Re: Concluding the SMPng project

I have a low end "server" with a 3.2ghz single core P4 but HT is
disabled by default and that seems like a waste to me.
So my two cents would love to see actual useful gains from HT
processors if requests are being made.  :)

On 6/13/06, John Baldwin <[email protected]> wrote:
> On Monday 12 June 2006 17:12, Chris H. wrote:
> > Quoting Kris Kennaway <[email protected]>:
> >
> > > Several of us have been discussing recently whether it is time to
> > > bring the SMPng project to a formal conclusion.
> > >
> > > According to the SMPng project webpage,
> > >
> > >  "The end goal of the SMPng Project is to decompose the Giant lock
> > >  into a number of smaller locks, resulting in reduced contention (and
> > >  improved SMP performance)."
> > >
> > > Thanks to the hard work of many developers over the past ~6 years, this
> > > goal is now complete.
> > >
> > > While Giant has not been completely eliminated from the kernel and
> > > several subsystems are still giant-locked (notably ipv6, tty, and CAM,
> > > although work is in progress on all of these fronts), kernel profiling
> > > traces show that for many real-world application loads the Giant lock
> > > is simply no longer a factor in the performance of the SMP kernel.
> > >
> > > See e.g.
> > >
> > >  http://www.bsdcan.org/2006/papers/FilesystemPerformance.pdf
> > >
> > > for one such measurement of the extent of Giant locking in FreeBSD
> > > 6.x; other real-world application workloads are similar.
> > >
> > > Some of the benefits of formally concluding the SMPng project are:
> > >
> > > * The focus of SMP development work has largely changed from "break up
> > > Giant everywhere" to "carefully measure the effects of the locking
> > > decisions that were made, and optimize for greater performance and
> > > scalability".  This is a major milestone and should be announced to
> > > the world, perhaps under the banner of a new "FreeBSD Scalability
> > > Project".
> > >
> > > * For example, a number of us are looking very closely at the nascent
> > > FreeBSD port to the Sun Ultrasparc T1, which provides 32 virtual CPUs
> > > (4 threads on 8 CPU cores) on a single chip.  Optimizing for the new
> > > generation of SMP hardware is going to be a major effort over the
> > > coming year.
> >
> > Ahh, so the contributions made by the PIII & PIV CPU's were merely to
> > obtain access to the Sparc systems, and the PIII & PIV will be relegated
> > to the ubiquitous I386 scrap heap, as the future and ultimate goal of
> > FreeBSD is to be Sun Microsystems. Pitty, FreeBSD has always provided
> > such wide scalability. So easy to implement on so many architectures.
> > I wish I had known it's agenda years ago. As I would not have spent
> > so many years and so many dollars building *BSD based infrastructures.
> > Perhaps I've misunderstood this announcement. But if not;
> > good riddance.
>
> Umm, no.  However, with multi-core becoming more fashionable, x86 systems
> are going to start having more and more CPUs as well, so FreeBSD needs to
> work on scaling up to more than say 4 CPUs.
>
> --
> John Baldwin <[email protected]> <>< http://www.FreeBSD.org/~jhb/
> "Power Users Use the Power to Serve" = http://www.FreeBSD.org
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