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

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 file system
       (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  con-
              texts.   Only  a subset of the files will be available in this context directory in spufs.  Additionally, SPU_CRE-
              ATE_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) opera-
              tions, 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 schedul-
              ing 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
       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 path name.

       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 process has reached its maximum open files limit.

       ENAMETOOLONG
              pathname is too long.

       ENFILE The system has reached the global open files limit.

       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 only implemented 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  applica-
       tions.  See http://www.bsc.es/projects/deepcomputing/linuxoncell/ for the recommended libraries.

EXAMPLE
       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 3.25 of the Linux man-pages project.  A description of the project, and information about
       reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.



Linux                                                      2007-12-20                                              SPU_CREATE(2)