Re: O->A loan

[yamt%mwd.biglobe.ne.jp@localhost (YAMAMOTO Takashi)]

hi,

> 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 it's quite a bit out of date, but I think most of the changes needed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

thanks.  it seems that i've read the thread. :-)

what is the "pt" command used in the benchmark?
does it break loans?

YAMAMOTO Takashi

> 
> -Chuck