Hi, I am writing a block device driver and i am using the 'blq_queue_make_request' call while registering my block device driver. Now as far as i understand this will bypass the linux kernel queue for each block device driver (bypassing the elevator algorithm etc). However, i am still not very clear about exactly how i get a request. 1. Consider i am doing a dd on the block device directly : Will it bypass the buffer cache(/page cache) or will it use it. Example if i register my block device with set_blocksize() as 512. And i do a dd of 512 bytes will i get a read because it passes through the buffer cache and since the minimum page size is 4096 it has to read the page first and then pass it to me. I am still unclear about the 'page' in the bvec. What does that refer to? Is it a page from the page cache or a user buffer (DMA). 2. Another thing i am not clear about is a queue. When i register my driver, the 'make_request' function gets called whenever there is an io. Now in my device driver, i have some more logic about writing this io i.e some time may be spent in the device driver for each io. In such a case, if i get two ios on the same block one after the other (say one is writing 'a' and the other is writing 'b') then isn't it possible that i may end up passing 'b' followed by 'a' to the layer below me (changing the order because thread 'a' took more time than thread 'b'). Then in that case should i be using a queue in my layer - put the ios in the queue whenever i get a call to 'make_request'. Another thread keeps pulling the ios from the queue and processing them and passing it to the layer below. Regards, Neha