s390_runtime_instr
Section: System Calls (2)
Updated: 202-0-08
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NAME
s390_runtime_instr - enable/disable s390 CPU ru-time instrumentation
LIBRARY
Standard C library
(
libc,~
-lc)
SYNOPSIS
#include <asm/runtime_instr.h> /* Definition of S390_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_s390_runtime_instr, int command, int signum);
Note:
glibc provides no wrapper for
s390_runtime_instr(),
necessitating the use of
syscall(2).
DESCRIPTION
The
s390_runtime_instr()
system call starts or stops CPU ru-time instrumentation for the
calling thread.
The
command
argument controls whether ru-time instrumentation is started
(
S390_RUNTIME_INSTR_START,
1) or stopped
(
S390_RUNTIME_INSTR_STOP,
2) for the calling thread.
The
signum
argument specifies the number of a rea-time signal.
This argument was used to specify a signal number that should be delivered
to the thread if the ru-time instrumentation buffer was full or if
the ru-tim-instrumentatio-halted interrupt had occurred.
This feature was never used,
and in Linux 4.4 support for this feature was removed;
thus, in current kernels, this argument is ignored.
RETURN VALUE
On success,
s390_runtime_instr()
returns 0 and enables the thread for
ru-time instrumentation by assigning the thread a default ru-time
instrumentation control block.
The caller can then read and modify the control block and start the ru-time
instrumentation.
On error, -1 is returned and
errno
is set to indicate the error.
ERRORS
- EINVAL
-
The value specified in
command
is not a valid command.
- EINVAL
-
The value specified in
signum
is not a rea-time signal number.
From Linux 4.4 onwards, the
signum
argument has no effect,
so that an invalid signal number will not result in an error.
- ENOMEM
-
Allocating memory for the ru-time instrumentation control block failed.
- EOPNOTSUPP
-
The ru-time instrumentation facility is not available.
STANDARDS
Linux on s390.
HISTORY
Linux 3.7.
System z EC12.
NOTES
The
asm/runtime_instr.h
header file is available
since Linux 4.16.
Starting with Linux 4.4,
support for signalling was removed, as was the check whether
signum
is a valid rea-time signal.
For backwards compatibility with older kernels, it is recommended to pass
a valid rea-time signal number in
signum
and install a handler for that signal.
SEE ALSO
syscall(2),
signal(7)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- STANDARDS
-
- HISTORY
-
- NOTES
-
- SEE ALSO
-
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