HOSTVISIBLE

Hostvisible refers to memory regions that can be directly addressed by the host CPU. In contrast to device-local memory used by accelerators or GPUs, hostvisible memory can be accessed by software running on the host without going through device DMA or extra copies. Such memory is typically allocated from pools that are pinned or otherwise made resident and may be mapped into the host's virtual address space for reading and writing.

In low-level graphics and compute interfaces, memory blocks exposed to the host include a host-visible property. For example, APIs like Vulkan define memory type flags such as HOST_VISIBLE to indicate that a memory block can be mapped to a host address space. Some extensions also offer host-coherent semantics, ensuring that writes performed by the host are visible to device accesses without explicit flushes, while write-combined or cached variants may require explicit synchronization.

Usage and trade-offs: Hostvisible memory is often used for staging buffers, dynamic resources, or zero-copy data transfers between the CPU and device. It enables the host to prepare data without staging copies. The trade-offs include potential lower bandwidth, higher latency, or the need to synchronize caches; device-local memory can offer higher throughput and is better for long-lived data.

In practice, developers choose hostvisible allocations when they require fast CPU-to-device data exchange or dynamic content, balancing performance and convenience.