[fedora-arm] Re: Focusing on Zram
On 10/6/18 7:36 AM, Peter Robinson wrote:
On Fri, Oct 5, 2018 at 10:20 PM Robert Moskowitz
<rgm(a)htt-consult.com> wrote:
>
>
> On 10/5/18 2:54 PM, Peter Robinson wrote:
>
>>> One difference I note is F28 has a swap partition, F29 does not. Now
>>> during the initial stuff, no swap was used. Now I see 29KB of swap used
>>> with 86KB memory free.
>> So we use zram for swap in F-29, it preserves the mSD card due to
>> wear, and is much faster, this isn't the problem. Basically up to a
>> max of 50% of the RAM will be allocated to swap using lz4 compression
>> and we generally see a 4-5 times compression ratio.
> How can I 'see' my swap partition? Free shows a 487304B swap with none
> used. Yet.
>
> Nothing in fstab. Guess I better read up on zram.
It's created as part of the zram-swap service. The swapon (no options)
will show swap details, the zramctl cmd (no options) will show you
size, utiliation, compression ratios etc.
OK. I took a look at the output of these commands and how zram is
running as a service.
Pretty neat, overall.
Though I saw where that system start date may play a longterm problem:
cat /etc/zram.conf
# The factor is the percentage of total system RAM to allocate to the
ZRAM block device(s).
FACTOR=2
# cat /etc/systemd/system/swap.target.wants/zram-swap.service
[Unit]
Description=Enable compressed swap in memory using zram
DefaultDependencies=no
Before=swap.target
[Service]
Type=oneshot
RemainAfterExit=yes
TimeoutStartSec=30sec
ExecStart=/usr/sbin/zramstart
ExecStop=/usr/sbin/zramstop
[Install]
WantedBy=swap.target
# systemctl -l --no-pager status zram-swap
\u25cf zram-swap.service - Enable compressed swap in memory using zram
Loaded: loaded (/usr/lib/systemd/system/zram-swap.service; enabled;
vendor preset: disabled)
Active: active (exited) since Fri 2018-06-22 11:12:12 EDT; 3 months
16 days ago
Process: 437 ExecStart=/usr/sbin/zramstart (code=exited,
status=0/SUCCESS)
Main PID: 437 (code=exited, status=0/SUCCESS)
Jun 22 11:12:12 localhost zramstart[437]: Setting up swapspace version
1, size = 475.9 MiB (498999296 bytes)
Jun 22 11:12:12 localhost zramstart[437]: no label,
UUID=ba3bf62f-7bb0-4295-ad8c-2d26b000c3f8
Jun 22 11:12:12 localhost zramstart[437]: Activated ZRAM swap device of
499 MB
Jun 22 11:12:12 localhost systemd[1]: Started Enable compressed swap in
memory using zram.
Active for 3 months and 16 days? Hardly. :)
Perhaps for F30, you can grab the timestamp of the Chrony drift file for
the startup rather than whereever you get this Jun 22 date?
thanks for all the help!