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Questions on cpu frequency scaling AMD vs. Intel
by Kai Schaetzl 04 Aug '08

04 Aug '08

I've been playing and comparing frequency scaling between AMD and Intel CPUs yesterday and there seem to be great differences between AMD and Intel and some gotchas. This is all on CentOS 5.2 with latest Xen kernels (which are supposed to be powersaving-enabled since 5.2). AMD: It seems once I get the AMD CPU to use the ondemand governor it works very well and very efficiently. But this is not set by default, one has to set ondemand explicitely in /etc/sysconfig/cpuspeed and run cpuspeed on bootup. Otherwise it just knows about userspace and performance and defaults to performance. Intel: On the other side ondemand is on for Intel CPUs automatically, but it doesn't seem to work. No matter if I run cpuspeed or not the current frequency is shown as 2000000. This is the scaling_min_freq for both CPUs I checked. The scaling_max_freq is 2.333/2.5. One is a Xeon Dual Core, one a Xeon Quad Core. With "not seem to work" for Intel I mean it doesn't act on demand as it should. I tested by gzipping and gunzipping a 4 GB image file. I used top to observe CPU utilization. With a dual core the idle percentage stays around 50% for a while and only goes below this threshold near the end of the operation. I deduce that means that gzip can make use of only one core and only when it comes to writing to disk or using other external tools it can utilize more CPU power because that task is taken over to the other core. Same observation with quad core (and 75%). There is no difference between AMD and Intel in this respect, but the task seems to run a bit more efficiently on an AMD CPU - e.g. it is able to max out idle at 0% at least for short periods while this is almost impossible to observe with the Intel CPUs. The timing also shows that the AMD is the fastest one. (The AMD, a very new low voltage X2, also runs at 2500 max.) My question: why don't the Intel CPUs don't scale up on demand? Could there be a bug in the driver that it measures overall utilization (which is at 50% most of the time) and not single core utilization, thus never reaching the threshold for scaling up? up_threshold is at 80 for both CPUs. (cat /sys/devices/system/cpu/cpu0/cpufreq/ondemand/up_threshold) I have a somewhat related question. That very new AMD CPU mentioned above was not recognized by CentOS 5.2 and the current frequency was shown as 800000 (instead of 2500000), although it was running in full speed. The latest kernel corrected this. It's still unknown, but the frequency is now calculated correctly and thus frequency scaling works now (it didn't work when it was miscalculating at 800000). On the other hand, I have an older low-voltage AMD CPU (probably about 2 years on the market) that is recognized as X2 3800+ but frequency scaling fails because it miscalculates the current speed to 800 MHz as well. Is there anything I can do about that? Where could I check whether this CPU should be supported in full and frequency scaling working? (I'm not sure, but I think it may have actually worked when it was running in a different motherboard.) Kai -- Kai Schätzl, Berlin, Germany Get your web at Conactive Internet Services: http://www.conactive.com

3 17

model_editor.py
by Bob Taylor 04 Aug '08

04 Aug '08

I have googled for this and also grepped the hplip sources without finding it. It is used to convert the models.dat file into models.xml. I need to insert my printer data into this file as it is not in the 5.2 hplip rpm. Could anyone help? I do not want to replace 5.2 rpm with a newer one. Thanks. Bob -- Bob Taylor

1 0

File system goes read-only once in a while
by Mufit Eribol 04 Aug '08

04 Aug '08

Hi, My Centos 5.2 server (5.1 suffered the same problem as well) has a logical volume on a RAID 10 array (4 SATA harddisks on a Highpoint RR2310 controller). /etc/fstab has an entry for this array as below /dev/raid_vg0/raid_lv0 /mnt/raid ext3 defaults 0 0 Normally it works OK. But, file system of "this volume" once in a while goes "read only" mode. The RAID software reports no problem with the hard disks. After reboot, the system comes back in normal rw mode. What could be the reason?. I would appreciate any help/hint. Thank you, Mufit

6 23

Fetchmail pop server and clean spam messages
by nightduke 04 Aug '08

04 Aug '08

Hi i want to fetchmail from a pop server and check every email to any rbl spamhaus,spamcop,etc and if match at any rbl the email will be deleted. It's possible to do this? Thanks Nightduke

4 4

GFS and Smaill Files
by Patricio A. Bruna 04 Aug '08

04 Aug '08

Hi, I had found on the list that i can improve the performance of GFS with small files if i adapt the size of the rsbtbl_size/lkbtbl_size values. But it also found that this has to be done after loading the dlm module, but before the lockspace is created. What means "before the lockspace is created", before the GFS partitions are mounted? How i do this? ------------------------------------ Patricio Bruna V. IT Linux Ltda. http://www.it-linux.cl Fono : (+56-2) 333 0578 - Chile Fono: (+54-11) 6632 2760 - Argentina Móvil : (+56-09) 8827 0342

1 0

Reloading /etc/hosts
by Robert Moskowitz 04 Aug '08

04 Aug '08

I am doing some testing and am having to make many changes to /etc/hosts Is there a way to reload the /etc/hosts file without doing a service network restart? I hope that in a while I can run BIND with a bunch of faked-out zone files (did this once to crack a Vonage PAP2). But for right now, I cannot introduce BIND to the equation....

4 5

Isolinux disk error 20; AX=4280, drive EF
by Ed Westphal 03 Aug '08

03 Aug '08

I thought I'd be clever and buy a DVD for 5.2 from LinuxOnline.biz. Well, just got around to trying it with the above results. Does the error mean I have a 'bad' DVD disk image? Please advise. Thanks.

4 8

Using CentOS 5 as server; best way to setup NFSv4?
by Ryan Dunn 03 Aug '08

03 Aug '08

I've got a server running CentOS 5.2 and has a working NFSv4 server. I've been looking for some help on this on the net, but haven't come across anything that looks like it would pertain to my situation. Basically, I've got a mixed distro environment (CentOS, Fedora, openSuSE, Ubuntu, Puppy, and yikes possibly a Windows box) on various desktops and laptops that I want to connect to my server. Currently, I've got it setup so that it is only NFSv4 with a host mask. My first concern is that it authenticates to the machine, not the user. Second, that the user is identifed by the UID on the local machine, not the actual user name. Since Centos/Fedora start UID at 500 and Ubuntu/opensuse start at 1000, even though the names are the same, UID is not. I'd rather not have to reID on half my machines Third, I know I'll need samba for the windows box. So, if someone were to get on my local network and have the same uid as I have, then they could mount my shares as rw and have at it. The ideal situation is that a user would logon to a local box, then when he wants to access a share, it sends the credentials to the server, and mounts the share. This is all for my home setup; basically, I'd like to have my directories be mounted rw for myself, but if i have guests over, have them be able to mount read only (sharing pictures with family memebers that have laptops, etc). Thanks, Ryan

6 14

Darwin Calendar Server on Centos 5
by dnk 02 Aug '08

02 Aug '08

Has anyone had any luck getting Darwin Calendar Server installed onto centos 5? Any tutorials anywhere? Dustin

1 0

'initrd' image of CentOS (domU) on Ubuntu (dom0)
by Admin Admin 02 Aug '08

02 Aug '08

Hello, What is the best way to get the xen enabled CentOS 5.2 vmlinuz and initrd images for use as a guest domain (domU) on Ubuntu host domain (dom0). Is there a site where these are available? I am hoping that I could use the vmlinuz from the latest kernel rpm, if I go that route, how could I generate the initrd image given that my host is Ubuntu? These are for use with post install of domU, which is setup using xen-create-image. Thanks

4 7

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