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Reliable Linux Laptop Vendor

by Mims Research

Hello, I'm very new to Linux and I'm not a technical person. But I've learned enough about Linux to know it rocks (thanks Bob!) and to know I want a new Linux laptop. Can anyone recommend a reliable vendor? Replies off list are welcomed. Thanks! Marie mimsresearch(a)gmail.com

Dec. 17, 2005

Re: [Wlug] logging level in syslog

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Gregory Avedissian wrote: > How do I increase the amount of information that gets logged in > /var/log/messages in suse 9.3? From what I can gather, I need to edit > /etc/sysconfig-ng/sysconfig-ng.conf.in. > > Is it just a matter of changing this line - > filter f_warn { level(warn, err, crit) and not filter(f_iptables); }; > > > To this? > filter f_warn { level(debug, info, notice, warn, err, crit) and not > filter(f_iptables); }; > > > Or would I edit /etc/sysconfig/syslog? > # Default loglevel for klogd > # > KERNEL_LOGLEVEL=1 > > If so, what number should replace "1"? > > Or something else? > > The reason I want to do this is to help a friend diagnose a problem with > lockups. Sometimes one program locks up, and sometimes the whole computer > locks up, and the reset button is the only way out. It happens when she > gets a lot of stuff running (e.g. several firefox tabs, several gedit > tabs, konqueror, and gimp-with many edits on the same file.) There's > nothing useful in the system log right before this happens. > > Thanks, > Greg > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > HI Greg, In my system (SuSE 9.2), in /etc/sysconfig/syslog, it mentions the log level for klogd. The man page for klogd describes the log level setting. The man page mentions "KERN_ERR", which I didn't know what that was, so I grepped for "KERN_ERR" in the Linux source code. I found it in linux-<ver>/include/linux/kernel.h (and if I had read the whole man page, I'd have learned this without grepping for it). #define KERN_EMERG "<0>" /* system is unusable */ #define KERN_ALERT "<1>" /* action must be taken immediately */ #define KERN_CRIT "<2>" /* critical conditions */ #define KERN_ERR "<3>" /* error conditions */ #define KERN_WARNING "<4>" /* warning conditions */ #define KERN_NOTICE "<5>" /* normal but significant condition */ #define KERN_INFO "<6>" /* informational */ #define KERN_DEBUG "<7>" /* debug-level messages */ Now, with regard to debugging lockups, I have had (unfortunately) some small experience with this. Here are some things to initially check: 1) run memtest for 24 hours and make sure the memory isn't flaky 2) make sure the motherboard has the most recent BIOS 3) setup a serial console to some other machine 4) enable more logging (you're trying to do that now...) 5) pray to $DEITY that the problem just goes away...forever! 6) make sure your hardware is properly cooled (CPU, video card, hard drives, etc) I hope this helps, Andy - -- Andy Stewart, Founder Worcester Linux Users' Group Worcester, MA, USA http://www.wlug.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDo18cHl0iXDssISsRAvxLAJsGFEzXNbUzMhBY9rSpuNsTv/8FHACePUwT jtBPDJBUMd4STQVfAQHICeY= =OxbA -----END PGP SIGNATURE-----

Dec. 17, 2005

logging level in syslog

by Gregory Avedissian

How do I increase the amount of information that gets logged in /var/log/messages in suse 9.3? From what I can gather, I need to edit /etc/sysconfig-ng/sysconfig-ng.conf.in. Is it just a matter of changing this line - filter f_warn { level(warn, err, crit) and not filter(f_iptables); }; To this? filter f_warn { level(debug, info, notice, warn, err, crit) and not filter(f_iptables); }; Or would I edit /etc/sysconfig/syslog? # Default loglevel for klogd # KERNEL_LOGLEVEL=1 If so, what number should replace "1"? Or something else? The reason I want to do this is to help a friend diagnose a problem with lockups. Sometimes one program locks up, and sometimes the whole computer locks up, and the reset button is the only way out. It happens when she gets a lot of stuff running (e.g. several firefox tabs, several gedit tabs, konqueror, and gimp-with many edits on the same file.) There's nothing useful in the system log right before this happens. Thanks, Greg

