Function rcudnn::cudaDeviceSetLimit[−][src]

pub unsafe extern "C" fn cudaDeviceSetLimit(
    limit: cudaLimit, 
    value: usize
) -> cudaError
Expand description

\brief Set resource limits

Setting \p limit to \p value is a request by the application to update the current limit maintained by the device. The driver is free to modify the requested value to meet h/w requirements (this could be clamping to minimum or maximum values, rounding up to nearest element size, etc). The application can use ::cudaDeviceGetLimit() to find out exactly what the limit has been set to.

Setting each ::cudaLimit has its own specific restrictions, so each is discussed here.

  • ::cudaLimitStackSize controls the stack size in bytes of each GPU thread.

  • ::cudaLimitPrintfFifoSize controls the size in bytes of the shared FIFO used by the ::printf() device system call. Setting ::cudaLimitPrintfFifoSize must not be performed after launching any kernel that uses the ::printf() device system call - in such case ::cudaErrorInvalidValue will be returned.

  • ::cudaLimitMallocHeapSize controls the size in bytes of the heap used by the ::malloc() and ::free() device system calls. Setting ::cudaLimitMallocHeapSize must not be performed after launching any kernel that uses the ::malloc() or ::free() device system calls - in such case ::cudaErrorInvalidValue will be returned.

  • ::cudaLimitDevRuntimeSyncDepth controls the maximum nesting depth of a grid at which a thread can safely call ::cudaDeviceSynchronize(). Setting this limit must be performed before any launch of a kernel that uses the device runtime and calls ::cudaDeviceSynchronize() above the default sync depth, two levels of grids. Calls to ::cudaDeviceSynchronize() will fail with error code ::cudaErrorSyncDepthExceeded if the limitation is violated. This limit can be set smaller than the default or up the maximum launch depth of 24. When setting this limit, keep in mind that additional levels of sync depth require the runtime to reserve large amounts of device memory which can no longer be used for user allocations. If these reservations of device memory fail, ::cudaDeviceSetLimit will return ::cudaErrorMemoryAllocation, and the limit can be reset to a lower value. This limit is only applicable to devices of compute capability 3.5 and higher. Attempting to set this limit on devices of compute capability less than 3.5 will result in the error ::cudaErrorUnsupportedLimit being returned.

  • ::cudaLimitDevRuntimePendingLaunchCount controls the maximum number of outstanding device runtime launches that can be made from the current device. A grid is outstanding from the point of launch up until the grid is known to have been completed. Device runtime launches which violate this limitation fail and return ::cudaErrorLaunchPendingCountExceeded when ::cudaGetLastError() is called after launch. If more pending launches than the default (2048 launches) are needed for a module using the device runtime, this limit can be increased. Keep in mind that being able to sustain additional pending launches will require the runtime to reserve larger amounts of device memory upfront which can no longer be used for allocations. If these reservations fail, ::cudaDeviceSetLimit will return ::cudaErrorMemoryAllocation, and the limit can be reset to a lower value. This limit is only applicable to devices of compute capability 3.5 and higher. Attempting to set this limit on devices of compute capability less than 3.5 will result in the error ::cudaErrorUnsupportedLimit being returned.

  • ::cudaLimitMaxL2FetchGranularity controls the L2 cache fetch granularity. Values can range from 0B to 128B. This is purely a performance hint and it can be ignored or clamped depending on the platform.

  • ::cudaLimitPersistingL2CacheSize controls size in bytes available for persisting L2 cache. This is purely a performance hint and it can be ignored or clamped depending on the platform.

\param limit - Limit to set \param value - Size of limit

\return ::cudaSuccess, ::cudaErrorUnsupportedLimit, ::cudaErrorInvalidValue, ::cudaErrorMemoryAllocation \notefnerr \note_init_rt \note_callback

\sa ::cudaDeviceGetLimit, ::cuCtxSetLimit