Environment variables

The rocBLAS environment variables are collected in the following tables.

Environment variable	Default value	Links	Value
ROCBLAS_USE_HIPBLASLT Provides manual control over which GEMM backend is used.	Unset by default.	Control the GEMM backend	Unset: GEMM backend is automatically selected. 0: Tensile is always used as the GEMM backend. 1: hipBLASLt is preferred as the GEMM backend, but will fallback to Tensile on problems for which hipBLASLt does not provide a solution or when errors are encountered using the hipBLASLt backend.
ROCBLAS_USE_HIPBLASLT_BATCHED Manual control to selectively disable the use of hipBlasLt only for the batched GEMMs. ROCBLAS_USE_HIPBLASLT=0 disables the ROCBLAS_USE_HIPBLASLT_BATCHED variable, because hipBlasLt would not be enabled.	1	Control the GEMM backend	Unset: GEMM batched default backend. 0: Tensile is always used as the GEMM batched backend. 1: hipBLASLt will be used as the GEMM batched backend when applicable, but will fallback to Tensile on problems for which hipBLASLt does not provide a solution or when errors are encountered using the hipBLASLt backend.
ROCBLAS_DEVICE_MEMORY_SIZE Sets how much memory to preallocate.	Unset by default.	Environment variable for preallocating memory	0 or unset: Lets rocBLAS manage the device memory. Bigger than 0: Sets the default handle device memory size to the specified size (in bytes).
ROCBLAS_DEFAULT_ATOMICS_MODE Sets the default atomics mode during the creation of rocblas_handle.	Unset by default.	Atomic operations	0: Sets the default to rocblas_atomics_not_allowed 1: Sets the default to rocblas_atomics_allowed
ROCBLAS_STREAM_ORDER_ALLOC Allows memory allocation and deallocation to be stream ordered.	0	Stream-ordered memory allocation	0: Disable 1: Enable
ROCBLAS_BENCH_STREAM_SYNC Benchmark timing based on hipStreamSynchronize, otherwise uses default hipEvent_t based timing.	0	rocblas-bench timing	0: Disable 1: Enable

Logging environment variables

The logging environment variables in rocBLAS are collected in the following table. For information on how to use these variables, see rocBLAS logging.