RE: Mersenne: 50% CPU?
Pentium 4's use hyperthreading to give you a 'virtual' second CPU. Don't bother trying to get another instance of Prime95 running on that 2nd CPU... It's virtual and while a lot of programs can benefit, the extreme workout that Prime95 generates means you won't get a benefit from running a second copy. It does mean that running a single instance as usual will, in theory, work even better because a lot more of the OS related things or if you use the computer to run Word, Excel or whatever will work better because those can now use the virtual CPU for a lot more things. And the reason it shows 50% is because Task Manager adds up all the CPU's and that becomes the 100% high mark. Since Prime95 is only using the first CPU, it can at most only use 50%. If you had multiple *real* processors and had Prime95 running on each one, it would come out to 100%. Hope that helps. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Quantum Mechanic Sent: Monday, November 03, 2003 8:13 AM To: [EMAIL PROTECTED] Subject: Mersenne: 50% CPU? I have an Intel 4 box from MDG, 1 CPU, 2.4GHz, 512MB RAM, L1 8KB, L2 512KB. Prime95 is only getting 50%, with System Idle Process taking 50%. It's currently running an LL test in the 20M range. Any ideas why it's only 50%? -QM = ~~ Quantum Mechanics: The dreams stuff is made of __ Do you Yahoo!? Exclusive Video Premiere - Britney Spears http://launch.yahoo.com/promos/britneyspears/ __ ___ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: 50% CPU?
Does your CPU have hyper-threading for sure, and it's enabled in the BIOS? Task Manager will show one graph per CPU... If you only see a single graph, your OS only thinks it has one CPU (counting all virtual and all real CPUs). I also assume you're using WinNT/Win2k/WinXP since Win98/ME doesn't support multiple CPU's (and doesn't really have Task Manager either...just that system resources thing). Check your list of running processes and see how many Prime95's show up. Should just be 1. If you have 2 running, yeah, running 2 processes on a single CPU, even with the multi-threading, will generally hamper how well either one runs. I once toyed with the idea of running LL tests on the real CPU and running factoring tests on the virtual one, but I never could decide if that was helping out at all...My gut tells me no just because of the memory accesses and not using the single L1/L2 caches on the CPU as well as they could be. By the way, that's a sight to behold when you have a quad CPU P4 system... 8 graphs happily bouncing away. I'm sure on an 8 CPU system it must be terribly impressive to have 16 graphs showing up, but I've yet to get my hands on such a system. :) I have a Pentium 4 processsor and TM indicates an average usage of close to 100% CPU for Prime 95 - am I running 'multiple instances' without being aware of it? If so, how do I prevent this if it will degrade efficiency? _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: 50% CPU?
I have a Pentium 4 processor and TM indicates an average usage of close to 100% CPU for Prime 95 - am I running 'multiple instances' without being aware of it? If so, how do I prevent this if it will degrade efficiency? Not all P4's have hyper threading not all motherboards support it on top of that. So it requires a HT enabled CPU, HT enabled Motherboard, HT supported OS for HT to function. From my experience HT is a nice feature since it gives Prime95 a chance to run even when other "not nice" programs are runningthat don't release the processor as often as they should even if it's not busy. The down side is with HT enabled Prime95 is more likely to interfere with certain performance sensitive applications. If you want to learn more about Prime95 HT there has been several recent posts on the topic at http://www.mersenneforum.org/forumdisplay.php?s=forumid=9 There is some evidence that running a LL (high usage of SSE2 floating point calculations) TF (high usage of SSE2 integer calculations) may increase overall throughput. Shane
Re: Mersenne: 50% CPU?
p4 with 400 or 533Mhz FSB do not support hyperthreading, *EXCEPT* the p4-3.06/533 does. P4 with 800MHz FSB (these are the C versions) do support hyperthreading. P4 Xeons all support HT. I have a question... gotta couple of dual P4/Xeon 2.8 servers, running linux 2.4.20 kernels... using two instances of mprime on them... any way to insure that the two instances run on actual different CPUs and not just two threads of he same CPU? per 'top`, they seem to have landed on CPU2 and CPU3 (out of 0-3) ooops, now they are on 1,2, which means they have NOT got locked CPU affinity.does anyone know which of the 0,1,2,3 CPUs are the physical ones? meaning, are 0,1 one cpu and 2,3 the other, or are 0,2 one and 1,3 the other? _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: 50% CPU?