Dec. 16, 2005

Re: [Wlug] Success, almost, with GNOME

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Walt Sawyer wrote: > After last nights meeting, I figured that I'd use KDE. I've used KDE on > other machines and I liked it. Unfortunately, some stuff doesn't seem > to work. For instance, on my gnome desktop, when I plug in my external > USB hard drive, it shows up on the gnome desktop, but not on my KDE > desktop. While I could've gotten around that, it also cannot be found > in Konquerer, or even from a command line! That's the only thing I've > found so far. I did notice that some apps were there and working when > they didn't exist or didn't work on gnome. So I will keep using gnome > on my Fedora Core 4 laptop, until I find a better one. > Walt HI Walt, I'm not quite sure *how* to make it work, but I do remember having the functionality that you described in KDE. In fact, I remember turning it off(!) because I didn't care for it - gotta love the choices in Linux. ;-) However, I can't remember how I disabled it, either. My guess would be that this has something to do with hotplug and /etc/fstab for starters. I'm not quite sure about the KDE hook. Later, Andy > > > > > On Thu, 2005-12-15 at 16:09 -0500, Keith Wright wrote: > >>>From: Ken Jones <jonesj(a)ziplink.net> >>> >>>Per the suggestion of Chuck Anderson I logged in under a new >>>account. GNOME desktop worked just as it should. So I removed >>>all of the /home/kjones/.gconf directory and logged in again as >>>myself. >>> >>>Still it did not work correctly. In particular the right click >>>on empty space did not work. >>> >>>I did a "diff -r" on the two (now default versions I suppose) .gconf >>>directories. They seemed the same save for unique identifiers. Where >>>do I look to find the differences? >> >>Calls to xmodmap in your .bash*, .xinitrc, or startx setup files? >>If the buttons don't work in the program, maybe the >>program is fine, but somebody moved the buttons. >> >>This is just a random guess, of course. I have never seen >>an empty space on any desktop of mine. >> >> --Keith >>_______________________________________________ >>Wlug mailing list >>Wlug(a)mail.wlug.org >>http://mail.wlug.org/mailman/listinfo/wlug >> - -- Andy Stewart, Founder Worcester Linux Users' Group Worcester, MA, USA http://www.wlug.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDohcFHl0iXDssISsRAnerAJ4qMDqYC02Ps/yli2wQwXnOjSwPeACfQLN5 IXwjx3KnCK3j4LwYa47ALHk= =tR9B -----END PGP SIGNATURE-----

Dec. 16, 2005

Re: [Wlug] Success, almost, with GNOME

by Walt Sawyer

After last nights meeting, I figured that I'd use KDE. I've used KDE on other machines and I liked it. Unfortunately, some stuff doesn't seem to work. For instance, on my gnome desktop, when I plug in my external USB hard drive, it shows up on the gnome desktop, but not on my KDE desktop. While I could've gotten around that, it also cannot be found in Konquerer, or even from a command line! That's the only thing I've found so far. I did notice that some apps were there and working when they didn't exist or didn't work on gnome. So I will keep using gnome on my Fedora Core 4 laptop, until I find a better one. Walt On Thu, 2005-12-15 at 16:09 -0500, Keith Wright wrote: > > From: Ken Jones <jonesj(a)ziplink.net> > > > > Per the suggestion of Chuck Anderson I logged in under a new > > account. GNOME desktop worked just as it should. So I removed > > all of the /home/kjones/.gconf directory and logged in again as > > myself. > > > > Still it did not work correctly. In particular the right click > > on empty space did not work. > > > > I did a "diff -r" on the two (now default versions I suppose) .gconf > > directories. They seemed the same save for unique identifiers. Where > > do I look to find the differences? > > Calls to xmodmap in your .bash*, .xinitrc, or startx setup files? > If the buttons don't work in the program, maybe the > program is fine, but somebody moved the buttons. > > This is just a random guess, of course. I have never seen > an empty space on any desktop of mine. > > --Keith > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug > -- See http://www.goldmark.org/netrants/no-word/attach.html

