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---------- Forwarded message ----------
From: Philip Guenther <guent...@gmail.com>
Date: Sat, Apr 14, 2018 at 11:13 PM
Subject: Re: swapctl question
To: Z Ero <zerotetrat...@gmail.com>

On Sat, Apr 14, 2018 at 10:37 PM, Z Ero <zerotetrat...@gmail.com> wrote:

> amd64, 6.2
> I have my swap partition set to priority 9 in fstab.

> Why does swapctl report priority 0?

The compiled in default swap location (normally the 'b' partition of the
boot disk) is added as swap at priority zero in kernel startup as part of
uvm_swap_init(), before any userspace processes are started or /etc/fstab
is read.

# swapctl
> Device      512-blocks     Used    Avail Capacity  Priority
> /dev/sd0b     11874624  1266232 10608392    11%    0
> # cat /etc/fstab

You only have one swap device so the priority doesn't matter: priority is
for selection _among_ swap devices and has no effect on the kernel's
decision of _whether_ to swap out a page.

I want to minimize swapping since I am using a mechanical hard disk
> and thus swap slows things down.

Slows things down relative to _what_?  Which statistics have you been
examining when under the workload you're interested in?

Philip Guenther

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