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Date:      Tue, 6 Nov 2018 02:04:54 +0000
From:      RW <rwmaillists@googlemail.com>
To:        freebsd-hackers@freebsd.org
Subject:   Re: Sudden grow of memory in "Laundry" state
Message-ID:  <20181106020454.1200f69c@gumby.homeunix.com>
In-Reply-To: <3F9246AC-0CBA-4C73-A39E-A1F6149BA079@yahoo.com>
References:  <ce38cbfa-e1c5-776e-ef2e-2b867c9a520f@gmail.com> <20180911150849.GD92634@raichu> <104be96a-c16b-7e7c-7d0d-00338ab5a106@gmail.com> <20180928152550.GA3609@raichu> <e705099c-ea42-4985-1012-50e9fa11addd@gmail.com> <20181024211237.302b72d9@gmail.com> <981C887D-78EB-46D2-AEE5-877E269AF066@yahoo.com> <c25e19a4-d3ef-e419-06f8-8a86082dbf31@gmail.com> <E4B508E7-04CC-41BD-934B-19EE69E85800@yahoo.com> <42f6544f-830c-18c5-e1a8-0acc4c3f09cc@gmail.com> <20181027043819.GX5335@kib.kiev.ua> <20181106012107.2898f093@gmail.com> <F68000D0-6037-48C0-85BE-D6BFF1934765@yahoo.com> <20181106005347.2f035e34@gumby.homeunix.com> <3F9246AC-0CBA-4C73-A39E-A1F6149BA079@yahoo.com>

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On Mon, 5 Nov 2018 17:30:42 -0800
Mark Millard wrote:

> On 2018-Nov-5, at 16:53, RW via freebsd-hackers <freebsd-hackers at
> freebsd.org> wrote:
> 

> >> Unfortunately, the wording of this message is a misnomer for what
> >> drives the kills: it is actually driven by being unable to gain
> >> more free memory but FreeBSD will not swap-out processes that stay
> >> runnable (or are running), only ones that are waiting.  
> > 
> > When you say it wont swap-out processes, do you mean that
> > literally, or do you mean it wont page-out from runable processes?
> > Swapping processes shouldn't be an essential part of recovering
> > memory, Linux doesn't even support it.  
> 
> Paging is a different issue as I understand. Without paging,
> no process could have a memory area bigger than RAM.

Modern VM manages memory at the page level, and paging replaced true
process swapping a long time ago. 

In FreeBSD a form of swapping was recreated on top of paging. Under low
memory conditions the recovery of memory from whole processes is
accelerated allowing more memory into the running/runable processes.
This is a relatively minor tweak to ordinary paging - AFAIK it shouldn't
prevent normal memory management at the page level.



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