Gentoo Latency

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

I'm new to Gentoo, and the install went smoothly enough. But now I've got a working system I'm finding that the performance is rock bottom.

For instance when I'm compiling something, running X, KDE3, and so on I get periods of between 1 and 12 seconds where the machine locks up, no mouse movement, no screen update, sound skips etc. Rather nasty for a so called 'pre-emptive operating system'. I previously had Mandrake installed (yeah I know, I know) and it didn't suffer from this sort of lockups (as much, sound would never skip).

So what can I do to smooth things out a bit. 12 seconds of no action is unbearable... it completely stops my work flow.

FYI
- Althon 1.4 running at 1.2 on 100 fsb
- 256mb ram
- Gentoo stage3 install, i686 kernel, Kde3, Alsa/SbLive

Help!
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Matt

T2 · n00b Joined: 01 Jun 2002 Posts: 67 Location: Slovenia

You may try compiling vanilla kernel sources or compiling all stuff from stage1, Which motherboard, video card do you have?

lx · Posted: Mon Jun 03, 2002 2:42 pm Post subject:

You could also try to use the mandrake kernel (or at least same configuration and relevant patches).
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TGL · Posted: Mon Jun 03, 2002 3:54 pm Post subject:

Just a thought... do you have some kind of power management (APM or ACPI) enable ? If yes, maybe you should try to turn it off. (In fact, I'm wondering if some hardware wake-up can freeze your computer during a few seconds. But I'm really not sure of that.)

Zu` · l33t Joined: 26 May 2002 Posts: 716 Location: BE

DMA enabled on your harddisk(s)?

And compiling from stage1 might be better, also follow optimalisations for building KDE, you can find them on the forum here somewhere.

Safrax · Guru Joined: 23 Apr 2002 Posts: 422

Perhaps you didn't enable the low latency and pre-emptive kernel options when configuring your kernel. Or at least thats what it seems like your problem is to me.

Malakin · Posted: Mon Jun 03, 2002 8:03 pm Post subject:

I'd suggest trying vanilla sources.

Running without dma won't give you 12 second periods of no response, neither will not having preeempt/low latency.

There seems to be quite a few people complaining about this sort of thing in Gentoo.

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

Vanilla kernel: Sure I'll give it a try. Anyone know what I'll lose in doing so? I.e. why use a gentoo kernel in the 1st place?
PS I've compiled the kernel several times now, just to get the right combination of modules and features. So for a windows luser I'm getting the hang of this Linux thing ;)

Video card: G400
Motherboard... um I forget, I'll find out. (I didn't actually buy it, I got given it).

DMA: Well the speel of text that I see on startup mentions that all the HD's are using DMA but a) I didn't read it carefully as it scrolls past @ speed and b) it's probably not authoritative. So anyone know how to find all the boot up status text after you've booted? And what is the definitive way to check whether your accessing HD's using DMA? I selected all the "DMA" type stuff in the kernel config so I'm hoping it's working. Originally I had 128mb ram and I thought the machine was swapping a lot (which usually borks performance up royally) but I grabbed another stick of 128 out of my 2nd machine and dumpped it in there, dropped the FSB down to 100mhz (stupid PC133 won't actually RUN at 133). And everything seems stable but the freezing is still there or worse. I've yet to test the transfer speed of the HD, which is probably the best way to tell if DMA is on or not. PS I don't actually know how to test the throughput of HD's under Linux short of writing a program myself to do it. Hmmm.

Low-latency/Pre-emptive patches: Well I'd like to think that a stock kernel should have reasonable performance before I go tweaking the heck out of it. I would like to try these patches some time, but I want to know that I'm building on a solid foundation first. And I don't have that yet.

Anyway all good responses. I'll keep reading and posting here. Thanks
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Matt

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

The guys in this forum are discussing the same problem:

https://forums.gentoo.org/viewtopic.php?t=3767

Sorry, shouda searched before I posted. Seems it's only related to AMD based systems running KDE. Now I'm sticking with KDE and my AMD processor, it remains to be seen exactly whats foobaring up the performance.
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Matt

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

I found this:

http://www.uwsg.iu.edu/hypermail/linux/kernel/0110.2/0399.html

It might be a possible solution to my problems. He seemed to have had very similar issues.

