Hacking Ubuntu to Improve Performance

[newbie2]

This feature includes various hacks to boost Ubuntu's performance, such as viewing running processes, identifying resources, finding process startups, tuning kernel parameters, and speeding up boot time. This is a complete chapter in the ExtremeTech book "Hacking Ubuntu: Serious Hacks Mods And Cusomtizations."
http://www.extremetech.com/article2/0,1697,2114115,00.asp
:cool:

[DC@DR]

Wow, such a valuable link, thanks for sharing it :-)

[kostkon]

Cool, thanks!!

[jamesrl]

Be sure to read the comments section, as there is some questionable advice in the article. Particularly the comment that Ubuntu can only use 1 Gb of physical memory; my laptop has 2 Gb of memory, and Ubuntu Edgy/Feisty has always been using all of it (I didn't have 2 Gb with Breezy/Dapper) according to system monitors (e.g. "free", or "cat /proc/meminfo").

Checking my current memory usage (running with kubuntu feisty a few web browsers open (both with konqueror, firefox), kontact (kmail, akregator, kalendar, kgpg), konsole, a few system monitors (superkaramba), some music (amarok), beryl for desktop effects, and many daemons running in the background (sshd, php, apache, etc), I see:


jamesrl@redsox2007:~$ free -m
total used free shared buffers cached
Mem: 2018 1703 315 0 230 754
-/+ buffers/cache: 718 1299
Swap: 2047 0 2047

and then turning on windows XP in a virtual machine (Virtual Box) that allocates 512 Mb to it to boost up my memory usage, I get



jamesrl@redsox2007:~$ free -m
total used free shared buffers cached
Mem: 2018 1965 53 0 30 629
-/+ buffers/cache: 1305 712
Swap: 2047 0 2047

This seems like its properly using all of my 2Gb of memory, even properly utilizing unused memory as "cache" (754 Mb in normal operation when plenty of free memory) and then shrinking that cache when more memory is being used (it moved down to 629 Mb of memory when it ran out of free memory).

I usually have an applet in the monitoring cpu/mem/swap usage, and have never noticed swap being used at all (except for hibernation; and maybe once using like 2 Mb out 2 Gb).

When someone from the ubuntu team challenged him on this in the comments, he tried defending it with some article (http://kerneltrap.org/node/2450) from February 2004, saying that the 2.6 kernel (2.6.3 or so in 2/2004), can't handle more than 1 Gb of physical memory. [I'm not an expert on memory usage; the article could possibly be technically true still, e.g. maybe the kernel can only access 1 Gb and other programs can access more than that; or its due to the difference between high and low memory or something.]

But i am trying to say ubuntu clearly can properly utilize systems with at least 2 Gb of memory (at least in 2007; right now im running feisty's 2.6.20-15).

[jamesrl]

Also don't trust the part about how cron is wasted; by default lots of things are installed in cron. For example, just look in:


/etc/cron.daily/
/etc/cron.weekly/
/etc/cron.monthly/
In cron.daily I find scripts that update the locate database, the apt package descriptions, updates the man database, rotates the logs, among other things. [This way i don't have to wait forever to search for a file with locate, or run sudo updatedb, every day myself.]

In cron.weekly / cron.monthly
there's things like popularity-contest and stuff with logs that should be done occasionally but not necessarily every day.