Re: Δίνοντας options στην εντολή time
Nick Demou
ndemou at gmail.com
Sat May 31 19:46:37 EEST 2008
2008/5/30 George Notaras <gnot at g-loaded.eu>:
>[...]
> Σε γενικές γραμμές, υπάρχει κάποιος γρήγορος & εύκολος τρόπος να βρίσκει
> κανείς συγκεκριμένα στοιχεία για την κατανάλωση μνήμης από κάποιο process?
μέχρι πριν λίγες ημέρες όχι [1] αλλά τώρα ίσως να υπάρχει [2]
[1] http://lwn.net/Articles/230975/
Anybody who has tried to figure out why a Linux system is running
short of memory can attest that the memory usage information made
available by the kernel is, at best, difficult to use.
[2] http://kernelnewbies.org/LinuxChanges#head-0c37b7fd1de7e1eaef8f1783f4aedd969b76527c
Measuring how much memory processes are using is more difficult than
it looks, specially when processes are sharing the memory used [το
οποίο είναι πολύ συνηθισμένο σε desktop χρήση]. Features like
/proc/$PID/smaps (added in 2.6.14) help, but it has not been enough.
2.6.25 adds new statistics to make this task easier. A new
/proc/$PID/pagemaps file is added for each process. In this file the
kernel exports (in binary format) the physical page localization for
each page used by the process. Comparing this file with the files of
other processes allows to know what pages they are sharing. Another
file, /proc/kpagemaps, exposes another kind of statistics about the
pages of the system. The author of the patch, Matt Mackall, proposes
two new statistic metrics: "proportional set size" (PSS) - divide each
shared page by the number of processes sharing it; and "unique set
size" (USS) (counting of pages not shared). The first statistic, PSS,
has also been added to each file in /proc/$PID/smaps. In this HG
repository you can find some sample command line and graphic tools
that exploits all those statistics.
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