File buffer.h¶
This file contains the interface definition for the backends.
For normal use you should not call the functions defined in this file directly.
See also
array.h For managing buffers
See also
kernel.h For using kernels
Typedefs
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typedef struct _gpucontext gpucontext¶
Opaque struct for context data.
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typedef struct _gpucontext_props gpucontext_props¶
Opaque structure that holds properties for the context.
Enums
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enum ga_usefl¶
Flags for gpukernel_init().
It is important to specify these properly as the compilation machinery will ensure that the proper configuration is made to support the requested features or error out if the demands cannot be met.
Warning
Failure to properly specify the feature flags will in most cases result in silent data corruption (especially on ATI cards).
Values:
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enumerator GA_USE_SMALL¶
The kernel makes use of small (size is smaller than 4 bytes) types.
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enumerator GA_USE_DOUBLE¶
The kernel makes use of double or complex doubles.
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enumerator GA_USE_COMPLEX¶
The kernel makes use of complex of complex doubles.
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enumerator GA_USE_HALF¶
The kernel makes use of half-floats (also known as float16)
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enumerator GA_USE_CUDA¶
The kernel is made of CUDA code.
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enumerator GA_USE_OPENCL¶
The kernel is made of OpenCL code.
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enumerator GA_USE_SMALL¶
Functions
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int gpu_get_platform_count(const char *name, unsigned int *platcount)¶
Gets information about the number of available platforms for the backend specified in
name
.- Parameters:
name – the backend name
platcount – will contain number of compatible platforms in host
- Returns:
GA_NO_ERROR, if success
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int gpu_get_device_count(const char *name, unsigned int platform, unsigned int *devcount)¶
Gets information about the number of compatible devices on a specific host’s
platform
for the backend specified inname
.- Parameters:
name – the backend name
platform – number for a platform in host
devcount – will contain number of compatible devices in
platform
- Returns:
GA_NO_ERROR, if success
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int gpucontext_props_new(gpucontext_props **res)¶
Allocate and initialized an instance of gpucontext_props.
Initialization is done with default values.
- Parameters:
res – pointer to storage space for the created object
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_cuda_dev(gpucontext_props *p, int devno)¶
Set the device number for a CUDA device.
- Parameters:
p – properties object
devno – device number
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_opencl_dev(gpucontext_props *p, int platno, int devno)¶
Set the platform and device for OpenCL.
- Parameters:
p – properties object
platno – platform number
devno – device number
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_sched(gpucontext_props *p, int sched)¶
Set the scheduling mode for the device.
- Parameters:
p – properties object
sched – scheduling mode. One of these.
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_set_single_stream(gpucontext_props *p)¶
Set single-stream mode.
All operations on the device will be serialized on a single stream. This will also disable most of the interlocking normally done between multiple streams to keep everything in order.
This mode can be faster if you don’t have a lot of device-level parallelism in your workload.
- Parameters:
p – properties object
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_kernel_cache(gpucontext_props *p, const char *path)¶
Set the path for the kernel cache.
The cache can be shared with other running instances, even on shared drives.
- Parameters:
p – properties object
path – desired location of the kernel cache
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_props_alloc_cache(gpucontext_props *p, size_t initial, size_t max)¶
Configure the allocation cache.
The maximum size is also a limit on the total amount of memory allocated on the device.
- Parameters:
p – properties object
initial – initial size of the cache
max – maximum size of the cache
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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void gpucontext_props_del(gpucontext_props *p)¶
Free a properties object.
This should not be called on a properties object that has been passed to gpucontext_init().
- Parameters:
p – properties object
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpucontext_init(gpucontext **res, const char *name, gpucontext_props *props)¶
Create a context on the specified device.
The passed-in properties pointer will be managed by this function and needs not be freed. This means that you shouldn’t touch the properties object after passing it to this function.
Warning
This function is not thread-safe.
- Parameters:
res – a pointer to a location that will be allocated
name – the backend name.
props – a properties object for the context. Can be NULL for defaults.
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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void gpucontext_deref(gpucontext *ctx)¶
Dereference a context.
This removes a reference to the context and as soon as the reference count drops to zero the context is destroyed. The context can stay alive after you call this function because some object keep a reference to their context.
- Parameters:
ctx – a valid context pointer.
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int gpucontext_property(gpucontext *ctx, int prop_id, void *res)¶
Fetch a context property.
The property must be a context property. The currently defined properties and their type are defined in Properties.
- Parameters:
ctx – context
prop_id – property id (from Properties)
res – pointer to the return space of the appropriate type
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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const char *gpucontext_error(gpucontext *ctx, int err)¶
Get a string describing
err
.If you need to get a description of a error that occurred during context creation, call this function using NULL as the context. This version of the call is not thread-safe.
- Parameters:
ctx – the context in which the error occured
err – error code
- Returns:
string description of error
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gpudata *gpudata_alloc(gpucontext *ctx, size_t sz, void *data, int flags, int *ret)¶
Allocates a buffer of size
sz
in contextctx
.Buffers are reference counted internally and start with a reference count of 1.
- Parameters:
ctx – a context pointer
sz – the requested size
flags – see Allocation flags
data – optional pointer to host buffer
ret – error return pointer
- Returns:
A non-NULL pointer to a gpudata structure. This structure is intentionally opaque as its content may change according to the backend used.
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void gpudata_retain(gpudata *b)¶
Increase the reference count to the passed buffer by 1.
- Parameters:
b – a buffer
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void gpudata_release(gpudata *b)¶
Release a buffer.
This will decrement the reference count of the buffer by 1. If that count reaches 0 all associated ressources will be released.
Even if your application does not have any references left to a buffer it may still hang around if it is in use by internal mechanisms (kernel call, …)
Check if two buffers may overlap.
