or not to lvm)

 

I have found some applications use swap with direct calls.

 

"A significant number of the pages referenced by a process early in its life may only be used for initialisation and then never used again. It is better to swap out those pages and create more disk buffers than leave them resident and unused." 

 

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--
A mouse trap, placed on top of your alarm clock, will prevent you from rolling over and going back to sleep after you hit the snooze button.

Stephen

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