On Tue, Feb 08, 2022 at 01:10:33PM -0600, Nick Neumann wrote: > I'm learning about io_submit_mode and avoiding the coordinated > omission problem. The fio docs cover the mode and give two examples of > using it. But there is a comment in the docs that says > > "Note that this option cannot reliably be used with async IO engines." > > I don't really understand why? Further, both examples in the docs of > using the option specify the libaio engine, which is asynchronous, > adding to my confusion. > > Perhaps the comment means to say "sync" and not "async" - I could see > how pushing I/O to a pool of threads in the sync case could be odd, > but not necessarily "unreliable", so maybe not. Just trying to > understand what danger the comment is trying to warn of. Original commit disallowed offload for all async ioengines: https://git.kernel.dk/cgit/fio/commit/?id=abfd235a05330eae8444f0e4c0039bbdf9f160a3 Later it was changed to be disallowed only for io_uring: https://git.kernel.dk/cgit/fio/commit/?id=8bfe330eb42739d503d35d0b7d96f98c5c544204 So I assume that offload works fine with libaio. Perhaps the HOWTO, man page, and the comment in check_engine_ops() should simply be updated? Kind regards, Niklas
