#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 non-existing 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
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 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 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()
This page is part of release 3.14 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/.
