s390_runtime_instr - enable/disable s390 CPU run-time instrumentation
Standard C library (
libc,
-lc)
#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).
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.
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 indicate the error.
- 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.
This system call is available since Linux 3.7.
This Linux-specific system call is available only on the s390 architecture. The
run-time instrumentation facility is available beginning with System z EC12.
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.
syscall(2),
signal(7)