Re: [Patch] vectored aio: IO_CMD_P{READ,WRITE}V and fops->aio_{read,write}v

[Zach Brown <zach.brown@oracle.com>]

Christoph Hellwig wrote:
> On Fri, Nov 04, 2005 at 05:03:58PM -0800, Zach Brown wrote:

>> If we're going down this path, and find ourselves touching every vectored
>> implementation in the world, I wonder if we shouldn't consider that iovec
>> container.  The desire is to avoid the duplicated iovec walking that happens at
>> the various layers by storing the result of a single walk.  An ext3 O_DIRECT
>> write walks the iovec no fewer than 7 times:

> As we discussed a while ago adding some kinds of fs_iovec or kern_iovec
> structure that records useful addition information could help this.
> Would you mind prototyping it?

Yeah, I have a patch that I've been kicking around.  It's working out
pretty well, though there are some kinks to work around.  Nothing fatal
so far.  I realized when I finally sat down to it that we can just or
together the ptr/len bits and cache them in the structure to help lower
layers with the alignment checks they're currently doing.

> The nice part about the consolidation work I'm doing now is that we'd
> need to touch much fewer places for this than before.

Cool.

I'll try and send something out the next few days.

- z