Manpage of SPU_CREATE
SPU_CREATESection: Linux Programmer's Manual (2)
NAMEspu_create - create a new spu context
#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);
DESCRIPTIONThe 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 pathnameand returns a file descriptor associated with it. pathnamemust refer to a nonexistent directory in the mount point of the SPU filesystem (spufs). If spu_create() is successful, a directory is created at pathnameand 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 dirfdargument to the *atfamily 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 pathnamedirectory) once the last reference to the context has gone; this usually occurs when the file descriptor returned by spu_create() is closed.
The flagsargument can be zero or any bitwise OR-ed combination of the following constants:
- Rather than using signals for reporting DMA errors, use the eventargument to spu_run(2).
- 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 pathnameargument. 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().
- 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_NOSCHEDcontexts. Only a subset of the files will be available in this context directory in spufs. Additionally, SPU_CREATE_NOSCHEDcontexts cannot dump a core file when crashing.
Creating SPU_CREATE_NOSCHEDcontexts requires the CAP_SYS_NICEcapability.
- Create an isolated SPU context.
Isolated contexts are protected from some
PPE (PowerPC Processing Element)
such as access to the SPU local store and the NPC register.
Creating SPU_CREATE_ISOLATEcontexts also requires the SPU_CREATE_NOSCHEDflag.
- 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_fdargument.
- Create a context with affinity to system memory. This affinity information is used within the SPU scheduling algorithm.
RETURN VALUEOn success, spu_create() returns a new file descriptor. On error, -1 is returned, and errnois set to one of the error codes listed below.
- The current user does not have write access to the spufs(7) mount point.
- An SPU context already exists at the given pathname.
- pathnameis not a valid string pointer in the calling process's address space.
- pathnameis not a directory in the spufs(7) mount point, or invalid flags have been provided.
- Too many symbolic links were found while resolving pathname.
- The per-process limit on the number of open file descriptors has been reached.
- pathnameis too long.
- The system-wide limit on the total number of open files has been reached.
- An isolated context was requested, but the hardware does not support SPU isolation.
- Part of pathnamecould not be resolved.
- The kernel could not allocate all resources required.
- 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.
- The functionality is not provided by the current system, because either the hardware does not provide SPUs or the spufs module is not loaded.
- A part of pathnameis not a directory.
- The SPU_CREATE_NOSCHEDflag has been given, but the user does not have the CAP_SYS_NICEcapability.
FILESpathnamemust point to a location beneath the mount point of spufs. By convention, it gets mounted in /spu.
VERSIONSThe spu_create() system call was added to Linux in kernel 2.6.16.
CONFORMING TOThis call is Linux-specific and implemented only on the PowerPC architecture. Programs using this system call are not portable.
NOTESGlibc 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 for the recommended libraries.
EXAMPLESee spu_run(2) for an example of the use of spu_create()
SEE ALSOclose(2), spu_run(2), capabilities(7), spufs(7)
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