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  #1  
Old 7th August 2008, 04:43 AM
tjsullivan1 Offline
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Inefficient Use of System resources

I recently installed Fedora 9 on my Macbook with two gigs of RAM. Since this is a dual boot system, I am able to compare the two operating systems side by side (i.e. F9 and Mac OS X 10.5). I have no problem with configuration issues or anything of that sort, but I found it disturbing that fedora uses 800 megs of ram with just gnome and firefox, whereas Leopard uses only 500 m for the same tasks (different desktop managers of course, but just the X windows and firefox).

Is this a sign that I have configured fedora incorrectly, or does fedora really use this much RAM?
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  #2  
Old 7th August 2008, 04:56 AM
Hlingler Offline
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I think that if you search the forums, you will find that similar questions have been asked before.

The general response seems to be along the lines of: yes, Linux is like that with RAM - that's what it's (RAM) is there for - to be used. I'm no expert, but I've read suggestions that it is actually more efficient to keep stuff in RAM, rather than swap it out or dump it. If it's really needed for something else, it'll be swapped out. That makes sense to me.

Or, was there some other use that you had planned for that RAM?

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V
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  #3  
Old 7th August 2008, 05:02 AM
tjsullivan1 Offline
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Well, I guess I was just shocked by it using 800 meg for such simple tasks. I have only previously used Linux for my servers (I've been running Ubuntu for a little over two years on them), and they have always seemed to be more efficient with system resources. I was surprised when I discovered that it was using so much ram (to compare, one of my older servers running Ubuntu 8.04 server edition - no gdm - uses only 100 megs of ram).

I don't currently have any other uses for the ram (I still have 1.2 gig free), I just wanted to make sure that I hadn't made an error in my install. Thanks!
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  #4  
Old 7th August 2008, 05:11 AM
Hlingler Offline
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Well, I suppose it is a valid concern, and a legitimate question if you're not used to seeing that much RAM in use. But:
> GNOME in F9 and FireFox are both (ahem) notorious resource hogs. I can't verify GNOME because I don't have it on my F9 install, but FireFox for sure, especially if you haven't yet updated to FF3.*+.
> Also depends on how much you have going on: how many tabs open, windows open, etc.
> Check background services/daemons that may be silently eating resources: http://www.mjmwired.net/resources/mjm-services-f9.html

V
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  #5  
Old 7th August 2008, 05:14 AM
bingoUV Offline
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How did you figure out the RAM usage? Depending on this, the 800 may include/exclude the cache/buffers. Post the output of
Code:
cat /proc/meminfo
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  #6  
Old 7th August 2008, 05:24 AM
marko Offline
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The thing to remember is if you run long enough after the last boot, Linux will buffer and cache almost any amount of RAM. It doesn't matter because if the kernel is asked to load a process it will first try the free window, then if it needs more it will release some of the oldest cached memory. Only if it completely runs low on buffered and cached RAM will it have to resort to swap. It's when you have to go to swap that you need to worry, the "free" command will show you the used RAM and then the used RAM - (Buffered + Cache) == the RAM you're actually using for apps. This is my "free" result on a development machine with 8GB of RAM:
Quote:
$> free
total used free shared buffers cached
Mem: 8199076 1897868 6301208 0 128656 828572
-/+ buffers/cache: 940640 7258436
Swap: 8193140 0 8193140

$>uptime
00:25:24 up 1 day, 3:25, 2 users, load average: 0.05, 0.21, 0.18

So after 27 hours since the last boot, it's used 1897868 KB but 128656+828572 is buffered and cached so the real App usage is 940640 KB and I really have 7258436 KB still available in the RAM if I needed it.
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  #7  
Old 7th August 2008, 05:39 AM
lazlow Offline
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Another thing to look out for is that Fedora is notorious for starting a ton of services that most people do not need. I can usually shut off about 1/3 of the services that are started by a default install of Fedora. Most other distros do not start these services by default.
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  #8  
Old 7th August 2008, 06:00 AM
w5set Offline
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And quite frankly caching "stuff" in ram saves a bit of time..usage of lots of ram (apparent usage) doesn't really take much away from the cpu...all that memory still has to be refreshed if it's empty or used, cached or trashed.
Swapping into/out of disk takes much more.
And modern refresh cycle times are just shy of totally marvelous compared to even stuff from just a few years ago now.
But non-the-less...most of Linux is tweakable...so make the cache(s) size smaller or totally just dump programs after you are done, if it's really admirable for memory to set unused. (uncached)
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