swap performance under 6.1

[Scott Long]

Garance A Drosihn wrote:
> At 12:03 AM -0400 4/12/06, Kris Kennaway wrote:
> 
>> On Tue, Apr 11, 2006 at 10:43:32PM +0000, David E. Cross wrote:
>>
>>>  I saw under http://www.freebsd.org/releases/6.1R/todo.html  that swap
>>>  performance under 6.x is slower then 4.X, and this is listed as "not
>>>  done".
>>>
>>  > I noticed that 6.1 seemed to be a dog, but 6.0 I thought
>>  > was better.  As a test I installed 6.0 and 6.1 in parallel
>>  > on my laptop with identical ports trees (and packages)
> 
> 
> Note...
> 
>>  > and 6.0 does feel a lot more responisve to swapping; I would
>>  > be eager to help track this down if someone could give me
>>  > some pointers.  If I have to _guess_ as to a problem it would
>>  > seem like some of the scheduling priorities changed.
>>
>> I didn't think this was a 6.1 regression compared to 6.0,
>> but 6.x compared to 4.x.  It would be good to try and
>> quantify any performance differences here - so far it's
>> just a bunch of people's subjective opinions (including
>> mine) after upgrading from 4.x.
> 
> 
> In Dave's case, the tests are explicitly 6.0-release vs
> 6.1- at april-5th.  Those are the two installations he has on
> his laptop, which he is comparing to each other via dual-
> booting.  The thing is, he's not sure how to get the numbers
> to back up the performance "feel" that he's experiencing.
> 

Is he using the same swap partitions for both of the dual-booted
OS's?  If not, he's measuring the speed of the disk at the outter
tracks vs the inner tracks.  There may indeed be performance issues
in the OS, but they need to be quanitfied in a controlled environment
and not be subject to things like this.

Scott