blk_queue_chunk_sectors (9) - Linux Man Pages
blk_queue_chunk_sectors: set size of the chunk for this queue
blk_queue_chunk_sectors - set size of the chunk for this queue
void blk_queue_chunk_sectors(struct request_queue
*q, unsigned int chunk_sectors);
- the request queue for the device
- chunk sectors in the usual 512b unit
If a driver doesn't want IOs to cross a given chunk size, it can set this limit and prevent merging across chunks. Note that the chunk size must currently be a power-of-2 in sectors. Also note that the block layer must accept a page worth of data at any offset. So if the crossing of chunks is a hard limitation in the driver, it must still be prepared to split single page bios.