I now have to track down that patch and find out whether I already have it or I need to get it etc etc.
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Matt

c_kuzmanic · Posted: Wed Jun 05, 2002 10:15 am Post subject: Re: Gentoo Latency

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

I have 2 sticks of RAM, one 128mb PC150 stick and another 128mb PC133. When I run both sticks at 1.4 ghz / 133 FSB the machine isn't stable. So I docked the speed in the BIOS to 1.2ghz / 100 FSB and it works like a charm. Windows is rock solid (no choppy performance) and so is gentoo (with choppy pre-emptive performance).

Personally I'm always worried that running the one stick of 128mb PC150 at 1.4ghz is going to be swapping some of the time, so I went for the 2 sticks at a lower speed.

The one stick of PC150 behaves pretty much the same under Gentoo at full speed. So I doubt that is effecting things.
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Matt

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

Oh my motherboard is an Abit KT7A RAID. I'm not using the RAID so thats not an issue.

Also I think maybe I should try the hogstop + eatcache patches:
http://www.uwsg.iu.edu/hypermail/linux/kernel/0110.2/0399.html

But I've run out of time till friday.
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c_kuzmanic · Posted: Wed Jun 05, 2002 11:59 am Post subject:

I have that motherboard in one of my machines. Never had a prob. Did you try running that machine without that stick (PC 150)? That motherboard does not offcially support that stick if my memory serves me right, but it should be downward compatible, is it?. And again is that an athlon xp you're running on that abit kt7a raid board? To my knowledge that board does not support ahtlon xp's either. This is from the abit site:

CPU
Supports AMD Athlon/Duron 600MHz-1.2GHz 200/266MHz FSB Socket A Processors <----NOT athlon xp's only the late generation T-Bird athlons with 266fsb are supported (my edit)--->

But maybe you have a late generation T-Bird with 1.4 GHZ and 266 fsb? It would be great if you could shed light on the issue.

Malakin · Posted: Wed Jun 05, 2002 6:21 pm Post subject:

friedmud · Posted: Wed Jun 05, 2002 6:44 pm Post subject:

This problem is almost always related to not having DMA (or UDMA) access turned on for your drive. Make sure you compiled in DMA into your kernel and make sure you selected your right controller chip in your kernel configuration.

I repeat! Anyone having this problem - this is ALMOST ALWAYS RELATED TO INCORRECT DMA SETTINGS!

Try using hdparm if you are sure your kernel is configured correctly - you can manually set DMA settings with hdparm.

Derek

FINITE · Guru Joined: 10 May 2002 Posts: 449

hdparm can be used to turn on dma and 32bit access etc. but you would be better off to compile support for your chipset into the kernel proper. Unless your chipset is not TRUELY supported.

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

Malakin:
My bios can use different multipliers so to get 1.2ghz I set it to 100mhz FSB * 12 = 1.2ghz.

With one or 2 sticks of ram the results are the same, so thats ruled out.

I'll check the whole DMA thing and post results tomorrow.

As for the CPU, it doesn't have 'Xp' on it, I think it's the last of the normal Althons. Also I flashed the bios with the lastest from Abit so while initial support probably didn't know about the CPU I've upgraded it so that it shouldn't be a problem.
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Matt

jtanner · Posted: Thu Jun 06, 2002 3:56 am Post subject:

I agree that the problem is probably not having dma turned on for your hd.

Dibrom · n00b Joined: 03 Jun 2002 Posts: 4

c_kuzmanic · Posted: Thu Jun 06, 2002 6:56 am Post subject:

I wish I could do something to replicate any of these probs, but my hardware runs fine. I run a custom kernel with only the preemptive kernel patch applied, since the combination of both low latency and pre-emptive gave me problems with stabilty.

tkdack · Posted: Fri Jun 07, 2002 12:59 am Post subject:

Just to throw another one into the mix....

Do any of you guys having problems have fam enabled/started?

fam is used by KDE (and Gnome I think) to monitor files and directories. It is a deamon that KDE uses instead of utilising a large number of performance expensive system calls to monitor files.

Try running:

fret · n00b Joined: 03 Jun 2002 Posts: 8 Location: Australia

Argggghhh:

/dev/hda:
Timing buffered disk reads: 64 MB in 41.34 seconds = 1.55 MB/sec
/dev/hdb:
Timing buffered disk reads: 64 MB in 68.49 seconds =956.87 kB/sec
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Matt

Sivar · Apprentice Joined: 25 May 2002 Posts: 266 Location: USA

Dibrom · n00b Joined: 03 Jun 2002 Posts: 4