Author Topic: Hyperthreading & SMP  (Read 1656 times)

os2monkey

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Hyperthreading & SMP
« on: 2012.04.23, 10:17:04 »
So I just upgraded my cpu to a P4 3.0ghz that supports hyper-threading.

I had activated acpi installed by default via 2.1, and then I installed the ACPI 3.19.14 version on advice previously that is was more stable, and then rebooted.
When I rebooted my computer showed 2 cpus, but it started acting really strange, with both cpus often going up to 99%, and I could not load any apps or shut down the system.

Fortunately I had a backup image of my hard drive and restored it without acpi running.
I could try to install acpi again with just the version included with ECS 2.1.
But, i'm thinking maybe I shouldn't bother since i've been told previously by you guys that it might not help performance anyways.

So I'm just wondering if you guys think I should try acpi again, or just leave it off. Is it known not to be stable with HT cpu's?

Thanks

melf

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Re: Hyperthreading & SMP
« Reply #1 on: 2012.04.23, 11:25:44 »
I have a little Acer One with hyperthreading. Works fine on two cores until I use powerman (the power reduction utility), then things freezes. Check your config.sys, if you have a line referring to powerman - REM it and try again. ACPI 3.19.14 and the ones after, I think have the power reduction built into the ACPI deamon (?) - I have also had similar problems with that. This could be disabled via a "power reduction" object (don't remember its name) in the system setup directory.

Furthermore, next time you have trouble after installing ACPI, boot to maintance desktop, (press Alt+F1 when the eCS blob is visible and choose maintance desktop) and just REM out the ACPI lines OR use your eCS CD, boot it and check "system maintance (?)" then find "text editor" in the menu and REM out ACPI lines. You save yourself from restoring the whole image.
/M
/Mikael

ivan

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Re: Hyperthreading & SMP
« Reply #2 on: 2012.04.23, 12:57:14 »
Hi David,

You should also consider using BootAble http://hrbaan.home.xs4all.nl/bootAble/ to create a bootable CD that will allow you to undertake various maintenance tasks without your main eCS running.

ivan

DougB

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Re: Hyperthreading & SMP
« Reply #3 on: 2012.04.23, 17:54:54 »
I will present a few observations:

If you use ACPI, and you have access to Software Subscription, get the latest version 3.20.01.

Then, to use power reduction (highly recommended on a portable, battery operated, system), you need to enable the Throttling in the ACPI power object, which will be in the ACPI folder. ACPI 3.19.14 did not create that program object correctly. It has the wrong path in it.

Definitely, remove the POWERMAN.EXE line, in CONFIG.SYS. That will conflict with the new ACPI.

Melf: Also remove the older CoolMan that I gave you (that was the prototype for POWERMAN, for those who don't know). The new power controls in the new ACPI work good.

Hyperthreading: If you have a single processor, with that feature, I recommend that you don't use it. The SMP overhead will never be made up. If you have a processor with two real processors, you already have that overhead (unless you only use one processor). The new ACPI specifically says to turn off that feature, but I have seen no difference between having it enabled, or not, other than eCS thinks it is a quad core, rather than a dual core (and Win7 works faster). That is on my Lenovo ThinkPad T510. I suspect that some systems may have problems with using HT, which is why they say to turn it off.

Quote
it started acting really strange, with both cpus often going up to 99%, and I could not load any apps or shut down the system.

That is more likely to be a startup conflict of some sort. I have seen many different ways that that shows up, and your description is one of them. Two things that have "fixed" that sort of thing (recently), is to add the line:

BASEDEV=BOOTDLY.SYS /D:2

immediately after the:

PSD=ACPI.PSD

line. I also "fixed" another problem (the CONFIG.SYS is held open, so it can't be edited), by installing the Desktop Management Tool (DMT).

The main "problem" seems to be that there is a short period of time, usually at about the time that the GUI is starting up (but it can be earlier, or later), where the file system is blocked. Depending on exactly what is going on at that time, almost anything can happen. The new ACPI does seem to bring out that sort of problem (as they warn you about), because it starts up quicker than the old one. One thing that can help (and I think it is essential, when you have more than about 3 things started from the startup folder), is RXAUTOSTART. That starts the contents of the startup folder, one program at a time, after waiting for the desktop to be initialized, and that definitely reduces the chances of having startup conflicts.

