On 2012-10-16 19:15, Benjamin LaHaise wrote: > On Tue, Oct 16, 2012 at 10:00:54AM -0700, Zach Brown wrote: >>> Not all IOs will complete within a bounded amount of time. Think of things >>> like pipes, network send/receive, even the USB gadget code. >> >> Yes, I know. That's the theoretical position. >> >> But reality doesn't match that view. People aren't using it. If the > > But that's an issue of the lack of support for the functionality. The > kernel doesn't implement the functionality for 99.99% of file descriptors, > so of course it's not going to be used. If, as we were chatting about, > other uses can be made possible by using a thread pool or some as yet > undecided approach, it will be required. > > Let's address the lack of support issue before deprecating required parts > of the API. Or make the case to rip everything out. Come on, this has been the case for, what, 10 years? Or for however long that we've had this aio interface. I'd be happy just bypassing the cancel, in fact I did just that to actually make aio scale to any extent at all. But using the lack of a support as an argument to keep that interface is just a non-starter to begin with. It's clearly NEVER goint to get done. >> usb gadget code can do without then the actual users of aio can be made >> a wee bit faster without having to build cancel code without users to >> hammer on it. > > Gadget cannot. The code has no control over when a request completes. > Think of things like talking to a USB serial port or keyboard directly. > Afaik it is getting used for USB direct access in a number of cases, which > goes to show that if the functionality is implemented, people will use it. IMHO, just bypassing the cancel bits for things that don't implement it (that is, anything but usb gadget) is trivial. It's part of the lots of low hanging fruit in aio. -- Jens Axboe -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
