on linux virtual memory manager (was: Re: disable akonadi)

René J.V. Bertin rjvbertin at gmail.com
Mon Sep 3 21:33:20 BST 2018

On Monday September 03 2018 20:16:17 Martin Steigerwald wrote:

> How would it know which application this would be when mutiple processes 
> allocate a chunk of memory each? If you have a bank and all people want 
> their money back at the same time, how would you decide who will not get 
> their money back?

First come, first served basis, and something similar for big requests, with some kind of floating threshold of what's still acceptable as a function of memory stress?

> The first time I learned about this behavior of the Linux kernel I 
> thought: WTF? AFAIR the Solaris kernel does not do that. I am not sure 
> what BSD kernels like the one of FreeBSD or DragonFly BSD do.

AFAIK the Linux kernel is the only one that has overcommit (at least such an extreme version).

> 2) Increase /proc/sys/vm/overcommit_ratio to maybe about 80 or 90 so 
> that the kernel allows to allocate 80 or 90% of the physical memory even 
> with overcommitting disabled completely.

I used to do
echo 80 > /proc/sys/vm/overcommit_ratio
echo 2 > /proc/sys/vm/overcommit_memory

> Enough of that. Just in case you like to get rid of baloo file indexer 
> you may like to enable strict overcommit. :)

I think there are easier ways to do that, like turning desktop search off in system-settings ;)


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