Re: [PATCH 1/2] aio: add vectored I/O support

[William Lee Irwin III]

On Sat, Oct 16, 2004 at 07:18:45AM +0200, Avi Kivity wrote:
>> It is a huge performance win, at least on the 2.4-based RHEL kernel. 
>> Large reads (~256K) using 4K iocbs are very slow on a large RAID, while 
>> after I coded a similar patch I got a substantial speedup.

On Sat, Oct 16, 2004 at 06:37:21AM +0100, Joel Becker wrote:
> 	I'd think we should fix the submission path instead.  Why create
> iovs _and_ iocbs when we only need to create one?  And even if we
> decided aio_readv() was still nice to keep, we'd want to fix this
> inefficiency in io_submit().

Disk I/O can vector across iocb's; however, network I/O requires
temporal ordering not imposed by sequential iocb submission, barring
unusual extensions to the semantics.


-- wli
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