Re: [PLUG] swappiness and ssd

["Gavin W. Burris" <bug@wharton.upenn.edu>]

Is 0 really sane?  It was my understanding that swappiness=0 was too
aggressive, almost disables swap all-together.  Setting swappiness=1 may
be better, only swapping to avoid the OOM.  This, and keeping just a few
gigs of swap as a last-ditch protection, provides a metric to monitor
and avoid.

Big fat warning here, on the Performance Tuning Guide: 
https://access.redhat.com/documentation/en-US/Red_Hat_Enterprise_Linux/7/html/Performance_Tuning_Guide/sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-Memory-Configuration_tools.html#sect-Red_Hat_Enterprise_Linux-Performance_Tuning_Guide-Configuration_tools-Configuring_system_memory_capacity

Cheers.


On Fri 07/10/15 09:24PM -0400, Rich Mingin (PLUG) wrote:
> Not at all. It's the default I had recommended to me by the Arch wiki, some
> knowledgeable friends, and I think also Rich Prime. It works for me, though
> I still have an issue where VMware stalls my whole machine for 5-30 seconds
> every 3-5 minutes if I don't manually disable khugepaged defrag. Ah well.
> 
> On Fri, Jul 10, 2015 at 9:10 PM, Keith C. Perry <kperry@daotechnologies.com>
> wrote:
> 
> > Ahh so swappiness=0 is not a weird setting.
> >
> > ---
> > KP-
> >
> > On Jul 10, 2015 9:05 PM, "Rich Mingin (PLUG)" <plug@frags.us> wrote:
> > >
> > > I was declining to post, but I'll just chime in, I'm also swappiness=0
> > on my machines. The two that touch VMs have 32GB of ram, SSDs, and a small
> > swap file on some spinning rust, so I get all of the benefits listed,
> > without unneeded SSD wear.
> > >
> > > On Fri, Jul 10, 2015 at 8:46 PM, Rich Freeman <r-plug@thefreemanclan.net>
> > wrote:
> > >>
> > >> On Fri, Jul 10, 2015 at 6:31 PM, Keith C. Perry
> > >> <kperry@daotechnologies.com> wrote:
> > >> >
> > >> > Rich Freeman, you and I both leave off for similar reasons.  Did you
> > know
> > >> > about this?  Looks like a lower setting (like 0  LOL) might get swap
> > to
> > >> > perform in a "sane" way.
> > >> >
> > >>
> > >> I've never really been satisfied with it, even with a swappiness of 0.
> > >>
> > >> --
> > >> Rich
> > >>
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-- 
Gavin W. Burris
Senior Project Leader for Research Computing
The Wharton School
University of Pennsylvania
___________________________________________________________________________
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