Multi-core CPU and powersaving

david wrote:


>
>> If I get a multicore cpu, AMD or Intel, with a linux kernel will it turn
>> off or make cores idle when the system does not need them?
>
> Yes.

Excellent, so whilst the pc, methphorically, might glow cherry red whilst
doing something intensive it might even run cooler than its current 2.5GHz
Athlon when lightly loaded?

Pete


--
http://www.petezilla.co.uk

On 7/12/2009 4:49 PM, Peter Chant wrote:
> david wrote:
>
>>> If I get a multicore cpu, AMD or Intel, with a linux kernel will it turn
>>> off or make cores idle when the system does not need them?
>> Yes.
>
> Excellent, so whilst the pc, methphorically, might glow cherry red whilst
> doing something intensive it might even run cooler than its current 2.5GHz
> Athlon when lightly loaded?

You might need some additional packages from a repository; depends on the
distro.

Google "linux cpu speed toggling" for more info.

Since you mentioned a 2.5GHz Athlon, my Fedora system is running with an
AMD Athlon X2 4850e. When busy, it's operating at 2.5GHz, and when idle it's
at 1GHz per the top panel's CPU Frequency Scaling Monitor (added to the panel
by right-clicking on the panel and choosing the Monitor). The Monitor can
also be used to set a fixed speed; for the 4850e the speed choices are 1, 1.8,
2, 2.2, 2.4, and 2.5GHz.

Just sitting at a terminal window:

$ cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 15
model : 107
model name : AMD Athlon(tm) Dual Core Processor 4850e
stepping : 2
cpu MHz : 1000.000
cache size : 512 KB
physical id : 0
siblings : 2
core id : 0
cpu cores : 2
apicid : 0
initial apicid : 0
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge 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 extapic cr8_legacy 3dnowprefetch
bogomips : 2009.07
clflush size : 64
power management: ts fid vid ttp tm stc 100mhzsteps

processor : 1
[...]

Thad Floryan wrote:

> You might need some additional packages from a repository; depends on the
> distro.
>

Slackware. If its not in there its probally not that difficult to add.

> Google "linux cpu speed toggling" for more info.

What a cheat, when I googled "linux cpu speed toggling" the third entry was
your very post suggesting I google. No more rentrant google searches
please...

Hmm, powernowd looks interesting, but maintainer has dropped it in favour of
the kernel governor. I ought to read up on that.

>
> Since you mentioned a 2.5GHz Athlon, my Fedora system is running with an
> AMD Athlon X2 4850e. When busy, it's operating at 2.5GHz, and when idle
> it's at 1GHz per the top panel's CPU Frequency Scaling Monitor (added to
> the panel
> by right-clicking on the panel and choosing the Monitor). The Monitor can
> also be used to set a fixed speed; for the 4850e the speed choices are 1,
> 1.8, 2, 2.2, 2.4, and 2.5GHz.

Just contemplating whether to upgrade now. Up till about six months back
all was well. Have upgraded to 1GB ram but more and more I find the
machine is not as responsive as I would like. Its less responsive on
occasion than my 900MHz Celeron M powered eee. However, the eee does not
have to many daemons and otherthings running away quietly in the backgroud
where as this pc does. And all the stuff quietly running in the background
here is doing useful stuff.

I've found I can get a newer triple core with 6MB L3 for the same price as
an older quad core AND motherboard. Rather thinking that perhaps the more
cache on the dearer processor _might_ be better than the extra core. Plus
it is 95W versus 125W (I think). Plus someone indicated that on mobo they
managed to unlock the unused core!

Since I'm not a gamer, so I don't care about the latest and greatest
graphics cards and I don't intend to overclock I'm thinking that this x3
processor in a relatively inexpensive mobo would be a good combination.


That and it would be nice to virtualise at near native speed which everyone
bar me seems able to do.



