RE: VCool - cool your Athlon/Duron during idle

RE: VCool - cool your Athlon/Duron during idle

[Grover, Andrew]

Well I don't want to inhibit your hackerly fervor, but C2 and C3 handling
are already supported by the ACPI driver, in a vendor-neutral manner.

If you take a look at the code, you will notice a few things. First, it only
transitions to a deeper sleep state after doing some number of lighter
sleeps. This is to minimize the performance hit caused by C2/C3 entry and
exit latencies. Second, it only uses a given processor power state if the
system's ACPI tables indicates they can be used. If you are attempting to
use C2 even if your system explicitly does not support it, you are asking
for trouble, just like AMD's errata says.

Besides I'd think any cooling issues would occur when the CPU was 100%
utilized, yes? Why are you trying to optimize the idle loop for power when
it's not the problem? You can throttle the processor or turn a fan on to
handle a too-hot cpu, but all C2/C3 gets you is reduced power when idle.
This results in better battery life on a laptop but that is irrelevant on a
desktop system.

Regards -- Andy

> -----Original Message-----
> From: Jan Niehusmann [mailto:jan@gondor.com]
> Sent: Sunday, August 26, 2001 4:01 PM
> To: Dieter Nützel
> Cc: Alan Cox; Linux Kernel List
> Subject: Re: VCool - cool your Athlon/Duron during idle
> Importance: High
> 
> 
> On Sun, Aug 26, 2001 at 08:09:34PM +0200, Dieter Nützel wrote:
> > Have you read something about this Athlon/Duron cooling problem?
> > Can this code included into your (and/or the official) tree?
> 
> I haven't yet measured if this really saves a significant amount of
> power, but I made a kernel patch closely based on the vcool patch
> from http://www.naggelgames.de/vcool/
> 
> This patch is extremely experimental, but it didn't crash my 
> machine, yet ;-) Some things could probably be more elegant.
> 
> Feel free to comment or use this patch as you like.
> It does only use stpclk if you boot with idle=stpclk
> 
> Jan

Re: VCool - cool your Athlon/Duron during idle

[Jan Niehusmann]

On Mon, Aug 27, 2001 at 02:26:09AM -0700, Grover, Andrew wrote:
> system's ACPI tables indicates they can be used. If you are attempting to
> use C2 even if your system explicitly does not support it, you are asking
> for trouble, just like AMD's errata says.

Motherboard vendors may have disabled the bus disconnection because of a
3% performance hit, to make their boards look better in benchmarks.
In that case, the system may run perfectly stable with disconnection reenabled.

I agree that these experiments should not be performed on a production
system :) 

> This results in better battery life on a laptop but that is irrelevant on a
> desktop system.

Well, I think saving ~55W is relevant, even on a desktop system. I plan
to measure how much power these hacks really save, and if it's more than
10W, I think it's worth some more work in this area.

Jan

(asus writes that one of the problems that can happen with this power
saving mode are the huge changes in power dissipation, from 60W to 5W
and back - therefore I assume the power saving mode can save up to 55W)

Slow system with K7

[Carlos Costa Portela]

	Hello all!

	I know that -perhaps- this is not a kernel-directly question, but
here it is:

	I have a K7,  1.2 GHz, 266 MHz micro with the A7M266 motherboard
and 256 Mb DD SDRAM. (I had a Pentium III, 500Mhz and just 128 mb ram).
What I see now is two things:

	1. the system is more loaded than in the pentium epoch
	2. sometimes, the system "stops" for small periods of time (< 1s).

	I am using 2.4.9 kernel. Can you give me any tip to get the most
from my system?. I'm recompiling all applications and, yes, if once
recompiled I can see that the system improves.

	Thanks in advance,
		Carlos.

  http://www.improveyourweb.com : All about web, PHP-Nuke based site
             [ Web info for and from web people: enjoy it! ]

 _______Carlos Costa Portela__________________________________________
|   e-mail:  ccosta@servidores.net  |     http://www.registros.net    |
|   www: http://ccp.servidores.net  |     http://www.avisaboe.com     |
|      http://www.biologia.org      |   http://moana.servidores.net   |
|__Tódalas persoas maiores foron nenos antes, pero poucas se lembran__|

Re: VCool - cool your Athlon/Duron during idle

[Alan Cox]

> handle a too-hot cpu, but all C2/C3 gets you is reduced power when =
> idle.
> This results in better battery life on a laptop but that is irrelevant =
> on a
> desktop system.

Thus speaks the country with chronic californian power shortages, and that
wouldn't sign up to a global accord on global warming 8)

C2 and C3 are useful IMHO even on a desktop PC. The slight hit on the
transition is not noticable, the change on the power bill is.

