Questions tagged [hyperthreading]

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Benefits of hyperthreading for multiprocessing?

I'm managing a compute node in a HTC cluster. The node is a 56 cores / 112 threads dual Xeon machine, and the typical workload consists of many instances of single threaded Monte Carlo simulation jobs....
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6 votes
1 answer
880 views

EC2, Windows 10, half of the virtual processors

We run t3.large and m5.large instances, which have 2 vCPUs (as displayed in the EC2 management console). I'm trying to understand why the Windows 2019 (AMI provided by my IT) can only see half the ...
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Why did disabling hyperthreading make my server slower?

I have a server that's primarily running a Ruby script. Because Ruby (2.7) has a GIL, it is single threaded. My computer (server) has an Intel i3 dual core processor, but due to hyperthreading I see ...
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-2 votes
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Maria Performance Tuning: HyperThreading is great for marketing, lousy for performance [closed]

I'm looking into optimizing my database server and this is what I read in Maria's official documentation here. How true is this? More so, how is this true? Apologies if this is not the best place ...
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Is it possible to have a partial hyperthreading with a Linux System?

I have a server with 2*14 cores with Hyperthreading enabled. This means I have (2*14*2=28*2) 56 vCPUs. [root@supervision1 /]# dmidecode -t 4 | egrep 'Socket Designation|Count' Socket Designation: ...
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How to properly configure ESX VMs to use hyper threading in a usefull way?

I've a kind of specific question that I was unable to find an answer for in the official documentation of VMware or on some other very useful threads here on this platform, so here it is: I've got a ...
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2 answers
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Identical Processor - Live Migration Error

I have production problem thats why Im asking for fast help :/ Environment 2 new HyperV Host with Windows 2016 in Failover Cluster Both with CPU: Intel® Xeon® Silver 4116 Processor 2.10 Ghz Live ...
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0 votes
1 answer
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Enabling Hyperthreading on a Centos 7.3 server using Intel Xeon E5620

I have a Centos 7.3 server running a dual socket quad core Intel Xeon CPU E5620 @ 2.40GHz. I would like to use hyperthreading on this server but it seems it has been disabled. The spec sheet for ...
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0 votes
2 answers
186 views

Understanding Intel HTT

System 1: Notebook Detect the installed CPU: $ cat /proc/cpuinfo | grep "model name" | head -1 model name : Intel(R) Core(TM) i5-2520M CPU @ 2.50GHz The data sheet says: no. of Cores 2 no. of ...
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2 votes
2 answers
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KVM: Which CPU for VM ('host' vs 'kvm64') to use for web load?

Playing with Proxmox 5.0 as a hypervisor platform and set up KVM VM to serve website, I really wonder if I should use kvm64 "virtual" CPU or try to use host. To be specific, I have an 4-...
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1 vote
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What performance statistics can I use to determine if hyperthreading will improve performance?

There are several questions asking if disabling hyperthreading will improve performance (e.g. like this). The answer (as it is to all performance questions) is of course "profile it on your workload"....
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6 votes
3 answers
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VMware / SQL - physical vs logical cores - how many vCPUs to assign when HT is enabled

We have a ESX host: It has 2 CPU x 8 cores each, and HT enabled. So, total 16 physical cores or 32 logical cores. It has a single dedicated SQL VM on it (no other VMs run on this host), and it has ...
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4 votes
1 answer
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Turning off HyperThread by BIOS or kernel?

Is there any performance difference between these disabled HyperThread scenarios? Which is the best, and why? Disable HT in BIOS Use noht kernel parameter The high-optimized parallel applications ...
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0 votes
1 answer
258 views

ESXi hyper threading numbering for affinity settings

I have server that contains 2 physical socketed Xeon CPUs. Each Xeon has 6 cores, so with hyperthreading disabled on one server I have CPUs 0-11. If I enable hyper threading, I was under the ...
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1 answer
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How vCPUs are calculated?

Yesterday I contacted my vendor to buy a server, and I asked them how I should calculate the CPU and RAM requirements for my server, given that I want to create multiple virtual servers on it He said ...
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24 votes
4 answers
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How many CPUs should be utilised with Hyperthreading?