Dec. 16, 2005

Re: [Wlug] Success, almost, with GNOME

by Keith Wright

> From: Ken Jones <jonesj(a)ziplink.net> > > Per the suggestion of Chuck Anderson I logged in under a new > account. GNOME desktop worked just as it should. So I removed > all of the /home/kjones/.gconf directory and logged in again as > myself. > > Still it did not work correctly. In particular the right click > on empty space did not work. > > I did a "diff -r" on the two (now default versions I suppose) .gconf > directories. They seemed the same save for unique identifiers. Where > do I look to find the differences? Calls to xmodmap in your .bash*, .xinitrc, or startx setup files? If the buttons don't work in the program, maybe the program is fine, but somebody moved the buttons. This is just a random guess, of course. I have never seen an empty space on any desktop of mine. --Keith

Dec. 15, 2005

Re: [Wlug] Re: Success, almost, with GNOME

by Jared Greenwald

Though normally I'm a supporter of Gentoo, it can be a little complex to install and keep up to date... You might want to check out edubuntu. (http://www.edubuntu.org/) Its actually specifically designed as a Linux distro for use with kids. -Jared On 12/15/05, Ken Jones <kjones(a)ziplink.net> wrote: > Thanks everyone. I am a KDE fan also. I went to GNOME as an > experiment. I have a memory leak problem with CORE 3 such that every > week or so I need to reboot. (soxview shows SWAP free space slowly > getting smaller and smaller) It turned out that this behavior is > independent of windows manager. > > A question. Whom do I contact at Red Hat to propose that they help the > Fitchburg Public School District migrate to LINUX server based "best > office practices"? > > Ken Jones > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 15, 2005

Re: Success, almost, with GNOME

by Ken Jones

Thanks everyone. I am a KDE fan also. I went to GNOME as an experiment. I have a memory leak problem with CORE 3 such that every week or so I need to reboot. (soxview shows SWAP free space slowly getting smaller and smaller) It turned out that this behavior is independent of windows manager. A question. Whom do I contact at Red Hat to propose that they help the Fitchburg Public School District migrate to LINUX server based "best office practices"? Ken Jones

Dec. 15, 2005

RE: [Wlug] Success, almost, with GNOME

by Gary Hanley

On Thu, 15 Dec 2005, Keller, Tim wrote: > Personally, I've moved away from gnome and I've been using xfce and I've > never been happier. I've just finished moving off of Gnome too. I didn't look into xfce but I'm happier with KDE than I was with Gnome. -- Gary

Dec. 15, 2005

RE: [Wlug] Success, almost, with GNOME

by Keller, Tim

Personally, I've moved away from gnome and I've been using xfce and I've never been happier. Tim. -----Original Message----- From: wlug-bounces(a)mail.wlug.org [mailto:wlug-bounces@mail.wlug.org] On Behalf Of Jared Greenwald Sent: Thursday, December 15, 2005 10:54 AM To: Worcester Linux Users Group Subject: Re: [Wlug] Success, almost, with GNOME On 12/15/05, Jeff Moyer <jmoyer(a)redhat.com> wrote: > ==> Regarding Re: [Wlug] Success, almost, with GNOME; Jared Greenwald <greenwaldjared(a)gmail.com> adds: > > greenwaldjared> What about .gnome or .gnome2 directories? There's always > greenwaldjared> restarting the X server with Ctrl+Alt+Backspace (that's > greenwaldjared> backspace, not delete). > > greenwaldjared> Not to start a flame war, but my personal recommendation > greenwaldjared> would be to switch to KDE, but I'm rather biased. KDE 3.5 > greenwaldjared> is really good. :) > > You're not alone in that recommendation. ;) > > http://lists.osdl.org/pipermail/desktop_architects/2005-December/000390. html I saw that the other day, but didn't want to drop the obvious "endorsed by..." tag line... :) _______________________________________________ Wlug mailing list Wlug(a)mail.wlug.org http://mail.wlug.org/mailman/listinfo/wlug

