New != Faster
Kris Kennaway
kris at obsecurity.org
Mon Jun 4 22:30:22 UTC 2007
On Mon, Jun 04, 2007 at 08:54:50PM +0100, Chris wrote:
> On 04/06/07, Colin Percival <cperciva at freebsd.org> wrote:
> >Tim Daneliuk wrote:
> >> Old 2 PIII @600Mhz 768K 26M/sec 4.11-stable/SMP
> >> 50-60 min
> >> New Pent D (2 core)@3.2GHz 2G 50M/sec 6.2-stable/SMP
> >> 40-50 min
> >> Fast 2 Xeon @3GHz 3G 130M/sec 4.11-stable/SMP
> >> 8 min
> >>
> >> Is the difference in speed
> >> attributable to 4.11 being faster than 6.2?
> >
> >Close. The difference in speed is due to the compiler in 4.11 being
> >faster than the compiler in 6.2. FreeBSD uses the gcc compiler, and
> >between FreeBSD 4.11 and FreeBSD 6.2 that has been upgraded from 2.9
> >to 3.4. The general trend each time gcc is upgraded is that it takes
> >2x longer to compile code, but produces code which is 5% faster (as a
> >result of "working harder" to find optimizations).
> >
> >FreeBSD 6.2 is faster than FreeBSD 4.11 for almost everything except
> >compiling itself. :-)
> >
> >Colin Percival
> >
> >_______________________________________________
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> >
>
> What about all the following observations?
>
> slower disk performance especially under QUOTA.
s/especially//, unless you have further evidence I don't know about.
> both of these have been confirmed numerous times by different people
> so sweeping them under the carpet and saying they simply not true
> would be wrong.
My detailed measurements of disk performance and those of others I am
aware of contradicts your claim: 6.x equals or outperforms 4.x on disk
I/O (depends on driver) and filesystem I/O. The only true part of it
is the "under QUOTA" part, which as you know from past discussions, is
still under Giant in 6.x. As you also know, there is a patch to
address this which is awaiting user testing. Have you tested it yet?
Kris
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