Ubuntu Manpage: spu_create - create a new spu context

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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);

       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 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

       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 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.

EXAMPLE

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

COLOPHON

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       project,     and    information    about    reporting    bugs,    can    be    found    at
       http://www.kernel.org/doc/man-pages/.