Dec. 15, 2005

Re: [Wlug] Success, almost, with GNOME

by Jared Greenwald

On 12/15/05, Jeff Moyer <jmoyer(a)redhat.com> wrote: > ==> Regarding Re: [Wlug] Success, almost, with GNOME; Jared Greenwald <greenwaldjared(a)gmail.com> adds: > > greenwaldjared> What about .gnome or .gnome2 directories? There's always > greenwaldjared> restarting the X server with Ctrl+Alt+Backspace (that's > greenwaldjared> backspace, not delete). > > greenwaldjared> Not to start a flame war, but my personal recommendation > greenwaldjared> would be to switch to KDE, but I'm rather biased. KDE 3.5 > greenwaldjared> is really good. :) > > You're not alone in that recommendation. ;) > > http://lists.osdl.org/pipermail/desktop_architects/2005-December/000390.html I saw that the other day, but didn't want to drop the obvious "endorsed by..." tag line... :)

Dec. 15, 2005

Re: [Wlug] Success, almost, with GNOME

by Jeff Moyer

==> Regarding Re: [Wlug] Success, almost, with GNOME; Jared Greenwald <greenwaldjared(a)gmail.com> adds: greenwaldjared> What about .gnome or .gnome2 directories? There's always greenwaldjared> restarting the X server with Ctrl+Alt+Backspace (that's greenwaldjared> backspace, not delete). greenwaldjared> Not to start a flame war, but my personal recommendation greenwaldjared> would be to switch to KDE, but I'm rather biased. KDE 3.5 greenwaldjared> is really good. :) You're not alone in that recommendation. ;) http://lists.osdl.org/pipermail/desktop_architects/2005-December/000390.html -Jeff

Dec. 15, 2005

Re: [Wlug] Success, almost, with GNOME

by Jeff Moyer

==> Regarding [Wlug] Success, almost, with GNOME; Ken Jones <jonesj(a)ziplink.net> adds: jonesj> Per the suggestion of Chuck Anderson I logged in under a new jonesj> account. GNOME desktop worked just as it should. So I removed all jonesj> of the /home/kjones/.gconf directory and logged in again as myself. jonesj> Still it did not work correctly. In particular the right click on jonesj> empty space did not work. jonesj> I did a "diff -r" on the two (now default versions I suppose) jonesj> .gconf directories. They seemed the same save for unique jonesj> identifiers. Where do I look to find the differences? I think you might want to poke around in the .gnome directory. Try the diff between the new user's .gnome and yours. jonesj> One other question. The Applications launcher on GNOME does not jonesj> contain the LOG OUT feature. I know the command "shutdown", but I jonesj> can not find a command to Log Out. Is there one? What is it? It's under the Desktop launcher on my Fedora system. -Jeff

Dec. 15, 2005

Re: [Wlug] Success, almost, with GNOME

by Jared Greenwald

What about .gnome or .gnome2 directories? There's always restarting the X server with Ctrl+Alt+Backspace (that's backspace, not delete). Not to start a flame war, but my personal recommendation would be to switch to KDE, but I'm rather biased. KDE 3.5 is really good. :) On 12/12/05, Ken Jones <jonesj(a)ziplink.net> wrote: > Per the suggestion of Chuck Anderson I logged in under a new account. > GNOME desktop worked just as it should. So I removed all of the > /home/kjones/.gconf directory and logged in again as myself. > > Still it did not work correctly. In particular the right click on empty > space did not work. > > I did a "diff -r" on the two (now default versions I suppose) .gconf > directories. They seemed the same save for unique identifiers. Where > do I look to find the differences? > > One other question. The Applications launcher on GNOME does not contain > the LOG OUT feature. I know the command "shutdown", but I can not find > a command to Log Out. Is there one? What is it? > > Ken Jones > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 15, 2005

Links from tonights meeting

by Frank Sweetser

Some of the links that were mentioned in tonights rambling meeting: isc.sans.org Internet Storm Center. A bunch of internet security professionals publishing a diary about major trends in online security. www.thedailywtf.com The Daily "What The F**k?" A programmer oriented blog of "Curious Perversions in Information Technology". -- Frank Sweetser fs at wpi.edu | For every problem, there is a solution that WPI Network Engineer | is simple, elegant, and wrong. - HL Mencken GPG fingerprint = 6174 1257 129E 0D21 D8D4 E8A3 8E39 29E3 E2E8 8CEC

Dec. 15, 2005

Re: [Wlug] getting that cpu to sleep ...

