Re: [dm-devel] [PATCH 4/5] aio: vmap ringbuffer

[Zach Brown <zab redhat com>]

> If it is measurable I'll take another stab at using memory from
> __get_free_pages() for the ringbuffer. That really would be the ideal
> solution.

No, then you'll run into high order allocation failures with rings that
don't fit in a single page.

> The other reason I wanted to do this was for the aio attributes stuff -
> for return values, I think the only sane way is for the return values to
> go in the ringbuffer, which means records are no longer fixed size so
> dealing with pages is even more of a pain.

Then let's see that, please.

And can we please stop calling them attributes?  They're inputs and
outputs that change behaviour -- they're interfaces.

And no, just for the record, I don't think generic packed variable size
structs are worth the trouble.

If we're going to do a generic interface extension mechanism then we
should put it in its own well thought out system calls, not staple it on
to the side of aio because it's there.  It's a really crummy base to
work from.

- z