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| Do you have preempt enabled in your kernel? |
| Yes |
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| No |
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| Total Votes : 168 |
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headache
Apprentice
Joined: 26 May 2004
Posts: 226
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 Posted: Fri Jul 09, 2004 5:39 pm Post subject: |
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| steel300 wrote: | | Malakin wrote: | | sindre wrote: | | Linux had preemptive multitasking from the start, don't confuse that with a "preemptive kernel". |
Windows NT also had preemptive multitasking from the start. (but has never had a preemptive kernel) |
Starting with Windows 2000, threads running in kernel mode can be preempted. The second link I gave you explains that. Yet my cries still go on deaf ears. Windows 2000 has a preemptible kernel. Two links as proof, and no refute, yet no one listens to me. |
I listen steel... Thanks for the links, interesting reading.
I have been running with preempt turned on in the kernel up until yesterday when i turned it off in 2.6.7-mm6 and so far I have not noticed any difference, not even while emerging kde 3.3 Beta1.
We'll see over time how it stacks up against earlier experiences with preempt.
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headache
Apprentice
Joined: 26 May 2004
Posts: 226
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| Posted: Fri Jul 09, 2004 8:21 pm Post subject: |
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Well, I'm a bit wiser now or maybe not.
I'm not sure what the problem is but while i was emerging kdemultimeda, something started to eat memory at an alarming rate and completly exhausted 1GB of RAM and 512MB ofswap making the system completly unresponsive.
I managed to kill off all programs. Switched kernel to the old one with preemption and rebooted. Loaded up the same programs as before and restarted the emerge process. Now everything is normal, i.e memory usage goes up and down but so far it has not exceeded 500M of RAM and no swap usage. Very strange.
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"I'd rather have a President who does it to a woman than one who does it to his country" -- Shirley Maclaine
Liberal (adj.): Free from bigotry; open to progress; tolerant of others. |
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aethyr
Veteran
Joined: 06 Apr 2003
Posts: 1085
Location: NYC
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| Posted: Fri Jul 09, 2004 8:51 pm Post subject: |
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darn you people gave me something else out to test this weekend.
I've been using preempt since it was available in Con's 2.4 patches, and I've never heard anything bad about it. Now all of a sudden it's not cool to run preempt in 2.6 :P
I'll have to ask people in #love-sources what they think (since I'm currently running that kernel). |
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floam
Veteran
Joined: 27 Oct 2002
Posts: 1067
Location: Vancouver, WA USA
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steel300
Veteran
Joined: 10 Jul 2003
Posts: 1155
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| Posted: Sat Jul 10, 2004 10:10 pm Post subject: |
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| Pwnz3r wrote: | | steel300 wrote: | | Malakin wrote: | | sindre wrote: | | Linux had preemptive multitasking from the start, don't confuse that with a "preemptive kernel". |
Windows NT also had preemptive multitasking from the start. (but has never had a preemptive kernel) |
Starting with Windows 2000, threads running in kernel mode can be preempted. The second link I gave you explains that. Yet my cries still go on deaf ears. Windows 2000 has a preemptible kernel. Two links as proof, and no refute, yet no one listens to me. |
I believe you about the preemptive kernel, however, after finding out that the system runs better without preemptiveness, it doesn't impress me. However, you said something about Windows being fast so I assumed that maybe Krusty in your avatar is smoking something besides a cigarette.  Unless your Gentoo installation was poorly setup, I don't see how it couldn't easily win a race against Windows of any version. |
Not all systems run better without preempt. The 2.4 kernels are much faster with preempt enabled. In the 2.6 kernels, preempt is no longer needed. Windows runs faster with a preemptible kernel. Just compare 9x to win2k.
My windows installation isn't bogged down by comstant compiles and upgrades of libraries I'm not sure I ever used. It boots faster (I timed it) and runs everything I need just as responsively as linux ever did. I know how to administer a linux and a Windows box. I do Windows by trade, and (used to use ) linux by hobby. I know how to make either of them run efficiently. The race is close as to whos faster, but its one of those things that we'll never know. I speak from experience when I say, for me Win2K is faster than linux.
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Rationality is the recognition of the fact that nothing can alter the truth and nothing can take precedence over that act of perceiving it. |
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playfool
l33t
Joined: 01 Jun 2004
Posts: 688
Location: Ã
rhus, Denmark
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| Posted: Sat Jul 10, 2004 10:34 pm Post subject: |
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-edit-
I was beaten to it.
