On Wed, Jun 02, 2021 at 04:54:26PM +0800, Jason Wang wrote: > > 在 2021/6/2 上午1:31, Jason Gunthorpe 写道: > > On Tue, Jun 01, 2021 at 04:47:15PM +0800, Jason Wang wrote: > > > We can open up to ~0U file descriptors, I don't see why we need to restrict > > > it in uAPI. > > There are significant problems with such large file descriptor > > tables. High FD numbers man things like select don't work at all > > anymore and IIRC there are more complications. > > > I don't see how much difference for IOASID and other type of fds. People can > choose to use poll or epoll. Not really, once one thing in an applicate uses a large number FDs the entire application is effected. If any open() can return 'very big number' then nothing in the process is allowed to ever use select. It is not a trivial thing to ask for > And with the current proposal, (assuming there's a N:1 ioasid to ioasid). I > wonder how select can work for the specific ioasid. pagefault events are one thing that comes to mind. Bundling them all together into a single ring buffer is going to be necessary. Multifds just complicate this too Jason
