Subject: Re: i/o scheduling (was Re: NEW_BUFQ_STRATEGY)
To: None <email@example.com, firstname.lastname@example.org>
From: Thor Lancelot Simon <email@example.com>
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 firstname.lastname@example.org
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