Last edited by playfool on Sat Jul 10, 2004 10:48 pm; edited 1 time in total |
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neenee
Veteran
Joined: 20 Jul 2003
Posts: 1786
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| Posted: Sat Jul 10, 2004 10:40 pm Post subject: |
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thanks for reading threads you reply to 
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playfool
l33t
Joined: 01 Jun 2004
Posts: 688
Location: Ã
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| Posted: Sat Jul 10, 2004 10:46 pm Post subject: |
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| neenee wrote: | | thanks for reading threads you reply to |
shit happens, I missed that post.. anyways it seems to be in my Rawhide kernel at least, I think we should see this in -mm soon. And beloved user Redeeman seems to be on the case as well.. |
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placeholder
Advocate
Joined: 07 Feb 2004
Posts: 2500
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| Posted: Sun Jul 11, 2004 3:04 am Post subject: |
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| To just go a little off-topic.... Steel300, I was wondering why you still hang around here seeing that you no longer use Linux nor develop anything for it that I know of unless you are still doing something to the love source code. Are you having second thoughts or what? |
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Malakin
Veteran
Joined: 14 Apr 2002
Posts: 1692
Location: Victoria BC Canada
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| Posted: Sun Jul 11, 2004 3:36 am Post subject: |
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| Quote: | | In the 2.6 kernels, preempt is no longer needed. |
Preempt will always be needed for people who require low latency.
| Quote: | | I speak from experience when I say, for me Win2K is faster than linux. |
When people make statements like this I always wonder what specifically they're talking about is faster?
If you run Firefox in Win2k/xp or Linux I find it's faster loading in pages in Linux, I've timed it on identical machines and the WinXP system was fairly optimized (software wise). Now I'm not saying one is faster then the other as this is the only thing I've bothered to test. I think in general there isn't enough of a performance difference between Win2K/xp and Linux for it to effect what platform a person chooses (well a desktop user anyways). There are quite a few other reasons to choose Linux though, free is always nice and I find I can't live without some of the software - an example is I bought an ATI tuner card and remote and installed it in the WinXP system, had nothing but problems with ATI's software so I ended up moving it over to the Linux box and using Mythtv on it, works fantastic now. I could name a bunch of examples like this where Linux excells at something WinXP didn't handle so well.
| Quote: | | Windows runs faster with a preemptible kernel. Just compare 9x to win2k. |
These are two totally different operating systems though, it's not like win9x is the same as win2k except it doesn't have a preemptable kernel.
| Quote: | | My windows installation isn't bogged down by comstant compiles and upgrades of libraries I'm not sure I ever used. |
There's certainly nobody forcing people to update their software excessively, it's perfectly reasonable for someone to go a few months or longer between software updates. |
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placeholder
Advocate
Joined: 07 Feb 2004
Posts: 2500
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| Posted: Sun Jul 11, 2004 4:29 am Post subject: |
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| Yeah, you can go without software updates for a while with not much of a problem. However, I'd rather update every day than use an OS that doesn't even get needed security updates for a while. |
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playfool
l33t
Joined: 01 Jun 2004
Posts: 688
Location: Ã
rhus, Denmark
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| Posted: Sun Jul 11, 2004 10:43 am Post subject: |
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| Pwnz3r wrote: | | To just go a little off-topic.... Steel300, I was wondering why you still hang around here seeing that you no longer use Linux nor develop anything for it that I know of unless you are still doing something to the love source code. Are you having second thoughts or what? |
Same reason I hang around I guess, this is a good community, even if you don't worship Gentoo. |
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steel300
Veteran
Joined: 10 Jul 2003
Posts: 1155
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| Posted: Thu Jul 15, 2004 3:12 pm Post subject: |
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| Malakin wrote: | | Quote: | | In the 2.6 kernels, preempt is no longer needed. |
Preempt will always be needed for people who require low latency.
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Actually, preempt has a higher average latency. It just uses a more fair scheduling algorithm so the threads get proc time more evenly. It's the same concept as the CFQ I/O scheduler. It seems to be more responsive, but it really isn't.
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asph
l33t
Joined: 25 Aug 2003
Posts: 737
Location: Barcelona, Spain
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| Posted: Thu Jul 15, 2004 3:17 pm Post subject: |
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yes, absolutely 
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Malakin
Veteran
Joined: 14 Apr 2002
Posts: 1692
Location: Victoria BC Canada
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| Posted: Thu Jul 15, 2004 3:35 pm Post subject: |
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| Quote: | | Actually, preempt has a higher average latency. It just uses a more fair scheduling algorithm so the threads get proc time more evenly. It's the same concept as the CFQ I/O scheduler. It seems to be more responsive, but it really isn't. |
Average latency is not what matters, removing latency spikes is what's important. If you end up getting large latency spikes you'll have problems with things like audio/video recordings and playback. |
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