by brad

I looked into rt-linux. It appears that your real time process doesn't actually run as a process but as a kernel module. Unfortunately this would disrupt the flow of my program, but i'll keep this in the back of my head for the next version. Thanks for the suggestion. --Brad On Mon, Dec 12, 2005 at 09:26:51PM -0500, Keith Wright wrote: > > From: brad <maitre(a)ccs.neu.edu> > > > > > The immediate task at hand is that i want to get readings from > > an instrument (a light sensor) at a uniform interval, say every > > 1000 micro seconds. I have been able to achieve this task by > > setting up the loop i described above. However the loop above > > takes 99% of the CPU. I'd like to be able to achieve this > > without pegging the CPU at 99%. Does this make sense? if not i > > can try explaining it again, perhaps with some code. > > > > The kernel i'm running is 2.6.12. (well uname -r reports > > '2.6.12-9-686-smp.' its ubuntu's stock smp kernel.) > > You are doing something that Linux was not designed to do. > But don't despair, you are not the first one. > There is RT-Linux, (Real-Time Linux), which consists of > a real-time scheduler (meaning that it is designed to schedule > tasks with non-negotiable time constraints), which treats the > entire Linux kernel as a background task. > > Assuming your raw processor speed is sufficient (without which > you lose no matter what you do), the RT-Linux scheduler will > run your special task at guaranteed intervals, while any network, > disk I/O, web browsing, etc. that you need to do can use the > Linux system in the cracks between. > > Also the embedded Linux project and uCLinux (microComputer) > Linux might be interesting. Give any of these terms to > Google and get back more than you can read, but here is > a link to get started: > > http://www.linuxdevices.com/articles/AT3694406595.html > > > -- Keith > _______________________________________________ > Wlug mailing list > Wlug(a)mail.wlug.org > http://mail.wlug.org/mailman/listinfo/wlug >

Dec. 14, 2005

Reminder: Meeting Wed 14-dec-05 7:00 PM

by Andy Stewart

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 HI Everybody, Our next meeting is coming up really soon - this Wednesday, Dec 14, at 7:00 PM in the Access Grid room at WPI (lower level of Morgan Hall). I don't have any defined topic for the meeting, so I'm open to any ideas you might have. I have some flyers from Addison-Wesley & Prentice Hall which are for a 40% (yes, forty percent) discount on books purchased online prior to January 10, 2006. They will be available at this meeting. Also, I'll bring the following books for the zero cost raffle: Linux, Debugging and Performance Tuning Author: Steve Best Prentice Hall Apache Derby - Off to the Races Includes Details of IBM Cloudscape Authors: Paul C. Zikopoulos, Dan Scott, George Baklarz IBM Press That's about it - I look forward to seeing you at the meeting! Andy - -- Andy Stewart, Founder Worcester Linux Users' Group Worcester, MA, USA http://www.wlug.org -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.5 (GNU/Linux) Comment: Using GnuPG with Thunderbird - http://enigmail.mozdev.org iD8DBQFDnkIzHl0iXDssISsRAiR8AJ9D/L0X/Iak0TLPTt0dnA6Hgg288ACeMYdn zWNMvvBXjO7C9Cq6zSuPNH0= =enyh -----END PGP SIGNATURE-----

Dec. 13, 2005

Re: [Wlug] getting that cpu to sleep ...

by Keith Wright

> From: brad <maitre(a)ccs.neu.edu> > > > The immediate task at hand is that i want to get readings from > an instrument (a light sensor) at a uniform interval, say every > 1000 micro seconds. I have been able to achieve this task by > setting up the loop i described above. However the loop above > takes 99% of the CPU. I'd like to be able to achieve this > without pegging the CPU at 99%. Does this make sense? if not i > can try explaining it again, perhaps with some code. > > The kernel i'm running is 2.6.12. (well uname -r reports > '2.6.12-9-686-smp.' its ubuntu's stock smp kernel.) You are doing something that Linux was not designed to do. But don't despair, you are not the first one. There is RT-Linux, (Real-Time Linux), which consists of a real-time scheduler (meaning that it is designed to schedule tasks with non-negotiable time constraints), which treats the entire Linux kernel as a background task. Assuming your raw processor speed is sufficient (without which you lose no matter what you do), the RT-Linux scheduler will run your special task at guaranteed intervals, while any network, disk I/O, web browsing, etc. that you need to do can use the Linux system in the cracks between. Also the embedded Linux project and uCLinux (microComputer) Linux might be interesting. Give any of these terms to Google and get back more than you can read, but here is a link to get started: http://www.linuxdevices.com/articles/AT3694406595.html -- Keith