Alan

Re: Slow system with K7

[Alan Cox]

> 	1. the system is more loaded than in the pentium epoch
> 	2. sometimes, the system "stops" for small periods of time (< 1s).
> 	I am using 2.4.9 kernel. Can you give me any tip to get the most
         ^^^^^^^^^^^^^^^^^^^

I suspect that bit is your actual problem. 

> from my system?. I'm recompiling all applications and, yes, if once
> recompiled I can see that the system improves.

>From what I can measure Athlon specific code really only makes a difference
when using prefetches, mmx or 3dnow. For most code streams Athlon's seem
to extract good parallelism out of 586/686/k6/.. code.

Alan

Re: VCool - cool your Athlon/Duron during idle

[Liakakis Kostas]

On Mon, 27 Aug 2001, Jan Niehusmann wrote:

> Motherboard vendors may have disabled the bus disconnection because of a
> 3% performance hit, to make their boards look better in benchmarks.
> In that case, the system may run perfectly stable with disconnection reenabled.

There is still another reason..

> (asus writes that one of the problems that can happen with this power
> saving mode are the huge changes in power dissipation, from 60W to 5W
> and back - therefore I assume the power saving mode can save up to 55W)

The problem they are describing is not the change in power dissipation,
but the change in current draw from the regulated 1.75V (difference of
about 30A or more). During this almost instantaneous transition either
your mobo regulator or your PSU can give up for a while and you get a nice
crash. This tends to happen more often with the 1400-Cs.

-K.

Re: VCool - cool your Athlon/Duron during idle

[Dieter Nützel]

Am Montag, 27. August 2001 12:42 schrieb Alan Cox:
> > handle a too-hot cpu, but all C2/C3 gets you is reduced power when =
> > idle.
> > This results in better battery life on a laptop but that is irrelevant =
> > on a
> > desktop system.
>
> Thus speaks the country with chronic californian power shortages, and that
> wouldn't sign up to a global accord on global warming 8)

We are one step further, here in "old" Germany...

http://www.powerplant-for-sale.com/en/index.htm :-)))

> C2 and C3 are useful IMHO even on a desktop PC. The slight hit on the
> transition is not noticable, the change on the power bill is.

I second that.

-Dieter

Re: VCool - cool your Athlon/Duron during idle

[Kurt Roeckx]

On Mon, Aug 27, 2001 at 02:48:24PM +0300, Liakakis Kostas wrote:
> On Mon, 27 Aug 2001, Jan Niehusmann wrote:
> 
> > (asus writes that one of the problems that can happen with this power
> > saving mode are the huge changes in power dissipation, from 60W to 5W
> > and back - therefore I assume the power saving mode can save up to 55W)
> 
> The problem they are describing is not the change in power dissipation,
> but the change in current draw from the regulated 1.75V (difference of
> about 30A or more).

And what do you think power is?
Maybe it's the voltage times the current?


Kurt

Re: VCool - cool your Athlon/Duron during idle

[Liakakis Kostas]

On Mon, 27 Aug 2001, Kurt Roeckx wrote:

> On Mon, Aug 27, 2001 at 02:48:24PM +0300, Liakakis Kostas wrote:
> > On Mon, 27 Aug 2001, Jan Niehusmann wrote:
> > 
> > > (asus writes that one of the problems that can happen with this power
> > > saving mode are the huge changes in power dissipation, from 60W to 5W
> > > and back - therefore I assume the power saving mode can save up to 55W)
> > 
> > The problem they are describing is not the change in power dissipation,
> > but the change in current draw from the regulated 1.75V (difference of
> > about 30A or more).
> 
> And what do you think power is?
> Maybe it's the voltage times the current?

Your point being? This is power yeah. However I can get 50W with 1V@50A
and with 50V@1A ... tell me which will be easier for a regulator when
going from 10 to 50W while trying to keep the voltage steady.

So to rephrase myself the condition of less power dissipation (and that is
thermal output, not power consumption which isvoltage times current... )
is the result of less current draw of ~30A. This is a huge difference. And
this is the problem. There are regulators on certain motherboards which
can't cope with this. And they increase (not that bad unless you fry a 
chip) when current drops, or decrease voltage when there is current need
(crash) of the tolerance limmits.

Sorry for the OT.

-K.

Re: VCool - cool your Athlon/Duron during idle

[Paul G. Allen]

Alan Cox wrote:
> 
> > handle a too-hot cpu, but all C2/C3 gets you is reduced power when =
> > idle.
> > This results in better battery life on a laptop but that is irrelevant =
> > on a
> > desktop system.
> 
> Thus speaks the country with chronic californian power shortages, and that
> wouldn't sign up to a global accord on global warming 8)
> 

In reality, California has no power shortage. The problem is deregulation and greed together causing an artificial power shortage. Tell those of us in San Diego
that we're using too much power and there's a shortage. We started conserving a year before the "shortage" - an average of 20% in fact - and we still had
blackouts and higher rates and were told to cut back even more or pay even more. But, this thread digresses.

