OT: dual-core or 64 bit?

[Rick Stevens]

On Tue, 2007-01-30 at 23:03 +0000, David Fletcher wrote:
> On Sunday 28 January 2007 22:07, Jonathan Berry wrote:
> > On 1/28/07, Mick Mearns <off_by_1 at yahoo.com> wrote:
> > > Hi list;
> > >  this is off topic.
> > >
> > > I was wondering which is better a dual-core x86 cpu or an x64 cpu?
> > > Which is actually faster/better in "normal" use?
> > > How about installation problems and hardware cost?
> > >
> > > I am not planning any upgrades just yet but am curios.
> >
> > Why not get a dual-core x86_64 CPU?  All the AMD dual-core chips are
> > 64-bit and Intel's Core 2 Duo is 64-bit.  Personally, I like AMD
> > better.  There is really no reason to get a 32-bit only CPU anymore.
> > If you don't want to run 64-bit yet, you can still run 32-bit just
> > fine.  And a 64-bit installation gives you the choice to run both.
> >
> > Jonathan
> 
> If the List doesn't mind me staying off topic (it's closer to topic than 
> servicing a Chevy pickup gearbox I think ;-) ):- Next time I build a new 
> computer I'd like to be sure that I can run a Xen kernel with full 
> virtualisation. Then when I occasionally need to poke a little finger into 
> the Dark Side I can do so without having to shut down and reboot, and keep 
> the damned thing backed up so I don't ever need to do a fresh install again.
> 
> As I Understand It, if I go for an AMD chip I need to be sure to buy one that 
> incorporates technology called Pacifica. Only thing that's troubling me about 
> this is, I can't find any mention of Pacifica in connection with AMD chips in 
> the component shops.
> 
> Also, I believe I can't do it on this P4 computer because it can only do what 
> is called paravirtualisation, requiring hooks to be added to the guest OS. 
> Which is probably why I could run the 98SE installation CD OK when I played 
> with it but it wouldn't boot.
> 
> So, List, is the little bit I think I know about virtualisation correct?
> 
> Are there chips available now that have Pacifica (such as the AMD Opterons) or 
> are they not out yet?

Yes, they're out.  The "official" name for Pacifica is "AMD-V".  The
Athlon64/X2 series has AMD-V, as does the Opteron 1xxx,2xxx and 4xxx
series (e.g. Opteron 1210).

If you "cat /proc/cpuinfo", look at the flags string.  AMD chips with
AMD-V will have the "svm" flag.  Intel chips will have the "vmx" flag.

I have an AMD Athlon64/X2 and an Opteron 1210.  Here's the procinfo
for each.  First, the Athlon64/X2:

[root at labrat1 ~]# cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 75
model name      : AMD Athlon(tm) 64 X2 Dual Core Processor 4600+
stepping        : 2
cpu MHz         : 2405.042
cache size      : 512 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm
3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips        : 6014.10
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

And now the Opteron 1210:

[root at bigdog ~]# cat /proc/cpuinfo
processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : Dual-Core AMD Opteron(tm) Processor 1210
stepping        : 2
cpu MHz         : 1808.283
cache size      : 1024 KB
physical id     : 0
siblings        : 1
core id         : 0
cpu cores       : 1
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu tsc msr pae mce cx8 apic mtrr mca cmov pat pse36
clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm
3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm cr8_legacy
bogomips        : 4521.67
TLB size        : 1024 4K pages
clflush size    : 64
cache_alignment : 64
address sizes   : 40 bits physical, 48 bits virtual
power management: ts fid vid ttp tm stc

Note the "svm" flags on both machines.  Both chips are AM2 sockets and
they're both dual-core.
----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-            The gene pool could use a little chlorine.              -
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