System speed questions

Jocco · n00b Joined: 03 Jul 2002 Posts: 24

First, I'm not ripping on Gentoo in any way. This has to be by far my favorite distro yet.

I've read how linux can be much fast than windows in many respects. My gentoo system seems to be slower than my WinXP system. Of course its all in the "user preference" But I would very much like to know the best compile options for my hardware / system.

I'm running...
AMD Athlon 1.2 ghz CPU
1gig SDRAM
Abit Motherboard
Geforce 2 GTS Pro
2 fourty gig 7200 rpm drives
Sony Cdrom
Mitsumi CDRW
ABIT K7TE Motherboard

X is really choppy especially when I'm compiling anything in the background. Another example, as I play and MP3, forget to pause xmms before running emerge, the MP3 starts to skip inevitably freezing linux. Could it be the nvdia driver installed while installing the stage3 tarball at gentoo installation needs to be updated?

Also, which kernel would be the best, as far as stability and speed, the gentoo sources or the linux sources?

What I would love to do, is install GCC 3.1, using the proper compile flags, and re-compile my entire system *grin* but not finding much of any information on how to properly upgrade from version 2.95.

One more question...has anyone been able to tell a noticable difference between Pentium and AMD gentooo systems? In so far as system speed and over all handling?

And last but not least, with a gig of SDRAM, what would be the optimum swap file to set up? Double the RAM would bring that too a 2 gig swap file, would that be applicable?

Thanks in advance.
J.

klieber · Posted: Tue Jul 09, 2002 1:26 am Post subject:

First thought -- make sure dma is enabled on your hard drive. Install hdparm if it isn't already and man hdparm for more information about how to determine if dma is enabled.

Second thought -- there are quite a few posts regarding optimizing for Athlons in the archives. You should start by searching there.

--kurt
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kcsduke · n00b Joined: 25 May 2002 Posts: 40 Location: Cambridge, MA

delta407 · Posted: Tue Jul 09, 2002 2:21 am Post subject: Re: System speed questions

burzmali · Apprentice Joined: 18 Apr 2002 Posts: 238 Location: ca

what kernel are you using now? i have no mp3 stutter during emerge or heavy disk usage at all. i am using gentoo-sources, i have found them to be very, very good. when i switched to gcc-3.1, i just wiped out my drive and started over from bootstrap. i figured i would probably end up doing that anyway if i tried to upgrade from 2.95. um, i guess that's all i have to offer. good luck.
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Spark · Tux's lil' helper Joined: 30 Jun 2002 Posts: 87

Don't forget to enable the lowlatency and preemtible options in the kernel before compiling, because default is disabled. With a preembtible kernel you really should get no mp3 choking (I have a P3-1000 and when my system is under such a heavy load that I can't do anything anymore, the mp3's are still playing fine) and no mouse choking either if you change the X priority (although I didn't test this long enough to be sure, but so far it didn't happen anymore whatever I try to compile).

shadowvcd · n00b Joined: 22 Apr 2002 Posts: 27

My system is a 350 pentium 2 with 512 mb ram. sometimes i use @ 200mb swap, sometimes i use 400 mb swap, but I've only seen the swap used about 3 times since I installed gentoo in April.

My machine runs much faster on gentoo than on windows xp. I do slow down considerably when I'm compiling, but I don't think gentoo compiling is a fair comparison to winxp running normal apps. Try compiling something under xp, and see how much other running apps slow down.

abhishek · Posted: Tue Jul 09, 2002 6:05 am Post subject:

for an athlon tbird u at leas want

Malakin · Posted: Tue Jul 09, 2002 8:33 am Post subject:

Unless you find it fun (heh), I wouldn't bother upgrading to gcc 3.1 yet, the speed increase is quite small and you migh run into lots of problems depending on what programs you use.

march=athlon* only means anything in gcc 3.1, in 2.95 march=i686 is the best you can do.

As was already suggested in the thread - make sure you have dma enabled and preempt. If you still get stuttering on your mp3's try a vanilla-sources kernel. You shouldn't get stuttering.

Ozymandias · Posted: Tue Jul 09, 2002 9:11 am Post subject: about speed

hi there, reading this was interesting.

first off, compiling for a specified platform or with -O2 or O3 hardly changes the speed of your apps, just a little, but I don't think enough to notice. Removing debug doen't speed up apps at all, except for startup times, because the binairies will be smaller. This stuff only pays off when compiling things like X or kernel, and perhaps glibc, the rest of the apps will be waiting more for syscalls then for their own code to be run. Only run intensive programs will benefit, raytraces, gimp etc.
If xmms and X jitters during building, make sure you have the low latency and preemptable kernel patch compiled in the kernel. Let X run with a lower nice value, and give xmms more buffer, kan be done from the preferences, and say it should load any file under 12 MB interely into the mem.
Little warning: -O3 kan cause incorect binairies, though most of the times it will do just fine. Gnome advices to compile it with O2.

second, windows is MUCH faster then linux, at least when it comes to GUI. We are stuck with X. It is a beautiful system, but a little bit of a hog, and then we don't have one GUI to consider and allmost everything is themable. Just try menu's: click in a the first menu and rapidely go to the last menu on the menubar, now try that in windows, and you see the difference. Though when using XP, the results will vary, depending wether XP was meant to run on the machine, and on the amount of animation in the GUI.
Don't get me wrong, I love linux, but microsoft has the advantage of having only one GUI which integrates winmanager and widgets, which makes a microsoft system much more consistent (and faster) which is a tremendous advantage.

last, about swapping, you don't really need swap if you have a gig of mem (wish I had) but it will swap, the kernel will reserve a certain amount of mem for caching block devices (cdrom hd etc.), about half the mem. So the more memory you have, the more it will reserve, giving this mem back later when there is demand for it. But if the kernel thinks that swapping is better then to free this cache, it will swap. If swap is unavailable it will simply schrink the cache.

greetz Ozy

kcsduke · n00b Joined: 25 May 2002 Posts: 40 Location: Cambridge, MA

arkane · l33t Joined: 30 Apr 2002 Posts: 918 Location: Phoenix, AZ

All of this is really odd considering I have a 450mhz Celeron running gentoo with KDE and I can have mozilla open, listen to an MP3 through xmms, and emerge and I barely ever have an issue.

