spu_create

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



NAME
       spu_create - create a new spu context

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

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

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

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

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

COLOPHON
       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)