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

[User Ota]

On Sat, Dec 22, 2007 at 09:08:02AM +0100, Claus Guttesen wrote:
> > I will need to build several Web caches over the next few months,
> > and just took advantage of the Christmas lull (and a snowy day,
> > when I couldn't work outside) to test FreeBSD 7.0 BETA 4 to see how
> > it will perform at this task. I built up a 4 core FreeBSD box, and
> > asked a friend who's a Linux fanatic to do the same with Linux on
> > identical hardware. I didn't watch closely how he installed
> > everything, but asked him not to tune  it beyond setting it up
> > properly for SMP.
> >
> > We then ran a test suite in which a client starts several
> > processes. Each uses wget to fetch a series of objects in rapid
> > succession via the cache. The fetches done by each process are the
> > same batch of URLS, but shuffled differently, so each URL will get
> > a miss the first time and then hits each time it comes up
> > thereafter unless the cache overflows. We're doing all GETs, with
> > no tricky stuff like subranges.
> >
> > As has been reported in some other messages on this list, Linux is
> > currently blowing FreeBSD away. It's taking as much as 20% less
> > time to get through the benchmark, depending on exactly how the
> > random shuffle came out. This is with 4 GB RAM, the GENERIC FreeBSD
> > SMP kernel (using SCHED_ULE), and aufs as the storage schema for Squid.
> >
> > 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.
> 
> -- 
> regards
> Claus
> 
> When lenity and cruelty play for a kingdom,
> the gentlest gamester is the soonest winner.
> 
> Shakespeare
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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.


Russell Doucette