Dec. 13, 2005

Re: [Wlug] getting that cpu to sleep ...

by brad

On Mon, Dec 12, 2005 at 06:17:35PM -0500, Jeff Moyer wrote: > ==> Regarding [Wlug] getting that cpu to sleep ...; brad <maitre(a)ccs.neu.edu> adds: > > maitre> greetings, > > maitre> I have a question for those linux programmers out there. i'm > maitre> writing a program on linux (kubuntu to be specific) that requires > maitre> high-precision timing, somewhere on the order of 100 to 1000 micro > maitre> seconds. I get very good timing out of a loop written such that a > maitre> while() loop checks the system clock after every iteration and > maitre> comparing that to the desired wait time, like so (pseudo_code): > maitre> while(time_passed < wait_time) { time_passed = get_time() } ... > > maitre> The problem with this approach is that the process uses 99% of the > maitre> CPU since it just spins the CPU until enough time has expired. My > > The other problem with this is that you can be scheduled if your timeslice > runs out. > ummm, i didn't think about that one. > maitre> question: is there a way on linux (in C) to have the CPU sleep or > maitre> send it a no-op such that it's not just eating up cycles until time > maitre> expires? I have looked at nanosleep and usleep, however they appear > maitre> to only have precision to 10ms which too latent for my needs. > > As Mike pointed out, in more recent kernels you can tune the value of HZ to > get better granularity from select/poll. > Actually Mike's response reminded me of an article i bumped into about nanosleep on dragonflyBSD http://www.dragonflybsd.org/docs/nanosleep/ > What, precisely, are you trying to do and on what kernel? Perhaps with > more information we could provide better guidance. > The immediate task at hand is that i want to get readings from an instrument (a light sensor) at a uniform interval, say every 1000 micro seconds. I have been able to achieve this task by setting up the loop i described above. However the loop above takes 99% of the CPU. I'd like to be able to achieve this without pegging the CPU at 99%. Does this make sense? if not i can try explaining it again, perhaps with some code. The kernel i'm running is 2.6.12. (well uname -r reports '2.6.12-9-686-smp.' its ubuntu's stock smp kernel.) -brad

Dec. 13, 2005

Re: [Wlug] getting that cpu to sleep ...

by Bradley Noyes

On Mon, Dec 12, 2005 at 06:17:35PM -0500, Jeff Moyer wrote: > ==> Regarding [Wlug] getting that cpu to sleep ...; brad <maitre(a)ccs.neu.edu> adds: > > maitre> greetings, > > maitre> I have a question for those linux programmers out there. i'm > maitre> writing a program on linux (kubuntu to be specific) that requires > maitre> high-precision timing, somewhere on the order of 100 to 1000 micro > maitre> seconds. I get very good timing out of a loop written such that a > maitre> while() loop checks the system clock after every iteration and > maitre> comparing that to the desired wait time, like so (pseudo_code): > maitre> while(time_passed < wait_time) { time_passed = get_time() } ... > > maitre> The problem with this approach is that the process uses 99% of the > maitre> CPU since it just spins the CPU until enough time has expired. My > > The other problem with this is that you can be scheduled if your timeslice > runs out. > umm, i didn't think about that one. > maitre> question: is there a way on linux (in C) to have the CPU sleep or > maitre> send it a no-op such that it's not just eating up cycles until time > maitre> expires? I have looked at nanosleep and usleep, however they appear > maitre> to only have precision to 10ms which too latent for my needs. > > As Mike pointed out, in more recent kernels you can tune the value of HZ to > get better granularity from select/poll. > Actually Mike's response reminded me of an article i bumped into about nanosleep on dragonflyBSD http://www.dragonflybsd.org/docs/nanosleep/ > What, precisely, are you trying to do and on what kernel? Perhaps with > more information we could provide better guidance. > The immediate task at hand is that i want to get readings from an instrument (a light sensor) at a uniform interval, say every 1000 micro seconds. I have been able to achieve this task by setting up the loop i described above. However the loop above takes 99% of the CPU. I'd like to be able to achieve this without pegging the CPU at 99%. Does this make sense? if not i can try explaining it again, perhaps with some code. The kernel i'm running is 2.6.12. (well uname -r reports '2.6.12-9-686-smp.' its ubuntu's stock smp kernel.) -brad

