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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-05-24 04:52:22 +0000 |
commit | 3d08cd331c1adcf0d917392f7e527b3f00511748 (patch) | |
tree | 312f0d1e1632f48862f044b8bb87e602dcffb5f9 /man2/getitimer.2 | |
parent | Adding debian version 6.7-2. (diff) | |
download | manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.tar.xz manpages-3d08cd331c1adcf0d917392f7e527b3f00511748.zip |
Merging upstream version 6.8.
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'man2/getitimer.2')
-rw-r--r-- | man2/getitimer.2 | 278 |
1 files changed, 0 insertions, 278 deletions
diff --git a/man2/getitimer.2 b/man2/getitimer.2 deleted file mode 100644 index 6674117..0000000 --- a/man2/getitimer.2 +++ /dev/null @@ -1,278 +0,0 @@ -.\" Copyright 7/93 by Darren Senn <sinster@scintilla.santa-clara.ca.us> -.\" and Copyright (C) 2016, Michael Kerrisk <mtk.manpages@gmail.com> -.\" Based on a similar page Copyright 1992 by Rick Faith -.\" -.\" %%%LICENSE_START(FREELY_REDISTRIBUTABLE) -.\" May be freely distributed and modified -.\" %%%LICENSE_END -.\" -.\" Modified Tue Oct 22 00:22:35 EDT 1996 by Eric S. Raymond <esr@thyrsus.com> -.\" 2005-04-06 mtk, Matthias Lang <matthias@corelatus.se> -.\" Noted MAX_SEC_IN_JIFFIES ceiling -.\" -.TH getitimer 2 2023-10-31 "Linux man-pages 6.7" -.SH NAME -getitimer, setitimer \- get or set value of an interval timer -.SH LIBRARY -Standard C library -.RI ( libc ", " \-lc ) -.SH SYNOPSIS -.nf -.B #include <sys/time.h> -.P -.BI "int getitimer(int " which ", struct itimerval *" curr_value ); -.BI "int setitimer(int " which ", const struct itimerval *restrict " new_value , -.BI " struct itimerval *_Nullable restrict " old_value ); -.fi -.SH DESCRIPTION -These system calls provide access to interval timers, that is, -timers that initially expire at some point in the future, -and (optionally) at regular intervals after that. -When a timer expires, a signal is generated for the calling process, -and the timer is reset to the specified interval -(if the interval is nonzero). -.P -Three types of timers\[em]specified via the -.I which -argument\[em]are provided, -each of which counts against a different clock and -generates a different signal on timer expiration: -.TP -.B ITIMER_REAL -This timer counts down in real (i.e., wall clock) time. -At each expiration, a -.B SIGALRM -signal is generated. -.TP -.B ITIMER_VIRTUAL -This timer counts down against the user-mode CPU time consumed by the process. -(The measurement includes CPU time consumed by all threads in the process.) -At each expiration, a -.B SIGVTALRM -signal is generated. -.TP -.B ITIMER_PROF -This timer counts down against the total (i.e., both user and system) -CPU time consumed by the process. -(The measurement includes CPU time consumed by all threads in the process.) -At each expiration, a -.B SIGPROF -signal is generated. -.IP -In conjunction with -.BR ITIMER_VIRTUAL , -this timer can be used to profile user and system CPU time -consumed by the process. -.P -A process has only one of each of the three types of timers. -.P -Timer values are defined by the following structures: -.P -.in +4n -.EX -struct itimerval { - struct timeval it_interval; /* Interval for periodic timer */ - struct timeval it_value; /* Time until next expiration */ -}; -\& -struct timeval { - time_t tv_sec; /* seconds */ - suseconds_t tv_usec; /* microseconds */ -}; -.EE -.in -.\" -.SS getitimer() -The function -.BR getitimer () -places the current value of the timer specified by -.I which -in the buffer pointed to by -.IR curr_value . -.P -The -.I it_value -substructure is populated with the amount of time remaining until -the next expiration of the specified timer. -This value changes as the timer counts down, and will be reset to -.I it_interval -when the timer expires. -If both fields of -.I it_value -are zero, then this timer is currently disarmed (inactive). -.P -The -.I it_interval -substructure is populated with the timer interval. -If both fields of -.I it_interval -are zero, then this is a single-shot timer (i.e., it expires just once). -.SS setitimer() -The function -.BR setitimer () -arms or disarms the timer specified by -.IR which , -by setting the timer to the value specified by -.IR new_value . -If -.I old_value -is non-NULL, -the buffer it points