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hyperthreading not detected by linux

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http://unix.stackexchange.com – I have a Dell server with two cpus, each cpu has 6 cores, and each core is hyperthreaded (i.e. should be equivalent to two virtual cores). I installed CentOS 6.2 on this server and it seems to detect only 12 cores (although there should be 24 virtual cores altogether). When I look at /proc/cpuinfo I get for each cpu: cpu cores: 6 siblings: 6 Which seems to indicate that number of cores equals number of virtual cores, or hyperthreading not detected/enabled. When I run dmidecode I can see that HT flag is turned on and I do see the following, which seem to indicate that the bios is configure (HowTos)

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Submitted by missing on 10/18/2012

Stories similar to hyperthreading not detected by linux

I have a Xeon E3-1230 processor, which has 4 physical cores, but has hyperthreading so an operating system running on it sees 8 logical cores.

I installed VMware ESXi and am creating virtual machines to run on it.

MAKEFLAGS -J value 20 weeks 1 day ago

skiwi wrote:Just use -jn with n the number of real cores you have. Note also the difference between "threads" and "cores". Threads are different items in /proc/cpuinfo, for the number of cores look at the number of different 'core id's in /proc/cpuinfo.

I've seen lots of people saying we should turn hyperthreading on on hyper-v hosts, but I've got a dilemma.

We're going to be running SQL Server 2012 Enterprise on a 2012 hyper-V cluster. This is licenced per core, and in a virtual hyperthreaded environment I think that core is a thread, not a full core.

I have a server with an Intel Core i7 processor (4 cores). If I view processor activity in Task Manager I see that there are 8 cores.

Hi,

I am very new to scripting and I wanted to write a unix shell script which can give me,

1)number of cpu's in a box

2)number of cores per cpu

3)total number of cores in abox (ie multiplying 1&2)

I am also trying to figure out how to check if hyper-threading is enabled in the server and also this check to script.

intially I am looking this to run on linux then wanted to implemen

Hi,

Could you please Tell me the command to find the number of cores in red hat box?

I have tried cat cat /proc/cpuinfo | grep processor | wc -l command to find the number of processers.

But need to fond the number of cores.

Is there any difference between core and processor?

Please help on this.

Regards, Vikas.

I have SQL Server 2008 Express running on Hyper-V based virtual machine with two vCPU-s. I've just been reading up on SQL Server 2012 Express and noticed that it's CPU is "Limited to lesser of 1 Socket or 4 cores" (http://msdn.microsoft.com/en-us/library/cc645993(v=SQL.110).aspx)

My question is how do the SQL Server 2012 limits on CPUs/Cores translate into vCPU-s?

No of CPU's and No of Core 16 weeks 6 days ago

I would like to understand how many number of CPUs and cores do I have on my server based on following out put..

Quote:

[root@xyz ~]# cat /proc/cpuinfo processor : 0 vendor_id : GenuineIntel cpu family : 6 model : 26 model name : Intel(R) Xeon(R) CPU X5570 @ 2.93GHz stepping : 5 cpu MHz : 1596.000 cache size : 8192 KB physical id : 0 siblings : 8 core id : 0 cpu core

I am trying to run my program in more than one core. I have 12 cores in my desktop and want the computer to use 1,2,3,4,......,11,12 one by one and want to test how the program performs in different number of cores. I tried using -t4 or -t 4 after the executable like.

./a.out -t4

but I cannot make sure whether its using exactly 4 or not.