If a 450mhz can do it (be it intel or not, that really shouldn't matter) then anything faster should be able to do it.

digitalnick · Posted: Wed Jul 10, 2002 6:12 am Post subject: Re: about speed

mdpye · Posted: Thu Jul 11, 2002 3:53 pm Post subject:

clacour · Posted: Thu Jul 11, 2002 10:08 pm Post subject:

Another option that can be useful in hdparm is to enable the "unmaskIRQ" stuff. It allows other things to do IRQ interrupts while the hard drive is working. It's recommended as a way to help smooth out X, so it might be applicable to your situation. (Warning, though: With modern hardware, it's not likely to do anything too nasty, but it might be a good idea to make all your filesystems read-only before turning it on the first time. It's always worked well for me, but as the infamous phrase goes, your mileage may vary.

The swap-space stuff depends entirely on what you're going to do with the box. If you're using it as a general-purpose workstation and mess-around-with-Linux box, the 1G alone will probably be ample. If you're planning to run a large website with a massive database, you might want to get another gig, and then make twice that much swap space.

At work a box with 4 gig of memory is not at all unusual, and if we tell the DBAs "You can have 3 gig for the database", they tend to react "Is that all?". Nobody can give you recommendations for how much memory you need (and how much swap) without knowing things like what programs you're going to run, how much data those programs will be dealing with, and how critical your response time is. Also, how much disk space do you have to play around with? If what you're going to do will take 4 or 5 meg, and running out of memory would be catastrophic, go ahead and give it 2 Gig (or even more).

(Since not that long ago a machine with 128M of RAM and 256M of swap was considered fairly beefy, I suspect you won't really need any swap at all -- you described a reasonably nice home machine, not an industrial-strength server.)

trythil · Posted: Thu Jul 11, 2002 10:13 pm Post subject:

Malakin · Posted: Fri Jul 12, 2002 1:58 am Post subject:

jnials · n00b Joined: 12 Jul 2002 Posts: 9 Location: Bertram, TX

Also be careful to understand that while linux doesn't require swap space with sufficient memory, other unix variants do.

-Jon

arkane · l33t Joined: 30 Apr 2002 Posts: 918 Location: Phoenix, AZ

I would hope that in the test that was done with that short stringcopying cpp file, the only difference was the -O2 and -O3. I changed the i variable to 100,000,000 and I got the following:
For -O2 optimized (no architecture at all, just -O2 optimizer)
real 0m28.136s
user 0m28.120s
sys 0m0.010s
and for -O3 optimization (same as above, except -O3)
real 0m27.811s
user 0m27.810s
sys 0m0.000s

I tried it several times, and it only varied by 0.010s. In the real world, this would be in several areas.. from string copying, virtual function inlining, etc. Would save a good deal (good deal being feeling a bit snappier, less bogged down).
It's not enough to turn a P2 133 into a P3 166, but it's enough to make the system feel "cleaner".

trythil · Posted: Fri Jul 12, 2002 6:41 am Post subject:

Oops, sorry, I misread. :oops:

tyreth · Posted: Fri Jul 12, 2002 4:21 pm Post subject:

trythil · Posted: Fri Jul 12, 2002 4:40 pm Post subject:

Yeah, it's GCC 3.1, running on an Athlon Thunderbird @ 850 MHz with 384 MB of RAM. I should have made that evident. (This is what comes of reading these posts on little sleep, I suppose.

)

Malakin · Posted: Sat Jul 13, 2002 5:46 am Post subject:

The difference between -O2 and -O3 in gcc 2.95 and 3.1 differ.

With 2.95 the only thing -O3 gives you over -O2 is -finline-functions.

With 3.1 you also get -frename-registers.

This would explain the difference between your results.

References:
http://gcc.gnu.org/onlinedocs/gcc-2.95.3/gcc_2.html#SEC2
http://gcc.gnu.org/onlinedocs/gcc-3.1/gcc/Optimize-Options.html#Optimize%20Options

Jocco · n00b Joined: 03 Jul 2002 Posts: 24

You guys rock, thanks for all the info!! Gentoo is awesome, if for no reason than the support. And talk about rock solid, this distro is the best I've seen yet. Still having some problems with speed, but with all the help and information in this thread, I'm sure this thing is going to fly in a week or two.

Unfortunatley, Im a busy guy and have little time to tailor Gentoo. I'll get it on. Oh yeaaahh...

Thanks again ppl.

J.

StrCrssd · Posted: Tue Jul 23, 2002 7:09 am Post subject: Gentoo Sources

I was having a similar problem on a P3-850 with 768M of RAM.

I suspected the issue may have been pre-empt (for no real reason), so I compiled the redhat kernel with low-latencey and no pre-empt, and things have gotten better.

Just thought I'd throw in my $.02
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