Questions tagged [smp]

Symmetric multiprocessing (SMP)

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How to calculate the QuickPath Interconnect (QPI) bandwidth?

For Xeon E5-2697 v2, Intel lists: Bus Speed = 8 GT/s # of QPI Links = 2 According to Wikipedia, one must know the QPI frequency and link width to calculate the QPI bandwidth, but these don't seem to ...
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How can I override IRQ affinity for NVME devices

I am trying to move all interrupts over to cores 0-3 to keep the rest of my cores free for high speed, low latency virtualization. I wrote a quick script to set IRQ affinity to 0-3: #!/bin/bash while ...
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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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What will happen if a CPU burst up to 100% utilization in an SMP infrastructure?

I have a web server that has 4 CPUs, It has somehow encountered packet loss intermittently. Finally we moved allthe application and data to another system that has 8 CPUs. We did this because we found ...
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Is a machine with a single NUMA node, actually a regular (non-NUMA) system?

First, let's check I got the fundamentals right: As I understand it, NUMA systems are a (asymmetric) network of NUMA nodes, where a NUMA node is usually (but not always) a physical CPU package. In a ...
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NUMA processor definition

NUMA, non-uniform memory access designates a symetric multi-processing system where processors are grouped into nodes, with each group sharing some level of memory, so that memory access on same node ...
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Server crashes because of SMP

My web server is crashing every few days unless I disable SMP with "nosmp" parameter in Grub config. It is not an hardware failure because the problem persists after moving everything to a new machine....
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SMP kernel sees only one CPU (i7-930) with ACPI enabled

A Gentoo box running a up-to-date SMP kernel sees only one CPU eventhough ACPI is enabled in AmiBIOS. Any ideas why? > uname -a Linux charlie 3.17.7-gentoo #1 SMP Mon Jan 12 19:31:07 CET 2015 ...
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Host CPU use optimization on KVM

I've done KVM based virtualization setup with following configuration. HOST Machine ---------------- OS: CentOS 6.6 (64-bit) CPU: Intel(R) Xeon(R) CPU E5606 @ 2.13GHz RAM: 32 GBs Disk: 2 TBs (LVM-...
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Setting default_smp_affinity on Linux to the correct value

I have 12 core boxes: egrep -c processor /proc/cpuinfo 12 cat /proc/irq/default_smp_affinity fff I would like to use all of the cores so my understanding is that the default_smp_affinity should be ...
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Alternative system fans for EOL HP ML150 G6 servers

Background I have an HP ML150 G6 server that HP made 'End Of Life'. I added a second processor to the system but then was unable to get past POST due to a missing system fan. I found a diagram that ...
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Server crash : "unable to handle kernel paging request"

My fresh new Ubuntu webserver randomly crashes with the following error in the syslog. It doesn't respond anymore and I have to do a hard reboot. It happens almost one time a day. Server kernel is : ...
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Enable SMP on Debian i386?

I've been running a couple old HP machines on Debian for a while, and only recently noticed that they were only 'recognizing' and using one processor. cat /proc/cpuinfo only shows output for processor ...
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Linux SMP Kernel Ram Utilization

I have a linux machine with Redhat 32 bit SMP Kernel installed , the ram size of machine is 16 GB and processor architecture is 64 bit. Please clarify my doubts on this setup : Can OS use the 16GB ...
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Execute curl requests in parallel in bash

What is the best way to execute 5 curl requests in parallel from a bash script? I can't run them in serial for performance reasons.
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How to change SMP affinity of an IRQ on Ubuntu PV domU inside Xen XCP?

I'd like to change IRQ SMP affinity for reasons, outlined in this question: CPU0 is swamped with eth1 interrupts But I can't — I see Input/output error when I try to write to /proc/irq/*/smp_affinity....
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linux kernel soft lock nagios

I've had this happen a few times in the past few days, anyone have any idea what might be causing this? Looks related to nagios/smp/memory management. Seems to be recurring every 24hrs or so. This is ...
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If SMP is disabled, does that mean I cannot use multicores? Or multiprocessors?