Dec. 13, 2005

Re: [Wlug] getting that cpu to sleep ...

by Jeff Moyer

==> Regarding [Wlug] getting that cpu to sleep ...; brad <maitre(a)ccs.neu.edu> adds: maitre> greetings, maitre> I have a question for those linux programmers out there. i'm maitre> writing a program on linux (kubuntu to be specific) that requires maitre> high-precision timing, somewhere on the order of 100 to 1000 micro maitre> seconds. I get very good timing out of a loop written such that a maitre> while() loop checks the system clock after every iteration and maitre> comparing that to the desired wait time, like so (pseudo_code): maitre> while(time_passed < wait_time) { time_passed = get_time() } ... maitre> The problem with this approach is that the process uses 99% of the maitre> CPU since it just spins the CPU until enough time has expired. My The other problem with this is that you can be scheduled if your timeslice runs out. maitre> question: is there a way on linux (in C) to have the CPU sleep or maitre> send it a no-op such that it's not just eating up cycles until time maitre> expires? I have looked at nanosleep and usleep, however they appear maitre> to only have precision to 10ms which too latent for my needs. As Mike pointed out, in more recent kernels you can tune the value of HZ to get better granularity from select/poll. What, precisely, are you trying to do and on what kernel? Perhaps with more information we could provide better guidance. -Jeff

Dec. 12, 2005

Re: [Wlug] getting that cpu to sleep ...

by Mike Frysinger

On Mon, Dec 12, 2005 at 05:48:24PM -0500, brad wrote: > My question: is here a way on linux (in C) to have the CPU sleep or > send it a no-op such that it's not just eating up cycles until time > expires? I have looked at nanosleep and usleep, however they appear > to only have precision to 10ms which too latent for my needs. you cant unless you tweak the kernel HZ settings read this page: http://kerneltrap.org/node/464 -mike

Dec. 12, 2005

getting that cpu to sleep ...

by brad

greetings, I have a question for those linux programmers out there. i'm writing a program on linux (kubuntu to be specific) that requires high-precision timing, somewhere on the order of 100 to 1000 micro seconds. I get very good timing out of a loop written such that a while() loop checks the system clock after every iteration and comparing that to the desired wait time, like so (pseudo_code): while(time_passed < wait_time) { time_passed = get_time() } ... The problem with this approach is that the process uses 99% of the CPU since it just spins the CPU until enough time has expired. My question: is there a way on linux (in C) to have the CPU sleep or send it a no-op such that it's not just eating up cycles until time expires? I have looked at nanosleep and usleep, however they appear to only have precision to 10ms which too latent for my needs. Thanks, --Brad

Dec. 12, 2005

Success, almost, with GNOME

by Ken Jones

Per the suggestion of Chuck Anderson I logged in under a new account. GNOME desktop worked just as it should. So I removed all of the /home/kjones/.gconf directory and logged in again as myself. Still it did not work correctly. In particular the right click on empty space did not work. I did a "diff -r" on the two (now default versions I suppose) .gconf directories. They seemed the same save for unique identifiers. Where do I look to find the differences? One other question. The Applications launcher on GNOME does not contain the LOG OUT feature. I know the command "shutdown", but I can not find a command to Log Out. Is there one? What is it? Ken Jones

Dec. 12, 2005

Re: [Wlug] Problem with gnome, Fedora core 3

by Chuck Anderson

On Sat, Dec 10, 2005 at 03:58:05PM -0500, Ken Jones wrote: > Any ideas what controls this behavior and ow I can fix it? On a > different machine I have a Core4 system running GNOME perfectly. Try creating a new account and logging in to that one to see if the problem exists there. If not, then it is definately something in your user account, such as your gconf settings.

Dec. 10, 2005