Subject: Re: UBC performance patch
To: None <eeh@netbsd.org, chuq@chuq.com, tech-kern@netbsd.org>
From: Jason R Thorpe <thorpej@zembu.com>
List: tech-kern
Date: 01/26/2001 09:17:12
On Fri, Jan 26, 2001 at 09:10:46AM -0800, Jason R Thorpe wrote:

 > Perhaps we want a new "ubc_inactive" list, which isn't counted in the
 > inactive target?  And always include ubc_inactive in the inactive scan
 > (as opposed to including it in the object vs. swap backed toggle).

Actually, another thing that needs to happen is dealing with the
write backlog.  Right now, pages aren't getting cleaned fast enough
when I/O write load is high.

What the old buffer cache would have done is force a process to block
waiting for a buffer if there weren't any left to give it -- while it
cleaned a buffer to give the requester.

One option might be to have a dirtyvnode threshold that causes writes
to block until the dirtyvnode count drops below the threshold, and
kick the pagedaemon to clean the pages.

-- 
        -- Jason R. Thorpe <thorpej@zembu.com>