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Questions tagged [hyperthreading]

In a hyperthreaded CPU, for each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible.

In an hyper threaded environment, For each processor core that is physically present, the operating system addresses two virtual or logical cores, and shares the workload between them when possible.

This allows to decrease the number of dependent instructions on the pipeline. It takes advantage of superscalar architecture (multiple instructions operating on separate data in parallel).

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Cluster Configuration - Worker Nodes

I am beginner in cluster configuration. I know in our cluster we have types of worker nodes: 16 x 4TB Disks 128 RAM 2 x 8 Core CPUs 12 x 1.2 TB Disks 256 RAM 2 x 10 Core CPUs I am confused about the configuration. What does mean 2 x 8 cores? It…
p.magalhaes
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Parallel.Foreach considers logical cores or physical cores where hyperthreading supported?

I have been using Parallel.ForEach to fetch & process data concurrently. Collection which is used in Parallel.ForEach has more than 100 elements. If i don't restrict number of thread created in parallel then creating SqlConnection out of Connection…
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hyperthreading - which thread runs when both threads are ready

The idea behind Intels hyperthreading is (as far as I understand) that one core is used for two threads in a time-multiplexed manner. The HW support this by having the state-related resources doubled and time-sharing other resources. If the running…
Support Ukraine
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Hyper-v number of Virtual CPU on Virtual Machine

VMware world recommends that you only add one Virtual CPU on each Virtual Machine unless that your application requires detect more than one CPU. Does this recommendation applies on Microsoft Hyper-V world? or if I requires more CPU power on a…
Uh Trog
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each of 3 ALU+decoders walk on 3 different conditional branches on `switch`/`case` simultaneously?

As known, on Intel x86_64 the Hyper Threading allow to use shared execution units (ALUs, ...) from different threads simultaneously - this is known as Simultaneous multithreading (SMT). And known, that threads, which executed on Hyper Threading…
Alex
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What does 128 threads per processor mean for a supercomputer?

This article about YARC mentions that the super computer has 128 threads per processor. Is the same thing concept as hyperthreading, where essentially the cpu has additional registers that allows to act as multiple processors?
dwjohnston
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Hyperthreading effects on gettimeofday and other time measurements

while I was benchmarking a CPU with hyperthreading with BLAS matrix operations in C, I observed a nearly exact doubling of the runtime of the functions when using hyperthreading. What I expected was some kind of speed improvement because of out of…
bknux
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Can multiple processes hide latency of SSE instructions?

I'm in need of high-performance merging and came accross: Efficient Implementation of Sorting on Multi-Core SIMD CPU Architecture by Jatin Chhugani et al. Their aim is to get the most performance out of 1 CPU, one part of their solution is to use a…
hbogert
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How does one specify physical CPU ids in openmpi 1.6.4+ rankfiles?

The latest (v1.8.3) OpenMPI documentation specifies that rankfiles must now use the logical cpu IDs reported by hwloc rather than the physical IDs, see the last sentence in the Rankfiles section of the mpirun documentation here: Starting with Open…
Squirrel
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Hyperthreading - realy X2 cores?

According to Intel (If I'm not wrong) the Hyper threading (HT) can: - up the performances up to 30%. - HT can make better use the CPU when there is one task which use the ALU unit and the other doing I/O (for example: one task use zip alg and the…
user3668129
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Hyper-threading and gaming (and other computing applications)?

I was wondering what the real-world performance effects are of hyperthreading (multiple logical cores for each physical core) in different situations. Intel advertises this as being effective for when threads of execution are waiting for I/O,…
Reed B
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Find out the defualt pthread affinity policy followed by a Linux Kernel 2.6.32

I am trying to find out what is the default affinity policy followed by a Scientific Linux Kernel 2.6.32 when creating pthreads in a HT system. Is there a way of knowing it? In the pthreads creation there are no calls to affinity, so I guess the…
Manolete
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Django + Uwsgi + CPU Hyperthread would this have advantage on parallelism?

Lets say I have a django project running on uwsgi emperor mode, with this config processes = 4 Running on a dual core cpu with hyperthreading enabled, does that mean I can have [close to] true parallelism of processing 4 requests at the same…
James Lin
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Virtualization of Hyper-threaded cores

I'm looking for some guidance before I spend tons of time reorganizing a legacy program. If I have cores that are part of a virtual cluster. I have a computation that is broken into many parts and distributed to each member of the cluster. If each…
user3076878
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Why does hyper-threading benefit my algorithm?

I have a dual core machine with 4 logical processors thanks to hyper-threading. I am executing a SHA1 pre-image brute force test in C#. In each thread I basically have a for loop and compute a SHA1 hash and then compare the hash to what I am looking…
Eiver
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