I've purchased a VPS for the sake of dev work, and had wished to install NetBSD under the Xen DomU guest. Unfortunately it is stated that this will work, however will not support SMP. Does this mean ...
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Is one Xeon core enough to run a general website on my VPS?

I've purchased a VPS for dev work (at Linode) some time ago and am wishing to install NetBSD for the sake of experience, however its current support under the Xen hypervisor does not allow for SMP. I ...
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ESXi performance considerations with VM that requires many CPUs

I will be looking to buy a new server soon, and would like to consolidate servers into one VM server. I will have equivalent infrastructure offset, so this isn't a case of having all my eggs in one ...
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Multiple vCPUs or multiple identical VMs, which is better?

I am looking to upgrade one of our servers, an 8 core server running VMware Server 2. The VMs it runs are mostly web, file, and email servers; specifically, it runs three webservers, 2 email/file ...
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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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VMWare ESXi and IRQ balancing

VMWare ESXi 4.1 Guest: Linux kernel 2.6.32 64bit (tried older as well) In multi-CPU virtual machine all interrupts (eth0,ata_piix) are stuck to the single CPU. When running on the pure hardware, ...
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Why windows process scheduler assign tasks to random CPUs?

I am on dual core C2D processor, Windows 7 (although this behavior is the same in all MS OSes I've seen). When I run any single threaded CPU-intensive task, it does not stick to 1 core, but rather ...
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Does FreeBSD suffer from SMP issues?

This is not a FreeBSD vs [insert favorite linux server distro]. My interest is in knowing the why and how to remedy sch issues if they exist. Primarily, I'm looking to implement a FreeSwitch based ...
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24 Core LAMP Issue

I have a 24 Core Opteron 8435 system with 48GB of RAM. However, the performance is way below that of our 6 Core Intel with 30GB of RAM. I wonder if anyone could this of why? We're running a Drupal ...
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24 Core Server Performance

I have a quad hexacore system based on the Opteron 8345 chips - that's 24 cores in all with 48GB of ram. This box was meant to replace the current six Intel core box which my current LAMP stack runs ...
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Emulate a SMP server with a Linux Cluster?

Is it possible to combine a few machines into a cluster and have it appears as a single server? For example, with such a cluster we can run a 32-thread CPU-bound process on 8 quad-core machines. Are ...
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How to know when the kernel was last compiled?

I have installed a linux distro and I "think" it is vulnerable to kernel exploits. I have to update kernel but I need to know if it is really compiled in year 2003? How can I know if additional ...
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Should a core be "reserved" for the OS in a multi-core (SMP) Linux system?

If I plan to run eight applications on an eight core machine and expect all applications to utilise 100% cpu, will the OS "get enough time" for its own tasks or should I instead run seven applications ...
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How can I tell if irqbalance is doing anything?

I've looked into linux server tuning docs that mention installing irqbalance (http://www.irqbalance.org/) on SMP systems. I'm looking at it now on a quad-core system, and while "ps axf" can tell me ...
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Will multiple processors show in /proc/cpuinfo on a kernel that doesn't have SMP enabled?

I have recently migrated an application from one server to another and am having some issues I am wondering if they are associated to HyperThreading. In regards to my question, I currently don't have ...
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Reclaiming an old server [closed]

I got a server, four-2.6Ghz AMD opteron and 10Gigs RAM on TYAN Thunder board, for free. The thing is massive and loud, I'd like to reclaim the processors and RAM into two smaller computers each with ...
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Why is CPU use so asymmetric on our 8-cpu SQL Server box?

I've noticed that the CPU usage on our 8-CPU database server, running SQL Server 2008, is not balanced at all. Here are the 1 day averages for a random day a while back, which is typical and ...
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3 answers
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Best hardware/software solution for parallel makes?

We've got a Linux-based build system in which a build consists of many different embedded targets (with correspondingly different drivers and featuresets enabled), each one built with another single ...
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How can I emulate more virtual CPU than physically available?

In VMWare you can use multiple CPU, but only as much as present on the host. Is there a way to use more CPU than physically available ? It would be to : test software designed to run on an ...
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