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#1 2012-01-24 12:35:11

masteryod
Member
Registered: 2010-05-19
Posts: 433

i686 vs amd64 [memory consumption]

Hi, I was running 64bit version of Arch from the beginning and never had problems with it but couple days ago I installed i686 on a USB hard drive and I was surprised about it's memory footprint it was significantly smaller than on 64bit version (not near ~20% percent as many thinks). Today I've run some test on virtualbox and this are the results:

right: up-to-date Arch i686
        idle: ~150MB
        firefox: ~270MB
        single user mode: 15MB
        startx: 36MB

left:   up-to-date Arch x86_64   
        idle: ~235MB (56.67% more)
        firefox: ~430MB (59.26% more)
        single user mode: 35MB (133% more)
        startx: 67MB (86.11% more)


(both fairly similar configs, firefox has equal loaded pages)

http://image.bayimg.com/eamejaadc.jpg
http://image.bayimg.com/eamelaadc.jpg

Is it normal?

Last edited by masteryod (2012-01-24 12:35:43)

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#2 2012-01-24 13:23:08

Army
Member
Registered: 2007-12-07
Posts: 1,784

Re: i686 vs amd64 [memory consumption]

Yes this is normal. There's informations about this all over the web, just use a search engine.

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#3 2012-01-24 13:42:55

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,492

Re: i686 vs amd64 [memory consumption]

In the past i measured it to be about 25% larger, not THAT larger.
After that i switched back to 32bit pae kernel with some packages recompiled with optimized cflags.

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#4 2012-01-24 13:52:33

Gusar
Member
Registered: 2009-08-25
Posts: 3,466

Re: i686 vs amd64 [memory consumption]

Army wrote:

Yes this is normal. There's informations about this all over the web, just use a search engine.

I think what masteryod is getting at is the extent of the increase in ram usage. Common wisdom is a 25-30% increase, but what masteryod (hmm, was that meant to be masteryoda smile) is seeing is significantly higher than that.

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#5 2012-01-24 14:32:07

masteryod
Member
Registered: 2010-05-19
Posts: 433

Re: i686 vs amd64 [memory consumption]

Gusar wrote:

I think what masteryod is getting at is the extent of the increase in ram usage. Common wisdom is a 25-30% increase, but what masteryod (hmm, was that meant to be masteryoda smile) is seeing is significantly higher than that.

Exactly my point, I knew that x86_64 is more memory hungry but I didn't expect such a big difference

PS no it's supposed to be "masteryod" I just needed some login and everything else was already used wink

Last edited by masteryod (2012-01-24 14:32:36)

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#6 2012-01-24 14:46:16

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,492

Re: i686 vs amd64 [memory consumption]

d'you tried to echoing 3 to /proc/sys/vm/drop_caches before the measurement?

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#7 2012-01-24 15:17:07

masteryod
Member
Registered: 2010-05-19
Posts: 433

Re: i686 vs amd64 [memory consumption]

Unfortunately I did not but I'm interested only in ram usage without caches (drop_caches doesn't affect this one if I understand correctly) and both machines were just after cold boot (virtualbox proved observations of real systems)

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#8 2012-01-24 15:21:11

kokoko3k
Member
Registered: 2008-11-14
Posts: 1,492

Re: i686 vs amd64 [memory consumption]

Echoing 3 will clear all of the caches (including slab, which isn't normally taken into account by ram measurement tools).
So it is a try i would do before wondering why the difference is so big.

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#9 2012-01-25 10:30:40

masteryod
Member
Registered: 2010-05-19
Posts: 433

Re: i686 vs amd64 [memory consumption]

ok, new results with "echo 3 > /proc/sys/vm/drop_caches" before every measurement:

idle:         ~134 vs ~214  (59.7% more)
firefox:      ~240 vs ~340  (41.67% more)
single user:   ~14 vs  ~30  (114.3% more)
startx:        ~37 vs  ~60  (62.16% more)

I don't know if it's because of virtualbox but after a while X consumes 60MB (even 130MB) on x86_64 and only 16-23MB on i686

We could use some poll and see how it hits other users

PS hmm is it possible that 32libs are responsible for that? my x86_64 setup has multilib enabled (maybe I'll setup "clean" 64bit system and see)

Last edited by masteryod (2012-01-25 10:57:50)

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#10 2012-01-25 12:22:23

.:B:.
Forum Fellow
Registered: 2006-11-26
Posts: 5,819

Re: i686 vs amd64 [memory consumption]

If they are loaded yes, but e.g. Firefox is 64 bit on Arch, so...

I noticed myself x86_64 uses quite some RAM on Arch.


Got Leenucks? :: Arch: Power in simplicity :: Get Counted! Registered Linux User #392717 :: Blog thingy

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#11 2012-01-26 10:23:01

masteryod
Member
Registered: 2010-05-19
Posts: 433

Re: i686 vs amd64 [memory consumption]

Just found this: https://bbs.archlinux.org/viewtopic.php?id=107473

so I suppose these differences are "normal", but I'm still amazed, I really didn't expect so much difference

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