From Bugzilla Helper: User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1) Description of problem: I have installed RH 7.3 on Tyan i860 dual Xeon motherboard without any problems. I can run to instances of the same program at the same time (very long batch program for neural network computation): 1) they both run at the same speed as they individually run one a single processor motherboard 2) xosview shows the two processors working at 100% 3) lm_sensors show one processor at 42 degrees Celsius and the other at 49 degrees (box is 37 degrees inside) Up to that point everything is ok. Then I have updated the kernel from from 2.4.18-3 to 2.4.18-4 with red hat network because of the bug fix "kernel panic on smp system". Boot with new 2.4.18-4smp kernel: 1) xosview doesn't work anymore, even when reinstalled. 2) running to instances of the same program mentioned above at the same time provide a loss of performance of 50% in both programs sugesting that one processeur is not working 3) lm_sensors indicate that one processor is 37 degree (the other still 49) suggesting too that one processor is not working. Reboot with 2.4.18-3smp old kernel: 1) xosview is working, but indicates that there is FOUR processors ! 2) programs perfomances still bad 3) lm_sensors still show one processor at 37 degree xosview indicates that processors 2 and 3 are working 100% (processors 0 and 1 from 0 to 3%), but from time to time (not very ofen),without any action of my own, xosview indicates that processor 0 and 3 are working ` 100%; and at that point performances of the programmes turn back good, lm_sensors indicates that both processors are hot (42 and 49 degrees), and then things went back bad as before without any notice or action. More funny, I can run third instance of my program and xosview said there is three processors working at 100%... Version-Release number of selected component (if applicable): How reproducible: Didn't try Steps to Reproduce: 1. I don't want reinstall RH7.3 and upgrade again the kernel. 2. 3. Additional info:
Something went wrong in -4 that broke xosview. The actual work should be fine though, it's just the measurement program that gives the wrong data; top should also still provide the right info.
no, top doesn't still produce the right info.
I have found where the problem come from : the bios has Hyper-Thread enable ! I have just disbled it and everything ok. There is still one question now, why and how when there is already a process running on a physical processor the kernel choose to run a second process to the second logical processor attache to same physical processor the first process is already running on ? Is it a option or a command to force a task to run on a specific physical processor ? P.S. I found the answer of my problem in the support database of suse linux.
I am seeing double processors on xeon servers also. My kernel is 2.4.18-10 Does redhat consider this a bug?
no you see 4 virtual processors... you paid money to intel for the hyperthreading feature... use it! :)