7cities.net/~mckinnis/rxautost/index.html

Some experimenting with timings is probably required.

FWIW, I find that the more things that get installed (adding things to CONFIG.SYS), the more stable the system gets.

You may also find that sorting your CONFIG.SYS properly will make a difference. You can use the sort that comes with eCS, or you can use my Logical Config.Sys Sort tool, which make CONFIG.SYS much easier to understand for humans (the machine doesn't care, it will sort it out itself anyway). I found that my systems were somewhat unstable after installing the new ACPI, and the cause seems to be that the installer put the ACPI lines right at the top of CONFIG.SYS. After I sorted (using LCSS, of course), all of my ACPI capable systems have been quite good.

hobbes.nmsu.edu/download/pub/os2/util/config/LCSS-0-4-4.wpi

melf

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Re: Hyperthreading & SMP
« Reply #4 on: 2012.04.23, 20:15:46 »

//-- Melf: Also remove the older CoolMan that I gave you (that was the prototype for POWERMAN, for those who don't know). The new power controls in the new ACPI work good.--//


No, I won't yet..! 3.20.01 didn't work very well on my T43. Resume, which have worked with both 3.19.14 and 3.19.15, stopped working, and futhermore powermanagment worked bad. After reboot the CPU temperature sank just very slowly and only to 72C, without me doing anything (the normal level use to be about 62C) . I've deinstalled and installed again with the same result. So I filed a bugreport and then went back to coolman, which does its job well :-) .
/Mikael

DougB

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Re: Hyperthreading & SMP
« Reply #5 on: 2012.04.24, 16:34:29 »
Quote
powermanagment worked bad.

Did you enable it using the ACPI Power Manager program? It is turned off if you don't. You will also find that a single processor needs some adjustment under the CPU tab. I am using Slow below 50% and Speed up above 75%. The default parameters are okay for a quad core system, but they are not aggressive enough for single core machines. If you insist on using CoolMan, make sure that Throttling is disabled in ACPI Power Manager, or they will fight with each other.

S/R is something that I haven't bothered with. I suppose that I should try it.

melf

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Re: Hyperthreading & SMP
« Reply #6 on: 2012.04.24, 17:03:18 »
Yes I did enable it and yes I used more aggressive values for CPU. In some way the behaviour of 3.20.01 although bad (for me) is better than the previous embedded ones that freezes my system. So now I'm awaiting better times and take it Cool...
/Mikael

DougB

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Re: Hyperthreading & SMP
« Reply #7 on: 2012.04.25, 07:16:32 »
Just to update this (the development team knows about these problems):

Suspend Resume does not work on my Lenovo ThinkPad T510 (4313-CTO). Suspend seems to work, but resume fails somehow. The screen backlight never turns on, so I can't see what is going on (if anything). Ctrl-Alt-Del does something (it should get me to CADH, and the disk light flashes), but a second Ctrl-Alt-Del does not reboot the machine, so it would seem that it is not in CADH. I need to hold the power switch for more than 4 seconds, to force a power off. After power on, the disks do the chkdsk.

On my IBM ThinkPad T43 (1871-W8M), it appears to suspend okay, but the screen backlight does not come on when I resume. This machine appears to be alive (other than the screen), and Ctrl-Alt-Del seems to go to CADH. A second Ctrl-Alt-Del does initiate a reboot, and the disks are clean when it does it.

FWIW, Doodle's screen saver also can't turn those two screens off.

The really sad part is, that I also have an ancient IBM ThinkPad A22e. It knows nothing about ACPI, but suspend/hibernate/resume works perfectly with the old APM. It is actually the BIOS, with a little help from the drivers, that does the suspend/hibernate/resume. The BIOS also turns off the screen, and turns it back on again, properly. It seems that the newer machines are losing capability, and ACPI can't turn on a light switch.