I am currently working on a project which is related to the operation of the linux readahead prefetcher. As a result, I am trying to understand its operation. Having read thoroughly the relevant part in the kernel code, I realize, from the comments, that part of the prefetching occurs asynchronously. The problem is that I can not verify this from the code.

Even if you call page_cache_sync_readahead() or page_cache_async_readahead(), then both will end up in ra_submit(), in which, the operation is common for both cases.

So, please could you tell me at which point does the operation of prefetching occurs asynchronously?

Thank you in advance,

Vasilis Dimitsas