Linux 2.6.7 falls into oblivion

meowsqueak · Posted: Mon Jul 26, 2004 2:29 am Post subject: Linux 2.6.7 falls into oblivion

Something very interesting just happened to me - I was compiling glibc and qt in parallel, and I lost almost complete control of my desktop. I tried changing virtual desktops (fbpager) and the system took about two minutes to 'undraw' the Evolution window, and another 6 minutes to draw five aterm windows. During which time, my mouse cursor was hardly mobile and I was unable to send keyboard or click events to anything. Couldn't even ssh in. The fluxbox clock froze so I was able to tell that my system was out to lunch for about 14 minutes

Luckily I sent the kernel into oblivion with a piece of elastic attached - one of my XOFF keyboard commands got thru to glibc (which was busy creating locales it seemed) and I regained control.

This is with Linux 2.6.7 and CONFIG_PREEMPT=y - I think I heard somewhere that using CONFIG_PREEMPT is a bad idea with 2.6.7 - can anyone elaborate on this please?

Pink · Veteran Joined: 24 Jul 2003 Posts: 1062

The preempt issue is ongoing - There is a seperate thread somewhere about that with reason why people do or don't use it (I don't - in any kernel).

It looks like you found the limitations of the stock scheduler - it's ok as standard but when compiling two things at once then all cpu time has been taken from X.

You may want to look at using a different scheduler such as np (Nick Piggin's) or staircase.

Staircase is easy to use - just emerge ck-sources, this is a stable and very responsive kernel by Con Kolivas. I would recommend this one.

Or try one of the love-sources - love uses Nick's scheduler but you'll have to renice X for it to work effectively. To be honest I use both (not at once!) and for ease of use, I would reccomend a simple emerge ck-sources (the latest is 2.6.7-ck5).

If nothing else, you can quickly see if ck has the same problems.

HTH

oberyno · Guru Joined: 15 Feb 2004 Posts: 467 Location: /bin/zsh

Some recent staircases have interactive disabled by default. If you are using a staircase based kernel, by all means enable this. It's at /proc/sys/kernel/cpusched/interactive .

Pink · Veteran Joined: 24 Jul 2003 Posts: 1062

Just to clarify, in case you are going to use 2.6.7-ck5, it is actually in /proc/sys/kernel/interactive and in this kernel defaults to 1 (i.e. on), so you don;t have to be concerned about it.

oberyno · Guru Joined: 15 Feb 2004 Posts: 467 Location: /bin/zsh

Oops. I guess the whole cpusched is part of hydra. And I guess it's hydra that disables interactive for me.

meowsqueak · Posted: Mon Jul 26, 2004 8:14 pm Post subject:

Thanks for the replies - at the moment I have disabled CONFIG_PREEMPT and my system 'feels' far more responsive (which theoretically is wrong I guess, but that seems to be how it is with 2.6.7), so I'll stick with that for now. If I get time, I'll try out some of those patchsets. Thanks again.