What posix_fadvise() args for sequential file write?

Question

I am working on an application which does sequentially write a large file (and does not read at all), and I would like to use posix_fadvise() to optimize the filesy

Answer 1

As far as writes go I think that you can just rely on the OSes disk IO scheduler to do the right thing.

You should keep in mind that while posix_fadvise is there specifically to give the kernel hints about future file usage patterns the kernel also has other data to help it out.

If you don't open the file for reading then it would only need to read blocks in when they were partially written. If you were to truncate the file to 0 then it doesn't even have to do that (you said that you were overwriting).