>
> Just sitting at a terminal window:
>
> $ cat /proc/cpuinfo
> processor : 0
> vendor_id : AuthenticAMD
> cpu family : 15
> model : 107
> model name : AMD Athlon(tm) Dual Core Processor 4850e
> stepping : 2
> cpu MHz : 1000.000
> cache size : 512 KB
> physical id : 0
> siblings : 2
> core id : 0
> cpu cores : 2
> apicid : 0
> initial apicid : 0
> fdiv_bug : no
> hlt_bug : no
> f00f_bug : no
> coma_bug : no
> fpu : yes
> fpu_exception : yes
> cpuid level : 1
> wp : yes
> flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge 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 extapic cr8_legacy 3dnowprefetch
> bogomips : 2009.07
> clflush size : 64
> power management: ts fid vid ttp tm stc 100mhzsteps
>
> processor : 1
> [...]

Well, if comparing notes when I said athlon I meant ye old Athlon XP, 32
bit, single core. Confused, if counting bogomips my vetrnerable CPU pounds
yours into a pulp!

cat /proc/cpuinfo
processor : 0
vendor_id : AuthenticAMD
cpu family : 6
model : 10
model name : AMD Athlon(tm) XP 2500+
stepping : 0
cpu MHz : 1825.982
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 1
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca
cmov pat pse36 mmx fxsr sse syscall mmxext 3dnowext 3dnow up
bogomips : 3651.96
clflush size : 32
power management: ts


--
http://www.petezilla.co.uk

On 7/13/2009 12:35 PM, Peter Chant wrote:
> Thad Floryan wrote:
> < [...]
>
> Just contemplating whether to upgrade now. Up till about six months back
> all was well. Have upgraded to 1GB ram but more and more I find the
> machine is not as responsive as I would like.

Additional memory is generally the "best" upgrade, followed by a CPU upgrade.

> [...]
> I've found I can get a newer triple core with 6MB L3 for the same price as
> an older quad core AND motherboard. Rather thinking that perhaps the more
> cache on the dearer processor _might_ be better than the extra core.

6MB cache makes a noticeable difference (e.g., "feel").

> Plus it is 95W versus 125W (I think).

That's a lot. I upgraded my Athlon X2 4200 (65W) to the 4850e (45W) for
the lower power and higher clock speed. The 4850e was US$54 at Newegg back in
March 2009.

> [...]
> That and it would be nice to virtualise at near native speed which everyone
> bar me seems able to do.

Not all chips have hardware-assisted virtualization. I had to upgrade another
system's CPU from an Intel Dual-Core E2220 to an Intel Core 2 Duo E8500 (both
at 65W) specifically for the virtualization hardware support. Adding 2GB RAM,
for a total of 4GB, was a simultaneous upgrade to assist virtualization.

If virtualization (hardware-assisted) is what you want, spend some time on
both Intel's and AMD's web sites to check the specs, then price-shop at online
stores such as Newegg and Fry's -- price competition and daily/weekly specials
between those two can result in substantial savings.

>> [...]
>> Just sitting at a terminal window:
>>
>> $ cat /proc/cpuinfo
>> processor : 0
>> vendor_id : AuthenticAMD
>> cpu family : 15
>> model : 107
>> model name : AMD Athlon(tm) Dual Core Processor 4850e
>> [...]
>> cpu MHz : 1000.000
>> [...]
>> bogomips : 2009.07
>> [...]
>
> Well, if comparing notes when I said athlon I meant ye old Athlon XP, 32
> bit, single core. Confused, if counting bogomips my vetrnerable CPU pounds
> yours into a pulp!
>
> cat /proc/cpuinfo
> processor : 0
> vendor_id : AuthenticAMD
> cpu family : 6
> model : 10
> model name : AMD Athlon(tm) XP 2500+
> [...]
> cpu MHz : 1825.982
> [...]
> bogomips : 3651.96

Heh! I don't know at which point and under which conditions bogomips is
computed. Note my 4850e is at 1GHz (not 2.5GHz) in the above.

I have an old Pentium-S system, 100MHz, 64MB RAM, running Red Had 5.2 (1998),
with kernel 2.0.36. I just booted it up and got 40.04 bogomips. Yes, that's
forty. Runs sendmail, gcc, emacs, etc. just fine; no X running.

The interesting (to me) thing is, that old system compiles/links a major
program I wrote in the 1990s in 12 minutes at the same time a DEC-2020 running
TOPS-20 required 35 minutes to perform the same compile/link.

