Linux Format - UK (2020-03)

12 LXF260 March 2020 http://www.linuxformat.com

ANSWERS

faster. It is also worth bearing in mind that

if RAM does become short and the system

needs to swap out data, it will not

automatically swap it back in once RAM

becomes free. There is no point in the

system doing that until it is needed,

otherwise it would only have to swap

it out again the next time something

demanded more RAM.

4GB is not considered a lot of RAM

nowadays, especially when using a

heavyweight desktop like KDE. It is

certainly sufficient, but your system is

doing its best to make sure that as much

of that RAM as possible is available for use.

As long as your system is not frequently

moving data to and from swap, which will

really slow things down, your system is

working as it should. Use a memory

monitor, either one of the graphical ones

like KSysGuard or the terminal command

free -h to see what is going on.

I would be more worried if swap was not

being used, as it would mean that

unnecessary code was being allowed to

take up RAM instead of using the more

suitable resources available to it – swap is

there to be used.

Q

Early swap usage

I’m using Kubuntu 19.10 and

noticed that swap was used very early

after starting the desktop, even if there’s

still RAM available (4GB RAM, KDE

Plasma desktop). How can I troubleshoot

what’s causing this early use of swap?

isn’t swap supposed to be used only if

RAM is full? Can I do something about it?

Leon Butcher

A

This is not a problem to be solved, it

is the system working as it should.

Memory management in Linux is both

advanced and mature – years have gone

into optimising it. Data is moved from

memory to swap because it is unlikely to

be needed but has to remain available in

memory in some form. For example, code

used when starting up system services

may not need to be accessed once those

services are running, so it can be safely

paged to swap.

Linux will try to use all the memory

available to it. RAM not occupied with code

or data will be used for filesystem caching

to speed up disk usage. So swapping out

unneeded data can make your system

Got a burning question about open source or the kernel?

Whatever your level, email it to [email protected]

Q

No keyboard

I read the magazine and find it

really useful, although my computing

knowledge is limited. About 11 years back

I migrated to Linux. I’ve managed to deal

with all the hiccups except this one. My

wife was fed up with Windows problems

so I fitted a SSD and loaded Mint 17.3 on

her Toshiba Satellite L850D-12P laptop.

On boot up it doesn’t always find the

keyboard and touchpad. A forced power

off and reboot will fix it maybe the first

or second time. I’ve tried changing boot

from fast to normal as I guess it might be

something to do with timing, but no luck

with that.

Dave Fisher

A

The first thing to check is how your

keyboard and touchpad are

connected to the computer – meaning

what type of interface are they using

internally. You may be able to do this using

a program like lshw or lsusb. My suspicion

is that they use the USB bus internally. If

that is the case, go into your laptop’s

firmware configuration (what we used to

call the BIOS in simpler times) and look for

an option called USB Legacy or something

similar. Try toggling this setting, it affects

how USB keyboards and similar devices

are detected at early boot.

Does the keyboard work after you have

booted? You may need to alter your boot

options, in /etc/default/grub to make

Mint the default boot option – don’t forget

to run update-grub after changing any

Grub options. If it works, you may be able

to find an error message relating to it with:

$ sudo journalctl -b

in a terminal. The -b option tells it to show

entries since the last boot, which includes

the early messages from dmesg. This will

show what hardware detection is done by

the kernel. If you do find errors in here, try

pasting them into a search engine. If you

still have no keyboard after booting into

Linux, install openssh-server (if not already

installed) so you can SSH into the laptop

from your own computer, then you can

check the journal even without the use of a

physical keyboard.

While swap usage is usually low, more of it being used is not a bad thing. The only time it should affect

performance is when data is being frequently moved in and out of swap.

Answers

Neil

Bothwick

is debugging

your code as

we speak,

he’s inside

your home...

12 LXF260 March 2020 http://www.linuxformat.com

faster.It isalsoworthbearinginmindthat

if RAMdoesbecomeshortandthesystem

needstoswapoutdata,it willnot

automaticallyswapit backinonceRAM

becomesfree.Thereisnopointinthe

systemdoingthatuntilit isneeded,

otherwiseit wouldonlyhavetoswap

it outagainthenexttimesomething

demandedmoreRAM.