Let's say I have a server cpu with 18 cores, with hyperthreading on, which means I can see 36 cpus in htop. To fully utilise the CPU and not impact single-thread performance, should I be aiming for ...
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Should I disable hyperthreading? [closed]

I have a large job and I'm experimenting with the topology to see what gives better results (playing with ntasks, ncores-per-cpu, nodes, etc.) I'm using slurm as my work queue manager. I have two ...
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5 votes
1 answer
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CPU parking, windows 2012r2, with no hyper threading

I have server based on Intel R1304WT2GS with two e5-2660v3, windows 2012r2. I've installed last drivers from intel site. For business purposes i need to disable hyper threading, and use windows 8.1 / ...
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6 votes
3 answers
4k views

VMware CPU Hyper Threading Scheduling Affinity

I have looked everyware and read a bunch of documentation on this but haven't found a direct answer so here it goes: There is a setting in the "Resources" Tab in vCenter that lets you configure Hyper-...
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1 vote
1 answer
863 views

What can explain Hyperthreading bringing a server to its knees

In the last year I've had 2 brand new servers that I commissioned where their performance made them unusable. The both servers were Dell R620 servers with 1 processor. One had 6 cores and the other ...
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5 votes
1 answer
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AWS EC2 instance hyperthreading

I am currently doing some performance testing of web-apps that we have moved to AWS. One of the things we have noticed is that vCPU performance doesn't seem to be nearly as good as we'd expected. In ...
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3 answers
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Does hyperthreading on client PCs have any impact on network performance?

My knowledge of networking is pretty minimal, and my hardware knowledge is only slightly better so please bear with me. I work for a small non-profit that's getting a new computer network set up by ...
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1 vote
1 answer
356 views

intel 2620 and 2609 on debian cpuinfo [closed]

I have two Boxes running Debian 7 with the following processors. Each Box has two of the same processors. Intel® Xeon® Processor E5-2620 (15M Cache, 2.00 GHz, 7.20 GT/s Intel® QPI) # of Cores 6 # ...
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What are the performance implications of Hyper-threading for single Nehalem+ CPU? [duplicate]

I am choosing between two models of servers, the major difference between them being the the availability of Hyper-Threading. Servers in question are SYS-E32-1 and SYS-E32-3 from So you Start (an OVH ...
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1 vote
1 answer
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how does cache work on hyperthreaded Intel Xeon Processors

I am running some experiments on a research database on EC2 using a c1.xlarge instance. As far as I can tell, the c1.xlarge uses 8 hyper-threaded virtual CPUs. Amazon also says that this instance uses ...
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-1 votes
2 answers
184 views

Multi-CPU server with CPUs of differing core counts

Is it possible to have a multi-CPU server where the CPUs do not necessarily have the same number of core counts? For example, a group of 4 at dual core and a group of four at quad core? This ...
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3 votes
1 answer
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Linux Load Averages and HyperThreads

My rough understanding of a Linux load Average is that for every integer a CPU core is working all the time. For example, 1 means on a 4 core system that 1 core is working at capacity. How does ...
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2 votes
1 answer
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How to make Windows 2008 R2 see 4 CPU cores, with two single core processors , Hyperthreading enabled

I had server with old Xeon DP and Windows 2008 R2 , With hyperthreading enabled OS saw 2 CPU cores. Recently I've added second same Xeon DP , but OS steel sees 2 CPU cores. I did uninstall all cpu's ...
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0 votes
1 answer
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Maximum CPU and hyperthreading [closed]

Hyperthreading doubles the logical cores, but doesn't double CPU resources. Linux measure CPU usage in %, allocating 100% points for each thread, thus reporting a maximum of 800% for a quad-core CPU ...
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1 vote
2 answers
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Hyper-V, Hyperthreading, and the implications of per-core licensing [duplicate]

Possible Duplicate: Hyper-V and Hyper-threading: On or off? Can you help me with my software licensing issue? I've seen lots of people saying we should turn hyperthreading on on hyper-v hosts, ...
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6 votes
1 answer
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Enabled hyperthreading - causes qthread creation error on Ubuntu Precise 64 bit

We recently set up an HP ProLiant DL360p server for some heavy grunt-work. For one reason or another we disabled hyperthreading in the system BIOS when setting it up. Being a dual-CPU 8-core system, ...
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  • 353
2 votes
1 answer
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Hyper-Threading & htop/system-monitor

I'm running a large set of simulations on a quad-core Xenon E5520 with Hyper-Threading enabled. My software automatically detects 8 (virtual) cores and launches 8 simulations to run in parallel. ...
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2 votes
4 answers
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Should I expect a great increase in Oracle performance in terms of handling multiple requests switching from single to dual core?

