NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | FILES | VERSIONS | CONFORMING TO | NOTES | EXAMPLE | 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 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 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
              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
              Create a context with affinity to system memory.  This
              affinity information is used within the SPU scheduling
              algorithm.

       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.

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 recom‐
       mended libraries.

EXAMPLE         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 4.07 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                            2015-12-28                    SPU_CREATE(2)