s390_runtime_instr(2) — Linux manual page


s390_runtime_instr(2)      System Calls Manual     s390_runtime_instr(2)

NAME         top

       s390_runtime_instr - enable/disable s390 CPU run-time

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #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         top

       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         top

       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.

ERRORS         top

       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.

              The run-time instrumentation facility is not available.

STANDARDS         top

       Linux on s390.

HISTORY         top

       Linux 3.7.  System z EC12.

NOTES         top

       The asm/runtime_instr.h header file is available since Linux

       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         top

       syscall(2), signal(7)

Linux man-pages (unreleased)     (date)            s390_runtime_instr(2)

Pages that refer to this page: syscalls(2)