Re: Strange ARC/Swap/CPU on yesterday's -CURRENT

From: Mark Millard <marklmi26-fbsd_at_yahoo.com>
Date: Sat, 17 Mar 2018 09:51:31 -0700
On 2018-Mar-17, at 2:38 AM, O. Hartmann <ohartmann at walstatt.org> wrote:

. . .

> last pid: 16958;  load averages:  0.10,  0.21,
> 0.16
> up 6+08:57:07  10:34:01 19 processes:  1 running, 18 sleeping CPU:  0.3% user,  0.0%
> nice,  0.5% system,  0.0% interrupt, 99.2% idle Mem: 27M Active, 1504K Inact, 96M
> Laundry, 188M Wired, 1900K Buf, 664M Free Swap: 7808M Total, 4204K Used, 7804M Free
> 
>  PID USERNAME       THR PRI NICE   SIZE    RES STATE   C   TIME    WCPU COMMAND
>  997 asterisk        59  52    0   133M 61220K select  0 278:59   2.69% asterisk
> 16958 root             1  20    0 13308K  3448K CPU2    2   0:00   0.14% top
>  579 root             1  20    0 15252K  3116K select  1  35:01   0.07% ppp
>  933 root             1  20    0 10892K  1688K select  0   1:38   0.02% powerd
> 1038 root             1  20    0 11400K   764K nanslp  1   0:03   0.02% cron
>  930 root             1  20    0 18200K 18280K select  0   0:47   0.01% ntpd
> 1005 root             1  20    0 14772K  4516K bpf     3   0:13   0.00% arpwatch
>  834 root             1  20    0 11364K  1992K select  1   4:46   0.00% syslogd
>  847 bind             7  52    0 59528K 30600K sigwai  2   1:30   0.00% named
>  989 root             1  20    0 32264K  1716K nanslp  2   0:20   0.00% perl
>  863 daemon           1  20    0 11388K  1944K select  1   0:01   0.00% rpcbind
>  872 root             1  20    0 11096K  1840K autofs  2   0:01   0.00% automountd
>  975 root             1  20    0 14548K     0K nanslp  3   0:00   0.00% <smartd>
>  968 dhcpd            1  20    0 22972K  7648K select  0   0:00   0.00% dhcpd
>  878 root             1  20    0 10988K     0K kqread  1   0:00   0.00% <autounmountd>
> 13271 root             1  20    0 12104K  3128K wait    1   0:00   0.00% login
> 16955 root             1  26    0 13204K  4080K pause   3   0:00   0.00% csh
> 1034 root             1  20    0 18340K  3976K select  0   0:00   0.00% sshd
> 1084 root             1  52    0 10928K  1724K ttyin   2   0:00   0.00% getty

I'll  note that top was a -w that reports:

       -w     Display approximate swap usage for each process.

It can also sort the list by swap usage and
can show more processes (In case they are the
primary users of the sswap space.)

Something like:

top -CawSoswap

might show interesting information about what
is using swap space.



Going in another direction. . .

With only 1 GiByte of RAM and well over 7 GiByte of swap
(7808M), I wonder if your boot reports something like:

warning: total configured swap (??? pages) exceeds maximum recommended amount (??? pages).

If so, then quoting "man 8 loader" and its kern.maxswzone material,

                 Note that swap metadata can be fragmented, which means that
                 the system can run out of space before it reaches the
                 theoretical limit.  Therefore, care should be taken to not
                 configure more swap than approximately half of the
                 theoretical maximum.

is what that warning is about: Looking at the swapon_check_swzone code the
warning is reporting the "half" figure as "recommended", not reporting the
theoretical maximum. So, translating: "care should be taken to not
configure more swap than" the reported maximum recommended amount. (If I
understand correctly.) [These notes are from an older message for a
different context.]

I'll note that an RPI2 V1.1 and a RPI3, both with 1 GiByte of RAM,
get very different recommended figures (the text is copied from
an 2017-Dec-06 message that was probably for running what at the
time was a somwh,a old kernel, not a then-recent boot):

rpi2: . . . exceeds maximum recommended amount (411488 pages).
rpi3: . . . exceeds maximum recommended amount (925680 pages).

Pages are 4 KiBytes. Even the larger figure (RPI3) ends up
with only 925680*4KiBytes*(1MiByte/1024KiByte) == 3615.9375
MiByte recommended. In other words: far less than 7808M.

But your machine may well have a larger recommendation.


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
Received on Sat Mar 17 2018 - 15:51:45 UTC

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