swap performance under 6.1

[David E. Cross]

Yes, I wouldn't be at all surprised to find out that my 6.1 partition
has a bad block in .. say.. libc that's delaying reads and causing me
trouble, I just remember installing 6.1 and thinking "OUCH".

I get the impression that this is a latency issue more then a bandwidth
issue (responsiveness vs performance).  so I think that any long running
test to see how effecitvely we swap isn't going to show anything.

I could totally re-partition and get 4.x, 5.x and 6.x all on
concurrently if that would help.  But I think I would need a good test
program to have waiting in the wings to quantitatively measure the
differences; anyone have any ideas?

(and yes, as Garance quoted, swap partition is shared)

-- 
David E. Cross

On Wed, 2006-04-12 at 14:46 -0400, Garance A Drosihn wrote:
> At 11:44 AM -0600 4/12/06, Scott Long wrote:
> >Garance A Drosihn wrote:
> >>At 12:03 AM -0400 4/12/06, Kris Kennaway wrote:
> >>>
> >>>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 outer
> >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.
> 
> David has been talking about this on a local chat system for a
> week or two now, but apparently he doesn't track the freebsd
> mailing lists as much as I do...
> 
>  From a comment he made on that chat system:
> 
>    - As an additional datapoint, I am actually sharing the
>    - swap partition between the 6.0 and 6.1 partitions, so
>    - that should eliminate any problems there.  Now is the
>    - 6.1 partition itself has disk issues it could still
>    - explain my problems
> 
>    - OS's are on the same physical drive, different partition,
>    - GENERIC for 6.0 and 6.1
> 
> It wouldn't surprise either me or David if this was something
> specific to his system or his setup, but we're running out of
> ideas of what that would be.  (and we're both busy juggling a
> few other things in our main jobs, so we're probably not as
> focused on this as issue we would like to be...).
>