> C2 and C3 are useful IMHO even on a desktop PC. The slight hit on the
> transition is not noticable, the change on the power bill is.

At our rates, you're darn right it is. An average PC costs ~$.05 per hour to run in California.

PGA

-- 
Paul G. Allen
UNIX Admin II/Programmer
Akamai Technologies, Inc.
www.akamai.com
Work: (858)909-3630
Cell: (858)395-5043

Re: VCool - cool your Athlon/Duron during idle

[Paul G. Allen]

Liakakis Kostas wrote:
> 
> On Mon, 27 Aug 2001, Kurt Roeckx wrote:
> 
> > On Mon, Aug 27, 2001 at 02:48:24PM +0300, Liakakis Kostas wrote:
> > > On Mon, 27 Aug 2001, Jan Niehusmann wrote:
> > >
> > > > (asus writes that one of the problems that can happen with this power
> > > > saving mode are the huge changes in power dissipation, from 60W to 5W
> > > > and back - therefore I assume the power saving mode can save up to 55W)
> > >
> > > The problem they are describing is not the change in power dissipation,
> > > but the change in current draw from the regulated 1.75V (difference of
> > > about 30A or more).
> >
> > And what do you think power is?
> > Maybe it's the voltage times the current?
> 
> Your point being? This is power yeah. However I can get 50W with 1V@50A
> and with 50V@1A ... tell me which will be easier for a regulator when
> going from 10 to 50W while trying to keep the voltage steady.

First of all, let me say that I used to run the lab at NCR Corporation testing and qualifying power supplies, and making design recommendations/changes when
they failed, for main frame computers. 

That would depend upon the power supply, and specifically, the regulator design. Consider that the average PC user buys a cheap $30 - $50 (US Dollars) case and
P/S package. That P/S will never be able to handle this kind of transition and stay within its specified regulation. In the electronics industry, you get what
you pay for (with the exception of a couple of big names that simply sell junk 'cause they can), and there's no exception to this rule when it comes to power
supplies. I have tested PC power supplies by various mfgs. and have found that most do not hold up to the specifications printed on them, let alone to anything
a CPU/MB mfg. may require. Many operate on the fringe of their specified voltage range even under low load, send them up to maximum load and they quickly fly
south (and many never return!). In simple terms, you won't find a P/S under $100 (US) that will be worth the CPUs weight in regulation, let alone will be able
to handle such a large power transition.

> 
> So to rephrase myself the condition of less power dissipation (and that is
> thermal output, not power consumption which isvoltage times current... )
> is the result of less current draw of ~30A. This is a huge difference. And
> this is the problem. There are regulators on certain motherboards which
> can't cope with this. And they increase (not that bad unless you fry a
> chip) when current drops, or decrease voltage when there is current need
> (crash) of the tolerance limmits.

MoBo regulators aside, as stated above, most power supplies can't handle it, so there's nothing the regulator could do no matter how well designed it is. What I
said above does stand for on-board regulators as well. 

BTW, there are two basic power ratings for an electronic component - Power Dissipation (Pd) and Power Consumption (Pc). Pd is the amount of power (V*I or
Voltage times Current) that the component wastes in heat (which is generated by the friction of electrons moving through the component). Pc is the total power
required by the component for operation, and is a function of Pd plus the power actually used by the component and not wasted in heat. Pc is also V*I. Pc is
measured by connecting meters (voltage and current) to the power connections on the component while in operation. Pd can be measured by the amount of heat
coming off of it, or by various other methods. Both Pd and Pc can be decreased by turning off portions of the component, decreasing clock speed (thereby
decreasing friction), and by decreasing voltage and/or current to minimum operational levels. It can be increased by turning off the wrong portions of the
component causing others to exceed their specifications, by increasing clock speed, by increasing voltage and/or current to maximum operational levels (or
beyond - a Bad Thing :), and by decreasing voltage and/or current below operational levels. The last scenario causes the component to do all kinds of things it
wasn't meant to do, which usually causes Pd to rise dramatically and therefore Pc follows.

So, in summary, I wouldn't use power saving modes (and I don't) unless:

1. I had 100% conviction that my P/S would meet or exceed the required specifications.
2. I had 100% conviction that the MoBo would meet or exceed the required specifications.
3. I had 100% conviction that all components in the system would meet or exceed the required specifications.

