/proc/sys/vm/compact_memory doesn't exist in Ubuntu 20.04, delete ref…

[tjcw]

…erence to it.

Why I did it

Builld was failing for PLATFORM=vs on a Ubuntu 20.04 system

How I did it

Edited scripts/build_kvm_image.sh to knock out line which was referring to /proc/sys/vm/compact_memory

How to verify it

Eyeball the affected script

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012
• 202106

Description for the changelog

A picture of a cute animal (not mandatory but encouraged)

[lguohan]

not sure if this is true.

root@ubuntu:/home/ubuntu# uname -a
Linux ubuntu 5.4.0-1045-raspi #49-Ubuntu SMP PREEMPT Wed Sep 29 17:49:16 UTC 2021 aarch64 aarch64 aarch64 GNU/Linux
root@ubuntu:/home/ubuntu# cat /etc/os-release 
NAME="Ubuntu"
VERSION="20.04.1 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.1 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
root@ubuntu:/home/ubuntu# ls -l /proc/sys/vm/compact_memory 
--w------- 1 root root 0 Oct 27 19:56 /proc/sys/vm/compact_memory

[lguohan]

what kernel are you using? i suggest to check if the file exists or not, if not then we can skip.

[tjcw]

I have

openstack@tjcw-sonic-build:~$ uname -a
Linux tjcw-sonic-build 5.4.0-1047-kvm #49-Ubuntu SMP Mon Sep 20 21:27:33 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
openstack@tjcw-sonic-build:~$ ls -l /proc/sys/vm/compact_memory
ls: cannot access '/proc/sys/vm/compact_memory': No such file or directory
openstack@tjcw-sonic-build:~$ cat /etc/os-release
NAME="Ubuntu"
VERSION="20.04.3 LTS (Focal Fossa)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu 20.04.3 LTS"
VERSION_ID="20.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=focal
UBUNTU_CODENAME=focal
openstack@tjcw-sonic-build:~$

I'm using the kvm kernel, i.e. the one designed for running in a VM, becuase I'm running my builds in the IBM cloud. Maybe the kvm kernel accounts for the difference.

Probably best to check for the existence of the file and only write it if it's there.

[saiarcot895]

@tjcw on your system, what's the output of grep CONFIG_COMPACTION /boot/config-$(uname -r)? I'm guessing that it will say something like # CONFIG_COMPACTION is not set, or CONFIG_COMPACTION=n.

That kernel config controls whether or not /proc/sys/vm/compact_memory is available. Because of this, I agree that this should be changed to check if the file is there, and, if so, write to that file.

[tjcw]

openstack@tjcw-sonic-build:~$ grep CONFIG_COMPACTION /boot/config-$(uname -r)
# CONFIG_COMPACTION is not set
openstack@tjcw-sonic-build:~$ 

[saiarcot895]

That confirms it. The kernel that you're running has that config disabled, so /proc/sys/vm/compact_memory doesn't exist.

[tjcw]

Closing to revise to check for file being writeable