In article <[EMAIL PROTECTED]>, Paul Rubin <http://[EMAIL PROTECTED]> wrote:
> Select blocks until the data is ready, while with AIO the i/o happens > completely in the background and your process gets an interrupt when > the i/o completes. Also, with select based i/o, usually the kernel > reads data from the external device into a system buffer, and then you > do a read system call that copies the data from the system buffer to > your buffer. AIO can be set up so the i/o happens directly into your > buffer, avoiding the extra copying. You can also initiate a bunch of > different i/o events with a single system call, avoiding some context > switches. > > http://www.ibm.com/developerworks/linux/library/l-async/ > > describes select as "asynchronous, blocking" as opposed to AIO which > is asynchronous and nonblocking. Other descriptions I've seen reserve > "asynchronous i/o" for AIO-like schemes. It's just a terminological > thing. kqueue(2) on MacOS X mentions an EVFILT_AIO option. It isn't supported on that platform, but maybe that's a vestige of some other platform that does support "asynchronous, blocking" with aio -- as VAX/VMS did (and presumably still does), with event flags. Donn Cave, [EMAIL PROTECTED] -- http://mail.python.org/mailman/listinfo/python-list