More often that not, they don't, and most consumers are none the wiser. I have never used any power saving mode because in any given case the system in question
could not meet 1 - 3.

PGA

-- 
Paul G. Allen
UNIX Admin II/Programmer
Akamai Technologies, Inc.
www.akamai.com
Work: (858)909-3630
Cell: (858)395-5043

Re: VCool - cool your Athlon/Duron during idle

[Jan Niehusmann]

On Mon, Aug 27, 2001 at 02:26:09AM -0700, Grover, Andrew wrote:
> Well I don't want to inhibit your hackerly fervor, but C2 and C3 handling
> are already supported by the ACPI driver, in a vendor-neutral manner.

I did look into this, and indeed the ACPI code is doing this much better
than my patch did. 

The only thing it is missing is enabling disconnect in C2 mode. Of course,
enabling a feature that may have been disabled by the BIOS with a good reason
may be dangerous. Still, it seems to work for me ;-) and saves a lot of power.

With the ACPI code and a simple patch that enables bus disconnection, I get
the same power saving as with the lvcool userspace program, but a much better
performance for things like NFS access. (in fact, NFS access is the only
thing where I notice a significant slowdown when running lvcool)

Additionaly, this patch is much smaller than the last one. But of course,
it's only usefull if ACPI is working (which it is for me).
I added the code to quirks.c because it allowed some quick cut&paste ;-)
The code is enabled if the kernel is booted with via_disconnect=yes

To give some numbers (measured with a simple, probably not very accurate
'power monitor'):
Idle without disconnect: ~80W
Idle with disconnect: ~60W
Compiling a kernel: ~90W
(all numbers for a Duron 800, Asus A7V133, Voodoo 3, Maxtor 80GB hard disk,
256MB RAM and some PCI cards)

By the way, does anybody know why modprobe ospm_busmgr doesn't return, but
the module works if I interrupt the modprobe with CTRL-C?

Jan


diff -ur linux-2.4.9-ac5/drivers/pci/quirks.c linux-2.4.9-ac5-vcool/drivers/pci/quirks.c
--- linux-2.4.9-ac5/drivers/pci/quirks.c	Sun Sep  2 15:37:56 2001
+++ linux-2.4.9-ac5-vcool/drivers/pci/quirks.c	Sun Sep  2 23:58:12 2001
@@ -21,6 +21,8 @@
 
 #undef DEBUG
 
+int enable_via_disconnect;
+
 /* Deal with broken BIOS'es that neglect to enable passive release,
    which can cause problems in combination with the 82441FX/PPro MTRRs */
 static void __init quirk_passive_release(struct pci_dev *dev)
@@ -146,6 +148,21 @@
 	printk(KERN_INFO "Applying VIA southbridge workaround.\n");
 }
 
+static void __init quirk_viadisconnect(struct pci_dev *dev)
+{
+	u32 res32;
+
+	if(!enable_via_disconnect) return;
+
+	pci_read_config_dword(dev,0x52&0xfc,&res32);
+	if ((res32&0x00800000)==0) {
+		printk(KERN_INFO "Enabling disconnect in VIA northbridge.\n");
+		res32|=0x00800000;
+		pci_write_config_dword(dev,0x52&0xfc,res32);
+	} else
+		printk(KERN_INFO "Disconnect already anabled in VIA northbridge.\n");
+}
+
 /*
  *	VIA Apollo VP3 needs ETBF on BT848/878
  */
@@ -453,6 +470,8 @@
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_SI,	PCI_DEVICE_ID_SI_5597,		quirk_nopcipci },
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_SI,	PCI_DEVICE_ID_SI_496,		quirk_nopcipci },
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	PCI_DEVICE_ID_VIA_8363_0,	quirk_vialatency },
+	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	PCI_DEVICE_ID_VIA_8363_0,	quirk_viadisconnect },
+	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	PCI_DEVICE_ID_VIA_8371_0,	quirk_viadisconnect },
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	PCI_DEVICE_ID_VIA_8371_1,	quirk_vialatency },
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	0x3112	/* Not out yet ? */,	quirk_vialatency },
 	{ PCI_FIXUP_FINAL,	PCI_VENDOR_ID_VIA,	PCI_DEVICE_ID_VIA_82C597_0,	quirk_viaetbf },
@@ -500,3 +519,12 @@
 	pci_do_fixups(dev, pass, pcibios_fixups);
 	pci_do_fixups(dev, pass, pci_fixups);
 }
+
+static int __init via_disconnect_setup (char *str) {
+	if(!strncmp(str,"yes",3)) {
+		enable_via_disconnect=1;
+	}
+	return 1;
+}
+
+__setup("via_disconnect=", via_disconnect_setup);