On 7/13/2009 5:49 PM, Thad Floryan wrote:
> On 7/13/2009 12:35 PM, Peter Chant wrote:
>> Thad Floryan wrote:
>>> [...]
>>> Just sitting at a terminal window:
>>>
>>> $ cat /proc/cpuinfo
>>> processor : 0
>>> vendor_id : AuthenticAMD
>>> cpu family : 15
>>> model : 107
>>> model name : AMD Athlon(tm) Dual Core Processor 4850e
>>> [...]
>>> cpu MHz : 1000.000
>>> [...]
>>> bogomips : 2009.07
>>> [...]
>> Well, if comparing notes when I said athlon I meant ye old Athlon XP, 32
>> bit, single core. Confused, if counting bogomips my vetrnerable CPU pounds
>> yours into a pulp!
>>
>> cat /proc/cpuinfo
>> processor : 0
>> vendor_id : AuthenticAMD
>> cpu family : 6
>> model : 10
>> model name : AMD Athlon(tm) XP 2500+
>> [...]
>> cpu MHz : 1825.982
>> [...]
>> bogomips : 3651.96
>
> Heh! I don't know at which point and under which conditions bogomips is
> computed. Note my 4850e is at 1GHz (not 2.5GHz) in the above.
> [...]

Out of curiosity, I set the "cpu MHz" to 2500.000 via the CPU Frequency Scaling
Monitor, and the bogomips now displays as 5022.70 for each core, so that shows
a "cat /proc/cpuinfo" recalculates bogomips on demand. I receive the following
for each core at all settable frequencies:

1.0, 2009.08 bogomips
1.8, 3616.34
2.0, 4081.16
2.2, 4419.97
2.4, 4821.79
2.5, 5022.70

Interestingly, at 1.8GHz the 4850e's per core bogomips is very close to your
2500+ at 1.825GHz.

Learn something new every day.

On Sun, 12 Jul 2009 19:05:50 +0100, Peter Chant wrote:

> If I get a multicore cpu, AMD or Intel, with a linux kernel will it turn
> off or make cores idle when the system does not need them? I'm
> primarily thinking that this would keep the system cool but would not
> complain about saving power.

I think that all comes under the ACPI configuration.
grep dmesg to see what is happening.



--

Great advances in Debian Linux; post a bug report and get spam in three
days.

terryc wrote:

> On Sun, 12 Jul 2009 19:05:50 +0100, Peter Chant wrote:
>
>> If I get a multicore cpu, AMD or Intel, with a linux kernel will it turn
>> off or make cores idle when the system does not need them? I'm
>> primarily thinking that this would keep the system cool but would not
>> complain about saving power.
>
> I think that all comes under the ACPI configuration.
> grep dmesg to see what is happening.
>
Haven't bought one yet!

Pete
--
http://www.petezilla.co.uk

Thad Floryan wrote:


> Additional memory is generally the "best" upgrade, followed by a CPU
> upgrade.

Yes. But machine takes DDR, not DDR2. Guess which is cheaper. This box
has got to the point where upgrades get expensive for what you get.

However, though not perhaps the ideal combo I can re-use the system to make
a PVR. Not as good as buying a mobo more suitable for the job, but not a
loss.

>
>> Plus it is 95W versus 125W (I think).
>
> That's a lot. I upgraded my Athlon X2 4200 (65W) to the 4850e (45W)
> for the lower power and higher clock speed. The 4850e was US$54 at Newegg
> back in March 2009.
>

Exactly. I'd really like to have something that consumes less power and
makes less heat. But I also need more power than my current set up. OTOH
perhaps my current system is so old anything is a major set up.

Perhaps I ought to re-evaluate what I need. In the past I've always tried
to go for the sweet spot, a some way behind bleeding edge where the prices
are reasonable but you are not buying kit that it almost obsolete.

I suppose the thoughts are, I could spend £250* on upgrading every 4-5 years
or sit a bit further behind the leading edge and go for £100 upgrade every
two years.

*I can go quad or triple core for less than that.

