This link has been bookmarked by 122 people . It was first bookmarked on 02 Mar 2006, by Mike.
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VSZ RS
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What it is really doing is showing how much real memory each process would take up if it were the only process running
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they simply report how much memory a process uses, regardless of whether that memory is shared with other processes as well.
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One important thing to note about the output is that each shared library is listed twice; once for its code segment and once for its data segment
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If you run KDE for your desktop, but mostly use Gnome applications, then you are paying a large price for a lot of redundant (but different) shared libraries
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Shared libraries only share backing store if the code can be run without modification - i.e., it was compiled as position-independent code
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wo of the possible outputs are VSZ and RSS, which stand for "virtual set size" and "resident set size", which are commonly used by geeks around the world to see how much memory processes are taking up.
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Orsa MundiThis entry is for those people who have ever wondered, "Why the hell is a simple KDE text editor taking up 25 megabytes of memory?" Many people are led to believe that many Linux applications, especially KDE or Gnome programs, are "bloated" based solely upon what tools like ps report. While this may or may not be true, depending on the program, it is not generally true -- many programs are much more memory efficient than they seem.
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20 Sep 10
Vitaly UnknownEnough talk; let's see what the situation is with that "huge" KEdit process. To see what KEdit's memory looks like, we'll use the pmap program (with the -d flag):
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Koteo Oteoat the bottom of the output. This is what can be considered the incremental cost of th
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Alvaro Chandiaapproach; neither number is an accurate picture of what the memory cost of running KEdit is.
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VSZ and RSS, which stand for "virtual set size" and "resident set size"
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either number is an accurate picture of what the memory cost
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Due to this sharing, Linux is able to use a great trick: it will load a single copy of the shared libraries into memory and use that one copy for every program that references it.
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"writeable/private" total,
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e cost to run this instance
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What it is really doing is showing how much real memory each process would take up if it were the only process running.
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Linux is able to use a great trick: it will load a single copy of the shared libraries into memory and use that one copy for every program that references it.
For better or worse, many tools don't care very much about this very common trick; they simply report how much memory a process uses, regardless of whether that memory is shared with other processes as well. -
we'll use the pmap program (with the -d flag):
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especially true when you deal with programs that create a lot of identical children processes, like Apache. ps might report that each Apache process uses 10 megabytes of memory, when the reality might be that the marginal cost of each Apache process is 1 megabyte of memory
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A well-behaved app can still end up eating many, many MB of memory that it isn't actually using.
For example, say the app need to make a number of large allocations for some temporary working space for some operation. It also needs to allocate some book keeping information (undo history, for example) and other bits of info to store/utilize the computed data.
When allocations are made, the heap grows. However, the heap can only shrink by truncation. This is, the program can only release memory back to the OS by shrinking the heap, not by cutting it into pieces. So if the app makes many allocations, and frees only some (or even most) of them, its heap may end up looking like:
X: free memory
U: used memory
UUUXXXXXXXXXXXXU
That's four pages of used memory and 12 pages of unused memory that can't be freed. -
If you run KDE for your desktop, but mostly use Gnome applications, then you are paying a large price for a lot of redundant (but different) shared libraries. By sticking to just KDE or just Gnome apps as much as possible, you reduce your overall memory usage due to the reduced marginal memory cost of running new KDE or Gnome applications, which allows Linux to use more memory for other interesting things (like the file cache, which speeds up file accesses immensely).
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jimohalloranExcellent blog post describing why the memory usage numbers reported by common system utilities such as ps and top are somewhat misleading.
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viniciusjlThis entry is for those people who have ever wondered, "Why the hell is a simple KDE text editor taking up 25 megabytes of memory?" Many people are led to believe that many Linux applications, especially KDE or Gnome programs, are "bloated" based solely u
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10 Feb 06
jason mMaybe this is a valid answer to Gentoo dimwits that like *box window managers because they have nice ps output.
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Page Comments
Enough talk; let's see what the situation is with that "huge" KEdit process. To see what KEdit's memory looks like, we'll use the pmap program (with the -d flag):
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