Re: [take21 0/4] kevent: Generic event handling mechanism.

From: Jeff Garzik
Date: Tue Nov 07 2006 - 06:47:32 EST


At an aside... This may be useful. Or not.

Al Viro had an interesting idea about kernel<->userspace data passing interfaces. He had suggested creating a task-specific filesystem derived from ramfs. Through the normal VFS/VM codepaths, the user can easily create [subject to resource/priv checks] a buffer that is locked into the pagecache. Using mmap, read, write, whatever they prefer. Derive from tmpfs, and the buffers are swappable.

Then it would be a simple matter to associate a file stored in "keventfs" with a ring buffer guaranteed to be pagecache-friendly.

Heck, that might make zero-copy easier in some cases, too. And using a filesystem would mean that you could do all this without adding syscalls, by using special (poll-able!) files in the filesystem for control and notification purposes.

Jeff



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