Subject: Re: Coallesce disk I/O
To: Gordon Waidhofer <>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 01/26/2004 23:35:41
On Mon, Jan 26, 2004 at 07:51:26PM -0800, Gordon Waidhofer wrote:
> Coallescing I/O isn't going to do anything about softdep
> bugs. I just wanted to start a thread since there was
> discussion about performance under heavy load.
> It's been good. Nothing urgent, though.

FWIW, I see no reason that disksort couldn't build something
like the buffer chains that BSD/OS used to use to do FFS
clustering without the awful pagemove() hack.  Several people
have proposed this, or its equivalent.  The thing is, nobody's
seemed willing to go define such an interface and whack it into
the various disk drivers; making disksort actually merge is
by far the easy part.

Generally, our I/O subsystem needs to get smarter about several
facets of request handling.  The N of us who've picked up
per-device MAXPHYS but never finished it are all on the hook for
some of that... :-)

 Thor Lancelot Simon	                            
   But as he knew no bad language, he had called him all the names of common
 objects that he could think of, and had screamed: "You lamp!  You towel!  You
 plate!" and so on.              --Sigmund Freud