why is firefox such a CPU hog?

[Lieven Van Acker]

Hey, 

I even went some step further in the LocalApps setup: I'm currently running LTSP (karmic), with virtualbox (yes!) as localapp. Storage (the virtual disk-image) is on a the ltsp-server, and exported via ATA-over-ethernet to the client network. I'm running Windows perfectly virtualised on these dual core low power ATOM based thin clients... 

.... 

If anyone is interested, I put down some words about this on a wiki 

Regards, 

Lieven 

----- Oorspronkelijk bericht ----- 
Van: "David Groos" <djgroos at gmail.com> 
Aan: edubuntu-users at lists.ubuntu.com 
Verzonden: Maandag 16 november 2009 22:25:05 GMT +01:00 Amsterdam / Berlijn / Bern / Rome / Stockholm / Wenen 
Onderwerp: Re: why is firefox such a CPU hog? 

I'd like to tell you about my felicity with localapps. Last spring when I finally got LTSP running and throughout the spring firefox did most of what I asked it to do... except it couldn't do flash video and even java applets like the ones at this famous site were very pokey. But that was pretty much OK. But, what brought my curriculum to it's knees was not being able to run CmapTools, a java based application. The server would bog down with just 1 or at max 2 computers running CmapTools. 

The development of localapps has saved the day for my class/curriculum. Firefox and CmapTools work quite well as localapps using PIII and PIV computers with no more than 512 MB RAM. I can't say enough good stuff about what they let me do. Localapps IS the reason I upgraded to Jaunty. 

I'll too help you make the move to Jaunty--I can't say number of hours on a thing like this (alas, one never knows), but it is worth it if you need cpu hogs as tools for your students. If I can help let me know as well! 

Good Luck 
David 


On Mon, Nov 16, 2009 at 2:10 PM, Scott Balneaves < sbalneav at legalaid.mb.ca > wrote: 



On Mon, Nov 16, 2009 at 11:08:37AM -0800, john wrote: 
> Hi Asmo, 
> 
> On Mon, Nov 16, 2009 at 10:36 AM, < asmo.koskinen at arkki.info > wrote: 
> 
> > Do you know what they are doing/what kind of web pages they are surfing - 
> > flash, java, lots of pictures, some kind of embedded movies or embedded 
> > audio players, lots of popup windows and so on - FF has n+1 plugins - bad, 
> > bad dog. But maybe FF is not so bad, but bad design for web pages can do 
> > that. 
> 
> They are probably surfing all of the above, since that is the nature 
> of the web these days. I think If 
> LTSP is going to be viable 

Right, because we're only celebrating our 10th anniversary. It's not like 
we're viable or anything :) 


> it has to be able to work at least as well 
> as other computers that kids use 
> e.g. 4 year old stand alone workstations, 2Ghz, running WinXP with 512 
> mb ram. 

Well, it certainly does. I run about 40 people off one server. Trick is, I 
don't load flash. Now, I'm at a business, and can control this. Flash is a 
"poorly" behaved application: it essentially assumes you're one person running 
on 1 machine. So if you have 30 kids trying to watch flash movies, yeah, you 
either need a machine with 30x the power of your 2 ghz machine, or you need to 
spread the load around. 

Which is why we developed localapps. Offload the firefox on the thin client. 


> If LTSP/Ubuntu can't manage that the students and teachers 
> don't tend 
> to be sympathetic. We are using google apps a lot these days, and it 
> would be a bad thing for the future of LTSP at our district if we 
> figured out that LTSP wasn't up to Web 2.0 or what have you. 

LTSP is NOT a panacea. A thin client will never, EVER be 100% of the 
experience of a full workstation. We've done lots of things to make LTSP as 
"like" a full workstation as we can, with things like Localapps, that allows 
you to offload some of the work on the thin client itself. There's also 
Stephane's ltsp-cluster work which can also address this problem. 

However, the reality is, if you've got 30 kids each consuming 2ghz of 
processing power playing with flash stuff, then you're either going to need the 
equivalent of a 60ghz processor, or enough processors (say, 5 3ghz intel 
quadcores) to come up to the same processing power. 

Or, help out projects like Gnash which do the same thing for MUCH less cpu. By 
way of a "single case" instance, here's a line out of top, with me viewing a 
youtube video using the adobe flash player: 

2049 sbalneav 20 0 495m 120m 35m S 38 6.0 4:09.80 firefox 

The "38" column's important. That's 38% cpu usage. This is on a dual-core 
3.0ghz workstation with 2 gigs of ram. A not inconsiderable box. 38%, over a 
1/3 busy. So, if I hosted 2 other terminals, and THEY were watching youtube, 
I'd be at 100% util. 

Now, Here's me watching the same video, using Totem as my movie viewer: 

4208 sbalneav 20 0 201m 43m 20m S 6 2.2 0:02.41 totem 

6 percent. So, if I had 15 other terminals hanging off my box, watching 
youtube videos, I'd be at 100% 

3. Versus 16. 

The problem here isn't LTSP. LTSP can't "manufacture" cpu cycles out of thin 
air. If a badly behaved application uses up all your cpu cycles, there's 
nothing LTSP can do about that: it's just a way of running remote X. 


> Thanks, I am defiantly looking around for Firefox optimization tricks, 
> although this link is about memory issues and my problem seems to be 
> CPU usage on the server. Running top on the thin clients shows me that 
> I have ram to spare. 

Then LocalApps may be your answer. 


> As I said, my question is partly a philiopical rumination e.g I am 
> really wondering why Linux/LTSP can be brought to it's knees by a 
> single user running a web-browser. 

Because LTSP hasn't been brought to it's knees. The SERVER has been brought to 
it's knees by flash. 

It's just that, WITHOUT ltsp, you never SEE the box being brought to it's knees 
because, well, while you're watching the video, you're not doing anything else. 

Scott 

-- 
Scott L. Balneaves | The closest you will ever come in this life to an 
Systems Department | orderly universe is a good library. 
Legal Aid Manitoba | -- Ashleigh Brilliant 




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