Re: O->A loan

[Chuck Silvers <chuq%chuq.com@localhost>]

On Mon, Nov 28, 2011 at 03:45:53AM +0000, YAMAMOTO Takashi wrote:
> hi,
> 
> > On Sun, Nov 20, 2011 at 06:52:10PM +0000, YAMAMOTO Takashi wrote:
> >> hi,
> >> 
> >> i'd like to to either fix or remove O->A page loaning.
> >> 
> >> the biggest problem is the lack of users.  thus no way to test.
> >> any ideas?
> > 
> > some years ago I wrote some prototype code to use the O->A loaning for
> > read() and write().  the read() side worked, I don't think I had tested
> > the write() side so it probably has problems.  the patch is still around:
> > ftp://ftp.netbsd.org/pub/NetBSD/misc/chs/diff.uvm_readloan.8
> > 
> > it's quite a bit out of date, but I think most of the changes needed
> > to update it would be mechanical.
> 
> i'll take a look.  thanks.
> 
> did it (at least the read() side) have actual performance benefit
> compared to dumb copying?

it helped quite a lot, yes.  here's the email thread:
http://mail-index.netbsd.org/tech-kern/2005/02/15/0021.html

-Chuck