4GBisnotconsidereda lotofRAM

nowadays,especiallywhenusinga

heavyweightdesktoplikeKDE.It is

certainlysufficient,butyoursystemis

doingitsbesttomakesurethatasmuch

ofthatRAMaspossibleisavailableforuse.

Aslongasyoursystemisnotfrequently

movingdatatoandfromswap,whichwill

reallyslowthingsdown,yoursystemis

workingasit should.Usea memory

monitor,eitheroneofthegraphicalones

likeKSysGuardortheterminalcommand

free-htoseewhatisgoingon.

I wouldbemoreworriedif swapwasnot

beingused,asit wouldmeanthat

unnecessarycodewasbeingallowedto

takeupRAMinsteadofusingthemore

suitableresourcesavailabletoit – swapis

theretobeused.

Q

Earlyswapusage

I’musingKubuntu19.10and

noticedthatswapwasusedveryearly

afterstartingthedesktop,evenif there’s

stillRAMavailable(4GBRAM,KDE

Plasmadesktop).HowcanI troubleshoot

what’scausingthisearlyuseofswap?

isn’tswapsupposedtobeusedonlyif

RAMisfull?CanI dosomethingaboutit?

LeonButcher

A

This is not a problem to be solved, it

is the system working as it should.

Memory management in Linux is both

advanced and mature – years have gone

into optimising it. Data is moved from

memorytoswapbecauseit isunlikelyto

beneededbuthastoremainavailablein

memoryinsomeform.Forexample,code

usedwhenstartingupsystemservices

maynotneedtobeaccessedoncethose

servicesarerunning,soit canbesafely

pagedtoswap.

Linuxwilltrytouseallthememory

availabletoit.RAMnotoccupiedwithcode

ordatawillbeusedforfilesystemcaching

tospeedupdiskusage.Soswappingout

unneededdatacanmakeyoursystem

Gota burningquestionaboutopensourceorthekernel?

Whateveryourlevel,emailit [email protected]

Q

No keyboard

I read the magazine and find it

really useful, although my computing

knowledge is limited. About 11 years back

I migrated to Linux. I’ve managed to deal

with all the hiccups except this one. My

wife was fed up with Windows problems

so I fitted a SSD and loaded Mint 17.3 on

her Toshiba Satellite L850D-12P laptop.

On boot up it doesn’t always find the

keyboard and touchpad. A forced power

off and reboot will fix it maybe the first

or second time. I’ve tried changing boot

from fast to normal as I guess it might be

something to do with timing, but no luck

with that.

DaveFisher

A

The first thing to check is how your

keyboard and touchpad are

connected to the computer – meaning

what type of interface are they using

internally. You may be able to do this using

a program like lshw or lsusb. My suspicion

is that they use the USB bus internally. If

that is the case, go into your laptop’s

firmware configuration (what we used to

call the BIOS in simpler times) and look for

an option called USB Legacy or something

similar. Try toggling this setting, it affects

how USB keyboards and similar devices

are detected at early boot.

Does the keyboard work after you have

booted? You may need to alter your boot

options, in /etc/default/grub to make

Mint the default boot option – don’t forget

to run update-grub after changing any

Grub options. If it works, you may be able

to find an error message relating to it with:

$ sudo journalctl -b

in a terminal. The -b option tells it to show

entries since the last boot, which includes

the early messages from dmesg. This will

show what hardware detection is done by

the kernel. If you do find errors in here, try

pasting them into a search engine. If you

still have no keyboard after booting into

Linux, install openssh-server (if not already

installed) so you can SSH into the laptop

from your own computer, then you can

check the journal even without the use of a

physical keyboard.

While swap usage is usually low, more of it being used is not a bad thing. The only time it should affect

performance is when data is being frequently moved in and out of swap.

Answers

Neil

Bothwick

is debugging

your code as

we speak,

he’s inside

your home...