On 30 Nov 2022, at 15:13, Hannes Mehnert <hannes@xxxxxxxxxxx> wrote:
## `mmap` available on `Mirage_block.S` (dinosaure, https://github.com/mirage/mirage-block/issues/53)- dinosaure has an implementation to get a part of the block (similar to mmap), without being in the Lwt monad- at the moment, read is in Lwt.t, i.e. does not block, but returns the filled page(s)- dinosaure needs a blocking function that returns the data- the solo5 interface is already blocking (and synchronous), mirage-block-solo5 adds the asynchronous stuff- christiano mentions that it could be done with locking- maybe develop a block read-only interface with a synchronous read
In general, having "automatic" scheduling via mmap is a bad idea for anything non-trivial, since you slow to a crawl when under memory pressure and having a lot of page faults. There's no way a caller can determine whether or not a set of accesses will result in a blocking fetch or not.
It may be workable for a read-only mmap, but... why do you want it? To get out of Lwt allocations?
Anil |
