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Date:      Thu, 21 May 2015 10:51:55 -0500 (CDT)
From:      "Valeri Galtsev" <galtsev@kicp.uchicago.edu>
To:        "grarpamp" <grarpamp@gmail.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: End user RAM usage survey
Message-ID:  <43064.128.135.70.2.1432223515.squirrel@cosmo.uchicago.edu>
In-Reply-To: <CAD2Ti2_6Cjc6U_+WYyAhB7aQ1WHKpV0aqBjRSiaU_+RSJDkQmg@mail.gmail.com>
References:  <CAD2Ti2_6Cjc6U_+WYyAhB7aQ1WHKpV0aqBjRSiaU_+RSJDkQmg@mail.gmail.com>

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On Thu, May 21, 2015 4:41 am, grarpamp wrote:
> For those of you using end user class systems bought within the
> last few years (Intel: i3, i5, i7, E3; AMD: APU, FX) for things
> such as desktop, fileserver, multimedia, browsing, development,
> office, games, and VMs for the same... how much memory are you
> using? (including swap, excluding ZFS)

Majority of our FreeBSD machines are AMD Opterons (2 or 4 socket single to
16 core CPUs), they are servers mostly converted into such from retired
(re-purposed) number crunchers, so they usually have larger amounts of RAM
than they actually need. Anyway: RAM from 8GB to 64GB (the larger RAM
machines can host really many jails).

I also have a special note on swap. FreeBSD seems to want you badly to
have swap, so I do have swap of FreeBSD machines. However, I never make
swap larger than 4GB. If you come to the point you have to swap out some
memory pages to disk, then you definitely need extra RAM. Which is cheap,
just add RAM. I do respect FreeBDS's requiring me to have some swap. That
is the only reason I do have swap on FreeBSD machines. I run a bunch of
Linux number crunching machines with large amounts of RAM (16 GB - 512 GB
of RAM). I never had set any swap on these machines (running Linux, as you
may notice, I'm less respectful to what Linux usual recommendations are -
relying more on my own insight there). Just imagine that you need to swap
out to disk 4GB, and back from disk into RAM, and this you will have to do
any time you switch to and from some of the processes. Process switching
happens on the order of milliseconds. And each of the switching requiring
swapping will take as long ad disk read/write takes, which is many
seconds. The need of such swapping will just bring your box to its knees.

Just my $0.02

Valeri


++++++++++++++++++++++++++++++++++++++++
Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
++++++++++++++++++++++++++++++++++++++++



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