to is used to return the previous value of the timer -(i.e., the same information that is returned by -.BR getitimer ()). -.P -If either field in -.I new_value.it_value -is nonzero, -then the timer is armed to initially expire at the specified time. -If both fields in -.I new_value.it_value -are zero, then the timer is disarmed. -.P -The -.I new_value.it_interval -field specifies the new interval for the timer; -if both of its subfields are zero, the timer is single-shot. -.SH RETURN VALUE -On success, zero is returned. -On error, \-1 is returned, and -.I errno -is set to indicate the error. -.SH ERRORS -.TP -.B EFAULT -.IR new_value , -.IR old_value , -or -.I curr_value -is not valid a pointer. -.TP -.B EINVAL -.I which -is not one of -.BR ITIMER_REAL , -.BR ITIMER_VIRTUAL , -or -.BR ITIMER_PROF ; -or (since Linux 2.6.22) one of the -.I tv_usec -fields in the structure pointed to by -.I new_value -contains a value outside the range [0, 999999]. -.SH VERSIONS -The standards are silent on the meaning of the call: -.P -.in +4n -.EX -setitimer(which, NULL, &old_value); -.EE -.in -.P -Many systems (Solaris, the BSDs, and perhaps others) -treat this as equivalent to: -.P -.in +4n -.EX -getitimer(which, &old_value); -.EE -.in -.P -In Linux, this is treated as being equivalent to a call in which the -.I new_value -fields are zero; that is, the timer is disabled. -.IR "Don't use this Linux misfeature" : -it is nonportable and unnecessary. -.SH STANDARDS -POSIX.1-2008. -.SH HISTORY -POSIX.1-2001, SVr4, 4.4BSD (this call first appeared in 4.2BSD). -POSIX.1-2008 marks -.BR getitimer () -and -.BR setitimer () -obsolete, recommending the use of the POSIX timers API -.RB ( timer_gettime (2), -.BR timer_settime (2), -etc.) instead. -.SH NOTES -Timers will never expire before the requested time, -but may expire some (short) time afterward, which depends -on the system timer resolution and on the system load; see -.BR time (7). -(But see BUGS below.) -If the timer expires while the process is active (always true for -.BR ITIMER_VIRTUAL ), -the signal will be delivered immediately when generated. -.P -A child created via -.BR fork (2) -does not inherit its parent's interval timers. -Interval timers are preserved across an -.BR execve (2). -.P -POSIX.1 leaves the -interaction between -.BR setitimer () -and the three interfaces -.BR alarm (2), -.BR sleep (3), -and -.BR usleep (3) -unspecified. -.SH BUGS -The generation and delivery of a signal are distinct, and -only one instance of each of the signals listed above may be pending -for a process. -Under very heavy loading, an -.B ITIMER_REAL -timer may expire before the signal from a previous expiration -has been delivered. -The second signal in such an event will be lost. -.P -Before Linux 2.6.16, timer values are represented in jiffies. -If a request is made set a timer with a value whose jiffies -representation exceeds -.B MAX_SEC_IN_JIFFIES -(defined in -.IR include/linux/jiffies.h ), -then the timer is silently truncated to this ceiling value. -On Linux/i386 (where, since Linux 2.6.13, -the default jiffy is 0.004 seconds), -this means that the ceiling value for a timer is -approximately 99.42 days. -Since Linux 2.6.16, -the kernel uses a different internal representation for times, -and this ceiling is removed. -.P -On certain systems (including i386), -Linux kernels before Linux 2.6.12 have a bug which will produce -premature timer expirations of up to one jiffy under some circumstances. -This bug is fixed in Linux 2.6.12. -.\" 4 Jul 2005: It looks like this bug may remain in Linux 2.4.x. -.\" http://lkml.org/lkml/2005/7/1/165 -.P -POSIX.1-2001 says that -.BR setitimer () -should fail if a -.I tv_usec -value is specified that is outside of the range [0, 999999]. -However, up to and including Linux 2.6.21, -Linux does not give an error, but instead silently -adjusts the corresponding seconds value for the timer. -From Linux 2.6.22 onward, -this nonconformance has been repaired: -an improper -.I tv_usec -value results in an -.B EINVAL -error. -.\" Bugzilla report 25 Apr 2006: -.\" http://bugzilla.kernel.org/show_bug.cgi?id=6443 -.\" "setitimer() should reject noncanonical arguments" -.SH SEE ALSO -.BR gettimeofday (2), -.BR sigaction (2), -.BR signal (2), -.BR timer_create (2), -.BR timerfd_create (2), -.BR time (7) |