Subject: Re: i/o scheduling (was Re: NEW_BUFQ_STRATEGY)
To: None <,>
From: Thor Lancelot Simon <>
List: tech-kern
Date: 12/17/2003 01:33:53
On Wed, Dec 17, 2003 at 03:30:15PM +0900, YAMAMOTO Takashi wrote:
> > 
> > Why would these reads be generated?  If the write has not completed, is
> > it not the case that the page must still be dirty, and should thus still
> > be in the cache?
> because the page is marked as PG_BUSY during delayed write,
> VOP_GETPAGES will wait on it.  we have no way to hurry
> the i/o in this case.
> maybe distinguishing PG_BUSY-for-read and PG_BUSY-for-write can be
> an alternative solution?

Won't this also help avoid reads, period, when the I/O queues get lots
of writes backed up in them?  That seems like a very good thing.

 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