Both buffers must have been created with the same backend.
- Parameters:
a – first buffer
b – second buffer
ret – error return pointer
- Return values:
1 – The buffers may overlap
0 – The buffers do not overlap.
-1 – An error was encoutered,
ret
contains a detailed error code if not NULL.
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int gpudata_move(gpudata *dst, size_t dstoff, gpudata *src, size_t srcoff, size_t sz)¶
Copy the content of a buffer to another.
Both buffers must be in the same context and contiguous. Additionally the buffers must not overlap otherwise the content of the destination buffer is not defined.
- Parameters:
dst – destination buffer
dstoff – offset inside the destination buffer
src – source buffer
srcoff – offset inside the source buffer
sz – size of data to copy (in bytes)
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpudata_transfer(gpudata *dst, size_t dstoff, gpudata *src, size_t srcoff, size_t sz)¶
Transfer the content of buffer across contexts.
If possible it will try to the the transfer in an efficient way using backend-specific tricks. If those fail or can’t be used, it will fallback to a copy through the host.
- Parameters:
dst – buffer to transfer to
dstoff – offset in the destination buffer
src – buffer to transfer from
srcoff – offset in the source buffer
sz – size of the region to transfer
- Returns:
the new buffer in dst_ctx or NULL if no efficient way to transfer could be found.
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int gpudata_read(void *dst, gpudata *src, size_t srcoff, size_t sz)¶
Transfer data from a buffer to memory.
The buffer and the memory region must be contiguous.
- Parameters:
dst – destination in memory
src – source buffer
srcoff – offset inside the source buffer
sz – size of data to copy (in bytes)
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpudata_write(gpudata *dst, size_t dstoff, const void *src, size_t sz)¶
Transfer data from memory to a buffer.
The buffer and the memory region must be contiguous.
- Parameters:
dst – destination buffer
dstoff – offset inside the destination buffer
src – source in memory
sz – size of data to copy (in bytes)
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpudata_memset(gpudata *dst, size_t dstoff, int data)¶
Set a buffer to a byte pattern.
This function acts like the C function memset() for device buffers.
- Parameters:
dst – destination buffer
dstoff – offset into the destination buffer
data – byte value to write into the destination.
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpudata_sync(gpudata *b)¶
Synchronize a buffer.
Waits for all previous read, writes, copies and kernel calls involving this buffer to be finished.
This call is not required for normal use of the library as all exposed operations will properly synchronize amongst themselves. This call may be useful in a performance timing context to ensure that the work is really done, or before interaction with another library to wait for pending operations.
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int gpudata_property(gpudata *buf, int prop_id, void *res)¶
Fetch a buffer property.
Can be used for buffer properties and context properties. Context properties will fetch the value for the context associated with the buffer. The currently defined properties and their type are defined in Properties.
- Parameters:
buf – buffer
prop_id – property id (from Properties)
res – pointer to the return space of the appropriate type
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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gpucontext *gpudata_context(gpudata *b)¶
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gpukernel *gpukernel_init(gpucontext *ctx, unsigned int count, const char **strings, const size_t *lengths, const char *fname, unsigned int numargs, const int *typecodes, int flags, int *ret, char **err_str)¶
Compile a kernel.
Compile the kernel composed of the concatenated strings in
strings
and return a callable kernel. If lengths is NULL then all the strings must be NUL-terminated. Otherwise, it doesn’t matter (but the lengths must not include the final NUL byte if provided).If
*err_str
is not NULL on return, the caller must callfree(*err_str)
after use.- Parameters:
ctx – context to work in
count – number of input strings
strings – table of string pointers
lengths – (optional) length for each string in the table
fname – name of the kernel function (as defined in the code)
numargs – number of kernel arguments
typecodes – the type of each argument
flags – flags for compilation (see ga_usefl)
ret – error return pointer
err_str – returns pointer to debug message from GPU backend (if provided a non-NULL err_str)
- Returns:
Allocated kernel structure or NULL if an error occured.
ret
will be updated with the error code if not NULL.
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void gpukernel_retain(gpukernel *k)¶
Retain a kernel.
Increase the reference count of the passed kernel by 1.
- Parameters:
k – a kernel
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void gpukernel_release(gpukernel *k)¶
Release a kernel.
Decrease the reference count of a kernel. If it reaches 0, all resources associated with
k
will be released.If the reference count of a kernel reaches 0 while it is running, this call will block until completion.
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int gpukernel_setarg(gpukernel *k, unsigned int i, void *a)¶
Set kernel argument.
Buffer arguments will not be retained and it is the responsability of the caller to ensure that the value is still valid whenever a call is made.
- Parameters:
k – kernel
i – argument index (starting at 0)
a – pointer to argument
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpukernel_call(gpukernel *k, unsigned int n, const size_t *gs, const size_t *ls, size_t shared, void **args)¶
Call a kernel.
If args is NULL, it will be assumed that the arguments have previously been set with kernel_setarg().
- Parameters:
k – kernel
n – number of dimensions of grid/block
gs – grid sizes for this call (also known as global size)
ls – block sizes for this call (also known as local size)
shared – amount of dynamic shared memory to reserve
args – table of pointers to each argument (optional).
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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int gpukernel_property(gpukernel *k, int prop_id, void *res)¶
Fetch a property.
Can be used for kernel and context properties. The context properties will fetch the value for the context associated with the kernel. The currently defined properties and their type are defined in Properties.
- Parameters:
k – kernel
prop_id – property id (from Properties)
res – pointer to the return space of the appropriate type
- Returns:
GA_NO_ERROR or an error code if an error occurred.
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gpucontext *gpukernel_context(gpukernel *k)¶