spu_create(2) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | FILES | VERSIONS | CONFORMING TO | NOTES | EXAMPLES | SEE ALSO | COLOPHON

SPU_CREATE(2)           Linux Programmer's Manual          SPU_CREATE(2)

NAME         top

       spu_create - create a new spu context

SYNOPSIS         top

       #include <sys/types.h>
       #include <sys/spu.h>

       int spu_create(const char *pathname, int flags, mode_t mode,
                      int neighbor_fd);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION         top

       The spu_create() system call is used on PowerPC machines that
       implement the Cell Broadband Engine Architecture in order to
       access Synergistic Processor Units (SPUs).  It creates a new
       logical context for an SPU in pathname and returns a file
       descriptor associated with it.  pathname must refer to a
       nonexistent directory in the mount point of the SPU filesystem
       (spufs).  If spu_create() is successful, a directory is created
       at pathname and it is populated with the files described in
       spufs(7).

       When a context is created, the returned file descriptor can only
       be passed to spu_run(2), used as the dirfd argument to the *at
       family of system calls (e.g., openat(2)), or closed; other
       operations are not defined.  A logical SPU context is destroyed
       (along with all files created within the context's pathname
       directory) once the last reference to the context has gone; this
       usually occurs when the file descriptor returned by spu_create()
       is closed.

       The mode argument (minus any bits set in the process's umask(2))
       specifies the permissions used for creating the new directory in
       spufs.  See stat(2) for a full list of the possible mode values.

       The neighbor_fd is used only when the SPU_CREATE_AFFINITY_SPU
       flag is specified; see below.

       The flags argument can be zero or any bitwise OR-ed combination
       of the following constants:

       SPU_CREATE_EVENTS_ENABLED
              Rather than using signals for reporting DMA errors, use
              the event argument to spu_run(2).

       SPU_CREATE_GANG
              Create an SPU gang instead of a context.  (A gang is a
              group of SPU contexts that are functionally related to
              each other and which share common scheduling parameters—
              priority and policy.  In the future, gang scheduling may
              be implemented causing the group to be switched in and out
              as a single unit.)

              A new directory will be created at the location specified
              by the pathname argument.  This gang may be used to hold
              other SPU contexts, by providing a pathname that is within
              the gang directory to further calls to spu_create().

       SPU_CREATE_NOSCHED
              Create a context that is not affected by the SPU
              scheduler.  Once the context is run, it will not be
              scheduled out until it is destroyed by the creating
              process.

              Because the context cannot be removed from the SPU, some
              functionality is disabled for SPU_CREATE_NOSCHED contexts.
              Only a subset of the files will be available in this
              context directory in spufs.  Additionally,
              SPU_CREATE_NOSCHED contexts cannot dump a core file when
              crashing.

              Creating SPU_CREATE_NOSCHED contexts requires the
              CAP_SYS_NICE capability.

       SPU_CREATE_ISOLATE
              Create an isolated SPU context.  Isolated contexts are
              protected from some PPE (PowerPC Processing Element)
              operations, such as access to the SPU local store and the
              NPC register.

              Creating SPU_CREATE_ISOLATE contexts also requires the
              SPU_CREATE_NOSCHED flag.

       SPU_CREATE_AFFINITY_SPU (since Linux 2.6.23)
              Create a context with affinity to another SPU context.
              This affinity information is used within the SPU
              scheduling algorithm.  Using this flag requires that a
              file descriptor referring to the other SPU context be
              passed in the neighbor_fd argument.

       SPU_CREATE_AFFINITY_MEM (since Linux 2.6.23)
              Create a context with affinity to system memory.  This
              affinity information is used within the SPU scheduling
              algorithm.

RETURN VALUE         top

       On success, spu_create() returns a new file descriptor.  On
       error, -1 is returned, and errno is set to one of the error codes
       listed below.

ERRORS         top

       EACCES The current user does not have write access to the
              spufs(7) mount point.

       EEXIST An SPU context already exists at the given pathname.

       EFAULT pathname is not a valid string pointer in the calling
              process's address space.

       EINVAL pathname is not a directory in the spufs(7) mount point,
              or invalid flags have been provided.

       ELOOP  Too many symbolic links were found while resolving
              pathname.

       EMFILE The per-process limit on the number of open file
              descriptors has been reached.

       ENAMETOOLONG
              pathname is too long.

       ENFILE The system-wide limit on the total number of open files
              has been reached.

       ENODEV An isolated context was requested, but the hardware does
              not support SPU isolation.

       ENOENT Part of pathname could not be resolved.

       ENOMEM The kernel could not allocate all resources required.

       ENOSPC There are not enough SPU resources available to create a
              new context or the user-specific limit for the number of
              SPU contexts has been reached.

       ENOSYS The functionality is not provided by the current system,
              because either the hardware does not provide SPUs or the
              spufs module is not loaded.

       ENOTDIR
              A part of pathname is not a directory.

       EPERM  The SPU_CREATE_NOSCHED flag has been given, but the user
              does not have the CAP_SYS_NICE capability.

FILES         top

       pathname must point to a location beneath the mount point of
       spufs.  By convention, it gets mounted in /spu.

VERSIONS         top

       The spu_create() system call was added to Linux in kernel 2.6.16.

CONFORMING TO         top

       This call is Linux-specific and implemented only on the PowerPC
       architecture.  Programs using this system call are not portable.

NOTES         top

       Glibc does not provide a wrapper for this system call; call it
       using syscall(2).  Note however, that spu_create() is meant to be
       used from libraries that implement a more abstract interface to
       SPUs, not to be used from regular applications.  See 
       ⟨http://www.bsc.es/projects/deepcomputing/linuxoncell/⟩ for the
       recommended libraries.

       Prior to the addition of the SPU_CREATE_AFFINITY_SPU flag in
       Linux 2.6.23, the spu_create() system call took only three
       arguments (i.e., there was no neighbor_fd argument).

EXAMPLES         top

       See spu_run(2) for an example of the use of spu_create()

SEE ALSO         top

       close(2), spu_run(2), capabilities(7), spufs(7)

COLOPHON         top

       This page is part of release 5.10 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.

Linux                          2020-12-21                  SPU_CREATE(2)

Pages that refer to this page: spu_run(2)syscalls(2)spufs(7)