S390_RUNTIME_INSTR
Section: System Calls (2)
Updated: 2020-06-09
Page Index
NAME
s390_runtime_instr - enable/disable s390 CPU run-time instrumentation
SYNOPSIS
#include <asm/runtime_instr.h>
int s390_runtime_instr(int command, int signum);
DESCRIPTION
The
s390_runtime_instr()
system call starts or stops CPU run-time instrumentation for the
calling thread.
The
command
argument controls whether run-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 real-time signal.
This argument was used to specify a signal number that should be delivered
to the thread if the run-time instrumentation buffer was full or if
the run-time-instrumentation-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
run-time instrumentation by assigning the thread a default run-time
instrumentation control block.
The caller can then read and modify the control block and start the run-time
instrumentation.
On error, -1 is returned and
errno
is set to one of the error codes listed below.
ERRORS
- EINVAL
-
The value specified in
command
is not a valid command.
- EINVAL
-
The value specified in
signum
is not a real-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 run-time instrumentation control block failed.
- EOPNOTSUPP
-
The run-time instrumentation facility is not available.
VERSIONS
This system call is available since Linux 3.7.
CONFORMING TO
This Linux-specific system call is available only on the s390 architecture.
The run-time instrumentation facility is available
beginning with System z EC12.
NOTES
Glibc does not provide a wrapper for this system call, use
syscall(2)
to call it.
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 real-time signal.
For backwards compatibility with older kernels, it is recommended to pass
a valid real-time signal number in
signum
and install a handler for that signal.
SEE ALSO
syscall(2),
signal(7)
COLOPHON
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