>> [...]
>> That and it would be nice to virtualise at near native speed which
>> everyone bar me seems able to do.
>
> Not all chips have hardware-assisted virtualization. I had to upgrade
> another system's CPU from an Intel Dual-Core E2220 to an Intel Core 2 Duo
> E8500 (both at 65W) specifically for the virtualization hardware support.
> Adding 2GB RAM, for a total of 4GB, was a simultaneous upgrade to assist
> virtualization.
>
> If virtualization (hardware-assisted) is what you want, spend some time on
> both Intel's and AMD's web sites to check the specs, then price-shop at
> online stores such as Newegg and Fry's -- price competition and
> daily/weekly specials between those two can result in substantial savings.
>

Not in the US, but I have noted considerable sayings on motherboard/CPU
bundles. You must not be too choosy for which parts you want.
Unfortunatly the pounds recent crash has not helped the IT industys $1 = £1
calculation.

Pete


--
http://www.petezilla.co.uk

On Tue, 14 Jul 2009 08:22:40 +0100, Peter Chant wrote:


>> I think that all comes under the ACPI configuration. grep dmesg to see
>> what is happening.
>>
> Haven't bought one yet!

Search-engine linux acpi doco


--

Great advances in Debian Linux; post a bug report and get spam in three
days.

Thad Floryan wrote:

> On 7/13/2009 12:35 PM, Peter Chant wrote:
>> Thad Floryan wrote:
>> < [...]
>>
>> Just contemplating whether to upgrade now. Up till about six months back
>> all was well. Have upgraded to 1GB ram but more and more I find the
>> machine is not as responsive as I would like.
>
> Additional memory is generally the "best" upgrade, followed by a CPU
> upgrade.
>
>> [...]
>> I've found I can get a newer triple core with 6MB L3 for the same price
>> as
>> an older quad core AND motherboard. Rather thinking that perhaps the
>> more cache on the dearer processor _might_ be better than the extra core.
>
> 6MB cache makes a noticeable difference (e.g., "feel").
>
>> Plus it is 95W versus 125W (I think).
>
> That's a lot. I upgraded my Athlon X2 4200 (65W) to the 4850e (45W)
> for the lower power and higher clock speed. The 4850e was US$54 at Newegg
> back in March 2009.


Ah ha, the 705E, a triple core Phenom that consumes 65W. £93:90 inc vat
http://www.ebuyer.com/product/167111
Even has 6MB L3 cache.

Just trying to find your processor for price / performance comparison with
old processor as much as the one abov.

Hmm, the 4850e, best price £44:
http://computing.kelkoo.co.uk/c-110901-cpus.html?keyword1=4850e

OK, looking at http://www.cpubenchmark.net/cpu_list.php, the 4850e should be
about three times faster than the existing Athlon XP 2500+. Assuming that
the benchmark is a reliable indicator for my use...

OK, no direct benchmark for the Phenom, perhaps not quite twice as fast as
the 4850e. Interesting comment:

"The same CPU as before. Higher binning an lower voltage thats all.

You're better of saving money and buy a Phenom II x3 710/720BE and undervolt
it yourself."

Ref: http://www.xtremesystems.org/Forums/showthread.php?t=227477

I've found the 710 and 720 from the same supplier for £92 and £107
respectively. Well, not tried underclocking, but would underclocking from
2.6 to 2.5GHz and reducing the voltage really make that much difference?
If it does no reason not to get the 710.

So, just have to make my mind up. 4850e like you or 710. AM3 mobos are not
cheap, nor is DDR3 memory. AM2+ motherboards seem to start around the £50
mark and take cheaper DDR2 memory. Hmm, looks around £125 versus £175.
Hmm.

Thanks for your help.

Pete

--
http://www.petezilla.co.uk

david wrote:
> On Sun, 12 Jul 2009 19:05:50 +0100, Peter Chant rearranged some electrons
> to say:
>
>> If I get a multicore cpu, AMD or Intel, with a linux kernel will it turn
>> off or make cores idle when the system does not need them?
>
> Yes.
>

And not only that, but can run the cores at different frequencies as well. Just to make things really complicated.