[LU-15194] fix unusual readahead window behavior with single page reads

Wed, 3 Nov 2021 22:10:52 +0000

Readahead has a bit of odd behavior with single page reads. The first page read does not cause the readahead code to be called, so it doesn't learn the actual RPC size data.

That means if the first read is a single page read and the next read triggers readahead, the size of the readahead is MAX_BRW_PAGES - so the readahead window is set to 64 MiB, even if the RPC size is set to 1 MiB or 4 MiB!

Whamcloud Community JIRA

[LU-15194] fix unusual readahead window behavior with single page reads