79 lines
2.9 KiB
Plaintext
79 lines
2.9 KiB
Plaintext
getrusage
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For a detailed description about the values returned by
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getrusage() please consult your usual C programming
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documentation about getrusage() and also the header file
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sys/resource.h. The $ru_who argument is either
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RUSAGE_SELF (the current process) or RUSAGE_CHILDREN (all
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the child processes of the current process). On some
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(very few) systems (those supporting both getrusage() and
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the POSIX threads) there is also RUSAGE_THREAD. The
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BSD::Resource supports the _THREAD flag if it is present
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but understands nothing about the POSIX threads
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themselves.
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Note 1: officially HP-UX 9 does not support getrusage() at
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all but for the time being, it does seem to.
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Note 2: Solaris claims in sys/rusage.h that the ixrss and
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the isrss fields are always zero.
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getrlimit
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Processes have soft and hard resource limits. At soft
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limit they receive a signal (XCPU or XFSZ, normally) they
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can trap and handle and at hard limit they will be
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ruthlessly killed by the KILL signal. The $resource
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argument can be one of
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RLIMIT_CPU RLIMIT_FSIZE
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RLIMIT_DATA RLIMIT_STACK RLIMIT_CORE RLIMIT_RSS
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RLIMIT_NOFILE RLIMIT_OPEN_MAX
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RLIMIT_AS RLIMIT_VMEM
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The last two pairs (NO_FILE, OPEN_MAX) and (AS, VMEM) mean
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the same, the former being the BSD names and the latter
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SVR4 names. Two meta-resource-symbols might exist
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RLIM_NLIMITS
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RLIM_INFINITY
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NLIMITS being the number of possible (but not necessarily
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fully supported) resource limits, INFINITY being useful in
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setrlimit().
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NOTE: the level of 'support' for a resource varies. Not
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all the systems
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a) even recognise all those limits
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b) really track the consumption of a resource
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c) care (send those signals) if a resource limit get exceeded
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Again, please consult your usual C programming
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documentation.
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One notable exception: officially HP-UX 9 does not support
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getrlimit() at all but for the time being, it does seem
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to.
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getpriority
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The priorities returned by getpriority() are
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[PRIO_MIN,PRIO_MAX]. The $which argument can be any of
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PRIO_PROCESS (a process) PRIO_USER (a user), or PRIO_PGRP
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(a process group). The $pr_who argument tells which
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process/user/process group, 0 signifying the current one.
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setrlimit
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A normal user process can only lower its resource limits.
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Soft or hard limit RLIM_INFINITY means as much as
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possible, the real limits are normally buried inside the
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kernel.
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setpriority
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The priorities handled by setpriority() are
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[PRIO_MIN,PRIO_MAX]. A normal user process can only lower
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its priority (make it more positive).
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