Memory Usage by KDE

[W. Wayne Liauh]

Thanks, now I begin to remember.  When KDE reports "used", it can mean 
that the memory either is being actively used or is being cached. 
 Typically I only have about 20 MB reported to be "un-used", I believe 
most of the "used" memory is being cached, otherwise I would have been 
paged to death.  As I didn't notice any system slow down, there is no 
paging to the swap partition at all.

On the other hand, when my "un-used" memory decreased to, say, 3 MB, it 
would stay at around that number, sometimes even increased, when I 
loaded another program, meaning that a good portionof the memory 
occupancy is only a leasehold, not a fee simple.  :-)

The Athlons seem to be doing a much better job in caching (remember the 
Athlons have three pipelines vis-a-vis only one for P3).  This may 
explain, though only partially, why the Athlons have a much better 
performance for some Linux graphic programs such as Corel Draw.

Thanks a lot for your answer.



Jeffrey Wong wrote:

>A couple of things to point out here.  Just because a memory check shows
>200M of memory being used, doesn't mean the memory is being used by any
>specific program (more on this later).  2nd, which column of the 'top'
>display are you using to get these stats?  The number in the size column
>is not exactly what you are looking for.  Long explanation on how how
>parts of the linux memory subsystem works follows.
>
>First a breakdown of the top display.  The size column lists the total
>amount of memory accessed by the a process.  This includes anything that
>may have been swapped to disk or taken from a shared memory structure or
>linked library.  The RSS column shows the size of all non swapped memory,
>but still includes the shared/linked lib memory.  The shared column list
>shared/liked lib memory used by the process.  So what is shared mem?  It's
>simply that, a segment of memory that is shared by several
>processes.  This shared memory will be counted several times if you just
>sum the numbers in the size column.  In some cases, shared memory can
>account for a large percentage of a process.  One example of this is when
>a process forks off instances of itself (like the kdeinit process).  Linux
>uses a copy on write fork which will initially have the new instances
>using 100% shared memory and as each child process goes on it's own way
>the percentage of shared memory generally decreases.  
>In addition, the top 'share' column also includes linked libraries.  If
>several programs link to the same library call, the the amount of mem used
>by that library routine will be counted in each processes 'share' entry,
>even though the actual lib routine is only in memory once.  This is one of
>the reasons why the shared number in the mem line across the top of the
>display never matches what is in the 'share' column, the top number
>doesn't include linked lib's, while the 'share' column does.
>
>Unfortunately, even though top is not a good tool for this, I don't really
>know of anything better :(
>
>Next, the amount of memory reported as used is not the amount of memory
>used by what people generally refer to as used memory (did that sentence
>make any sense at all?  Go away, I'm tired).  The general linux attitude
>toward memory uses is, if it's there and not being used, it's a wasted
>resource.  Generally speaking, on any linux system that's been used for a
>while there will less than maybe 10% of memory that's unused, even if at
>the time there are no real programs running (by this i mean only the core
>system processes are running).  Basically, if linux finds a significant
>amount of memory going unused, it'll grab it and use it for file caching
>and I/O buffering.  This memory will be freed for use by other processes
>whenever needed.  Thus the amount of available memory is the amount top
>lists as free + the amount top lists as buffer + the amount used by file
>caching (which top doesn't report at all).  The better way to figure the
>amount of mem available is to use 'free'. free gives the same numbers for
>free mem and buffer mem, but it also gives the amount of mem used for file
>caching.  
>
>I'm tired of writing about a boring memory management stuff.  I hated it
>in school, I hated it when I had to do memory monitoring stuff, and I hate
>it now.
>
>Jeff
>
>
>On Wed, 15 Aug 2001, W. Wayne Liauh wrote:
>
>>X takes 60.8 M, and there are 7 "kdeinit" processes, each taking about 5 ~ 8 
>>M, 2 "kdm" proocesses 14M altogether, "knotify" 8.5M, ksmserver 5.3M, and 
>>"xfs" 7.5M.  These are the major memory users.
>>
>>On Wednesday 15 August 2001 12:43 pm, you wrote:
>>
>>>Can you run "top" and see which process(es) is using that amount of memory?
>>>
>>>----- Original Message -----
>>>From: "W. Wayne Liauh" <LiauhW001 at Hawaii.rr.com>
>>>To: "Linux & Unix Advocates & Users" <luau at list.luau.hi.net>
>>>Sent: Wednesday, August 15, 2001 11:05 AM
>>>Subject: [luau] Memory Usage by KDE
>>>
>>>>As I mentioned in a previous thread, without running any program, KDE
>>>>takes up about 210 MB RAM.  If I turned the anti-aliasing fonts on, the
>>>>memory usage elevated to 230 MB.
>>>>
>>>>With GNOME, the memory usage was about 67MB.
>>>>
>>>>Did I do anything wrong?  Thanks.
>>>>
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>
>
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