Subject: Re: i/o scheduling (was Re: NEW_BUFQ_STRATEGY)
To: None <firstname.lastname@example.org>
From: YAMAMOTO Takashi <email@example.com>
Date: 12/17/2003 15:46:35
> > > 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.
anyway, it won't help other cases like fsync on the
delayed writed pages, etc.