Re: how to recycle Inact memory more aggressively?

On Sun, 13 Mar 2016 16:41:17 +0100
Fabian Keil <freebsd-listen_at_fabiankeil.de> wrote:

> Gary Jennejohn <gljennjohn_at_gmail.com> wrote:
> 
> > In the course of the last year or so the behavior of the vm system
> > has changed in regard to how aggressively Inact memory is recycled.
> > 
> > My box has 8GB of memory.  At the moment I'm copying 100s of gigabytes
> > from one file system to another one.
> > 
> > Looking at top I observe that there are about 6GB of Inact memory.
> > This value hardly changes.  Instead of aggressively recycling the
> > Inact memory the vm now seems to prefer to swap.  
> 
> Are you using ZFS?
> 

No, only UFS, so it's not due to pressure caused by ZFS.

> > Last year, can't rmember excatly when, the behavior was totally
> > different.  The vm very aggessively recycled Inact memory and,
> > even when copying 100s of GB of files, the system hardly swapped.
> > 
> > It seems rather strange to me that the vm happily allows gigbytes
> > of Inact memory to be present and prefers swapping to recyclincg.
> >
> > Are there any sysctl's I can set to get the old behavior back?  
> 
> I don't think so.
> 
> I'm currently using this patch set to work around the issue:
> https://www.fabiankeil.de/sourcecode/electrobsd/vm-limit-inactive-memory-more-aggressively.diff
> 
> Patch 4 adds a couple of sysctls that can be used to let the ZFS
> ARC indirectly put pressure on the inactive memory until a given
> target is reached.
> 

Thanks, I'll take a closer look at it.

-- 
Gary Jennejohn