[buraktamturk]

I am not sure about Linux kernel internals and I/O operations. However, on Windows kernel the filesystem (or any driver incl. networking) can complete an I/O operation in non-blocking way, it just marks the IRP (descriptor for I/O operation) is pending and complete it later in different context (i.e. in an interrupt handler even when it is in different process/thread context). Since the user mode application can wait for multiple different kind of objects at the same time (this includes networking, file, mutexes, events), I guess in theory it can really scale when thread_count = core_count.