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Re: [LUG] X eating 300Mb (and other memory problems)

 

Simon Williams wrote:
> I'm a little confused about the memory usage on my laptop (or maybe I 
> just can't add). Here are the first few lines from top, sorted by memory 
> usage:
> 
> Mem:    511616k total,   379724k used,   131892k free,    12284k buffers
> Swap:  1036152k total,     1244k used,  1034908k free,   233320k cached
> 
>    PID USER      NI S  VIRT  RES SWAP %CPU %MEM    TIME+  COMMAND
> 29070 simon      0 S  154m  52m 101m  0.0 10.4   0:28.43 firefox-bin
> 29110 simon      0 S  151m  47m 104m  0.0  9.4   0:12.80 thunderbird-bin
> 28735 root       0 R  313m  17m 295m  0.5  3.6   0:14.46 X

...

> Just to clarify: VIRT = RES + SWAP, right?

Sort of, but perhaps not quite the way you think.

> Now, the last time I checked, 154 + 151 + 313 = 618, which is a lot than 
> the 380 shown in the summary, and that's just taking the first 3 lines, 
> never mind the countless other processes using up to 35Mb each.
> Can anyone explain how 600Mb-1Gb of processes fit into 380Mb of RAM?

You probably have to make allowances for the fact that shared libraries
are part of each process's virtual address space, but should only have
one physical image in core.  AFAIR program text (ie code) can also get
paged out by being thrown away, since it's always possible to retrieve
it again later from disk.  I'm not sure if that still happens though.

> I know firefox and thunderbird are memory hogs- they eat 150Mb on every 
> system I use them on, but X usually takes 50Mb at most- not the 300 odd 
> I get on this system. I tried logging out and restarting X, but even 
> with no-one logged in it shows as 260Mb or more.

X does seem a bit extreme.  On my Fedora 7 box, running an 8x2 virtual
desktop at 1680x1050 it's still only using ~175MB.  ISTR that earlier
releases were more memory-hungry though.  (OTOH, thunderbird has a
resident set size of half a gigabyte at the moment :(

James

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