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.
The value specified in command is not a valid command.
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.
Allocating memory for the run-time instrumentation control block failed.
The run-time instrumentation facility is not available.
Linux on s390.
Linux 3.7. 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.