Not all P4's have hyper threading not all motherboards support it on top of that. So it requires a HT enabled CPU, HT enabled Motherboard, HT supported OS for HT to function. Hmm... Yeah, I thought about that but I guess I just assumed he knew he had a hyper-threading CPU. Isn't it just the P4 Xeon's that have that? Obviously not all P4's have 'em. I have a P4 laptop and it doesn't have hyper-threading... Wish it did. The P4 Extreme Edition should be shipping now... Has the 2MB L2 cache and hyperthreading, just like the Xeon's do. http://www.intel.com/products/desktop/processors/pentium4HTXE/index.htm?iid =HPAGE+low_prod_031103 Yeah baby... Me wants one of those. :) PS - Oh... I just checked... I guess regular P4's do have hyperthreading as well, but only in certain models (2.4GHz or faster). My puny laptop is only a 1.7GHz P4. :( No hyperthreading for me. Here's a link to the Intel hyperthreading page: http://www.intel.com/products/desktop/processors/pentium4/index.htm?iid=ipp _htm+p4p _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
RE: Mersenne: 50% CPU?
p4 with 400 or 533Mhz FSB do not support hyperthreading, *EXCEPT* the p4-3.06/533 does. P4 with 800MHz FSB (these are the C versions) do support hyperthreading. P4 Xeons all support HT. Ahh... Good info. does anyone know which of the 0,1,2,3 CPUs are the physical ones? meaning, are 0,1 one cpu and 2,3 the other, or are 0,2 one and 1,3 the other? The standard way to identify is to have all physical CPU's listed first (0,1 in a dual CPU system) followed by the virtual CPU's (2,3) Prime95's INI file lets you set the affinity, so look in the settings of the program to set that to the physical processors. I can only vouch for Win32 and how it numbers the processors, but I seem to recall that Linux numbered them the same way... All physical followed by all virtual. I could be wrong though. I sometimes am. :) _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: 50% CPU?
The standard way to identify is to have all physical CPU's listed first (0,1 in a dual CPU system) followed by the virtual CPU's (2,3) Hmmm, looks like you are wrong... /proc/cpuinfo shows cpu 0,1 as being one physical id, and cpu 2,3 as being the other.. # cat /proc/cpuinfo processor : 0 physical id : 0 processor : 1 physical id : 0 processor : 2 physical id : 3 processor : 3 physical id : 3 (much kruft deleted) Prime95's INI file lets you set the affinity, so look in the settings of the program to set that to the physical processors. I can only vouch for Win32 and how it numbers the processors, but I seem to recall that Linux numbered them the same way... All physical followed by all virtual. I could be wrong though. I sometimes am. :) I don't know if the affinity stuff will work in linux, however... I found some kernel patches that ADD cpu affinity support to linux, but it was only folded into the master source as of 2.5.8 (and, presumably, 2.6.x) and I'm running 2.4.20 on these servers. I don't really want to mess with patching the kernel on these RD servers, they are being used for database development. meanwhile, watching the CPUs in TOP, the 2 instances are bouncing all over them every few seconds. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: 50% CPU?
At 04:35 PM 11/3/2003 -0800, John R Pierce wrote: I don't know if the affinity stuff will work in linux, however.. Mprime ignores the affinity settings in the ini files. We'll have to add it when linux 2.6 is released. _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
Re: Mersenne: 50% CPU?
--On Monday, November 03, 2003 5:08 PM -0800 John R Pierce [EMAIL PROTECTED] wrote: George Woltman wrote: At 04:35 PM 11/3/2003 -0800, John R Pierce wrote: I don't know if the affinity stuff will work in linux, however.. Mprime ignores the affinity settings in the ini files. We'll have to add it when linux 2.6 is released. kernel 2.6 has been 'released' for some time now. however, Red Hat just announced they are discontinuing all support and future development for Red Hat Linux effective almost immediately (Dec31 2003 for RH 7.x and 8.0, and april 31 2004 for RH 9.0), instead offering Red Hat Enterprise 3.0, which costs $$$ per system. I don't know if Kernel 2.6.x has made it into any of the other mainstream distros yet. Essentially they are discontinuing it under that name, but merging it into the Fedora distro (a fully redistributable, open source distro based on RH). It is simply no longer going to be called Red Hat Linux. There's some speculation that they may be using Fedora for testing code that's not known to be stable before including it in their enterprise distro, but that's not the end of the world - anyone can install any old rpm version they feel confident in. See the thread I started at http://slashdot.org/comments.pl?sid=84550cid=7379004 for more than you wanted to know about the whole thing. Nathan _ Unsubscribe list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ -- http://www.tasam.com/~lrwiman/FAQ-mers
