SMP on FreeBSD 6.x and 7.0: Worth doing? freenx@deweyonline.com

[User Ota]

On Sat, Dec 22, 2007 at 01:40:00PM +0100, Claus Guttesen wrote:
> > > > It appears, though I'd need to instrument the code more to be sure,
> > > > that the slowdown is coming from file I/O. Could it be that there
> > > > less concurrency or more overhead in FreeBSD file operations than
> > > > there is in Linux? Even with SoftUpdates turned on, the cache
> > > > volume mounted with -noatime, and aufs (which uses kqueues -- a
> > > > FreeBSD invention -- to optimize multithreaded disk access), the
> > > > benchmark shows FreeBSD losing out. Why?
> > >
> > > I have noticed an entry in GENERIC called
> > >
> > > device cpufreq
> > >
> > > Could this have any influence on the performance (on FreeBSD)?
> > >
> > > I saw this device late in the 7.0 release-process and I since I'm
> > > accustomed to comment out any devices and options I don't need I have
> > > commented this out as well. So I haven't performed any tests with and
> > > without this device.
> > >
> >
> > Cpufreq is for CPU frequency scaling.  In the linux world, the cpufreq
> > daemon allows you to control your cpu speed and voltage using power
> > profiles and such, which makes it a definite power saving tool for
> > laptops.  The cpufreq driver is already included with the Linux kernel,
> > so I'm going to assume that they've just implemented the cpufreq driver
> > in the kernel recently :)
> >
> > If enabled, it probably would have an impact on performance, however I
> > have lost the ability to test such a function since my laptop decides
> > not to POST anymore.
> 
> Yes, I did figure out what the purpose of this device was. :-) My
> point was that this could lead to lower benchmarks on servers if
> GENERIC is used.
> 
> -- 
> regards
> Claus
> 
> When lenity and cruelty play for a kingdom,
> the gentlest gamester is the soonest winner.
> 
> Shakespeare
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Oh, yeah, I see what you mean now.  We have GENERIC and SMP kernel 
configs, with the cpufreq driver now, there should be like a LAPTOP 
kernel config file with laptop-specific options :P

Once I get my laptop working again, though, I'll try testing it out when 
7.0-RELEASE comes about.


Russell Doucette