We have an Oracle database of roughly 100 GB that runs on top of a Windows Server 2k3R2 VM in ESX in a 1 socket, 1 core configuration. Whenever it has to handle a major query it seems to get "pegged" ...
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6 votes
2 answers
4k views

Nginx worker_processes and multi core cpu's - Do Hyper-threading cores count?

Quite often, when reading about the recommended worker_processes for nginx it is stated that this should be set to the numbers of cores the server hosting nginx has. We were wondering if we should ...
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-4 votes
1 answer
160 views

Hyperthreading can only create two threads? [closed]

HyperThreading can only create two cores/threads ? More can not be created by design or is there any other limitation ?
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1 vote
2 answers
2k views

VMware ESXi Virtual Machine configuration for hyperthreading

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 ...
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2 votes
1 answer
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CPU Resource pool with and without hyperthreading in vmware esx/esxi

VMWare ESX/ESXI running with AMD 12core @2.2GHz. Intel 6core @2.4GHz In resource pool, with amd cpu I should see 26.4GHz available. Now it's interesting what will be shown with Intel CPU? Am I gonna ...
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  • 301
15 votes
3 answers
27k views

Hyper Threading and Virtual Machines?

I already looked at this thread: Hyper-V and Hyper-threading: On or off?, but the only answer is Windows specific.... I am building a VM server (using Proxmox VE if that makes a difference) and was ...
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2 votes
3 answers
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Optimal number of threads for compute-intensive task on server with Hyperthreading

When running a compute-intensive task on a server with an Intel i7 quad-core processor with Hyperthreading, is it ideal to run eight threads (for the eight virtual cores), or only four (for the four ...
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1 vote
2 answers
716 views

Hyperthreading on multicore processors - is it of any use? [closed]

I know hyperthreading from the time long ago where the processors used to have only a single core. The technology was really usefull then. Right now, Intel is still offering hyperthreading with 6-core ...
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2 votes
2 answers
6k views

Why would only half of the cores on my hyperthreaded linux server be loaded?

I have a server which is a 12 core hyperthreaded system, which means I have 24 virtual cores. I'm running 24 processes on my server, each listening on its own port and doing the same things, albeit ...
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1 vote
2 answers
622 views

What have I achieved through turning on hyperthreading on an old P4?

I have an old P4 3ghz with 3gb of ram. Ive rebuilt it with Windows Server 2008 to act as my test and continuous integration machine. When I went into the BIOS to make it boot from the DVD to install ...
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7 votes
3 answers
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taskset core numbers question

I have quad core CPU with hyper threading enabled. So I have 8 logical cores. I want to limit my application to use only 4 cores and I want this 4 cores to be different physical cores. Which taskset ...
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35 votes
12 answers
68k views

Disable hyperthreading from within Linux (no access to BIOS)

I have a system running a financial trading application at a remote facility. I do not have access to the ILO/DRAC, but need to disable hyperthreading. The system runs Intel Westmere 3.33GHz X5680 hex-...
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5 votes
2 answers
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Is it possible to tell which cpus are hyperthreads of the same core?

I have a server that is a quad-core i-7 with hyperthreading enabled. The kernel recognises this as 8 cpus, as it should. I want to create a couple virtual hosts running on this machine. virt-manager ...
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3 votes
1 answer
3k views

Hyperthreading vs. SQL Server & PostgreSQL

I have read that hyperthreading is a "performance killer" when it comes to DBs. However, what I read didn't state which CPUs. Further, it mostly indicated that I/O was "cut to < 10% performance". ...
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  • 155
28 votes
8 answers
38k views

Will disabling hyperthreading improve performance on our SQL Server install

Related to: Current wisdom on SQL Server and Hyperthreading Recently we upgraded our Windows 2008 R2 database server from an X5470 to a X5560. The theory is both CPUs have very similar performance, ...
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0 votes
1 answer
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Ubuntu 10.04 & Intel Hyperthreading

Does Ubuntu 10.04 allow the use of hyperthreading with the new Intel i7 processor?
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2 votes
2 answers
1k views

Running a VM on a hyperthreaded CPU

Is it better to run a VM on a dual core hyperthreaded machine as a four core or as a two core VM. The hyperthreaded 'virtual' cores are not as fast as the real cores. Does this effect the VM?
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  • 147
2 votes
2 answers
821 views

Hyper-V processors

I'm running a HP ProLiant DL380G6 with 2x Intel® Xeon® E5520 Quad Core Processor 2.26 GHz and 12GB of ram. I got Hyper-V installed and 3 VMs for now. If I open up task manager I can see 16 cores (I'm ...
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