Messages in this thread |  | | From | Zach Brown <> | Subject | Re: [patch 05/11] syslets: core code | Date | Wed, 14 Feb 2007 18:52:46 -0800 |
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>> But the whole point is that the notion of a "register" is wrong in >> the >> first place. [...] > > forget about it then. The thing we "register" is dead-simple: > > struct async_head_user { > struct syslet_uatom __user **completion_ring; > unsigned long ring_size_bytes; > unsigned long max_nr_threads; > }; > > this can be passed in to sys_async_exec() as a second pointer, and the > kernel can put the expected-completion pointer (and the user ring idx > pointer) into its struct atom. It's just a few instructions, and > only in > the cachemiss case. > > that would make completions arbitrarily split-up-able. No registration > whatsoever. A waiter could specify which ring's events it is > interested > in. A 'ring' could be a single-entry thing as well, for a single > instance of pending IO.
I like this, too. (Not surprisingly, having outlined something like it in a mail in one of the previous threads :)).
I'll bring up the POSIX AIO "list" IO case. It wants to issue a group of IOs and sleep until they all return. Being able to cheaply instantiate a ring implicitly with the submission of the IO calls in the list will make implementing this almost too easy. It'd obviously just wait for that list's ring to drain.
I hope. There might be complications around the edges (waiting for multiple list IOs to drain?), but it seems like this would be on the right track.
I might be alone in caring about having a less ridiculous POSIX AIO interface in glibc, though, I'll admit. It seems like it'd be a pretty sad missed opportunity if we rolled a fantastic general AIO interface and left glibc to still screw around with it's own manual threading :/.
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