Concluding the SMPng project
jhb at freebsd.org
Tue Jun 13 13:34:38 UTC 2006
On Monday 12 June 2006 17:12, Chris H. wrote:
> Quoting Kris Kennaway <kris at obsecurity.org>:
> > 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 <jhb at FreeBSD.org> <>< http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve" = http://www.FreeBSD.org
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