создать новый контекст spu (create a new spu context)
Имя (Name)
spu_create - create a new spu context
Синопсис (Synopsis)
#include <sys/spu.h> /* Definition of SPU_* constants */
#include <sys/syscall.h> /* Definition of SYS_* constants */
#include <unistd.h>
int syscall(SYS_spu_create, const char *pathname, unsigned int flags,
mode_t mode, int neighbor_fd);
Note: glibc provides no wrapper for spu_create(), necessitating
the use of syscall(2).
Описание (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.
Возвращаемое значение (Return value)
On success, spu_create() returns a new file descriptor. On
failure, -1 is returned, and errno is set to indicate the error.
Ошибки (Error)
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.
Файлы (Files)
pathname must point to a location beneath the mount point of
spufs. By convention, it gets mounted in /spu.
Версии (Versions)
The spu_create() system call was added to Linux in kernel 2.6.16.
Стандарты (Conforming to)
This call is Linux-specific and implemented only on the PowerPC
architecture. Programs using this system call are not portable.
Примечание (Note)
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).
Примеры (Examples)
See spu_run(2) for an example of the use of spu_create()
Смотри также (See also)
close(2), spu_run(2), capabilities(7), spufs(7)
