CPU is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer.

learn more… | top users | synonyms

29
votes
9answers
15k views

Does CPU power management affect server performance?

I was doing some simple hand benchmarking on our (live) database server during non-peak hours, and I noticed that queries returned somewhat erratic benchmark results. I had enabled the "Balanced" ...
25
votes
2answers
6k views

Disable CPU Scaling in Windows Server 2008 R2

How do you disable CPU power management scaling in Windows Server 2008 R2? After setting the Control Panel, Power Management plan to performance and then rebooting -- CPUID's Cpu-Z still shows the ...
16
votes
3answers
366 views

“Peaky” CPU Usage on Domain Controllers

We have two Windows Server 2008 SP2 (sadly not 2008 R2) Domain Controllers in a small 150 client domain that are exhibiting very "peaky" CPU usage. The Domain Controllers both exhibit the same ...
16
votes
2answers
14k views

Monitoring/controlling Intel Turbo Boost in Linux

Is there a nice way to monitor and/or control Intel Turbo Boost technology on Nehalem processors from a Linux host? I'm looking to do this RHEL/CentOS 5.5 hosts running stock or Realtime MRG kernels. ...
14
votes
6answers
2k views

Do Dual CPUs Provide Fault Tolerance?

Let's say I bought two Intel Xeon's and installed them into server class hardware... If one CPU failed would the other still function and pick up the slack, therefore providing fault tolerance? This ...
12
votes
3answers
2k views

Balancing RAM when using multiple CPUs

We have HP DL360 G7 server with one cpu and 16G 12G ram. We plan to add another cpu. So, we need also ram for second cpu. Is there any negative performance impact if we add different size of ram to ...
12
votes
3answers
2k views

Hyper-V Processor Limitations

We have recently purchased a server which is running Hyper-V 2008 R2 bare metal. The server has two quad-core Intel Xeon processors with hyperthreading, so if I'm understanding correctly this gives us ...
11
votes
5answers
2k views

So really, what is the overhead of virtualization and when should I be concerned?

I'm searching for good rules of thumb to understand when NOT to virtualize a machine. For example, I know that a fully CPU-bound process with near 100% utilization is probably not a good idea to ...
11
votes
10answers
5k views

What creates CPU I/O wait but no disk operations?

I have CPU I/O wait steady around 50%, but when I run iostat 1 it shows little to no disk activity. What causes wait without iops? NOTE: There no NFS or FUSE filesystems here, but it is using Xen ...
11
votes
4answers
17k views

KVM: Which CPU features make VMs run better?

We are using Ubuntu 12.04 with the following parameters: Dell R910 Kernel 3.2.0-25-generic #40-Ubuntu SMP x86_64 x86_64 x86_64 GNU/Linux kvm 1:84+dfsg-0ubuntu16+1.0+noroms+0ubuntu13 qemu-kvm ...
11
votes
3answers
34k views

How to fix “BUG: soft lockup - CPU#0 stuck for 17163091968s”?

UPDATE: I updated the title of the message, because I've recently seen more of these problems with this exact time amount of 17163091968s. This should help people investigating the symptoms to find ...
10
votes
5answers
5k views

Confused by CPU values in Unix 'top' command

In the screenshot below, the overall CPU is being reported as 3% but the mysqld process is reported as using 57%. Is this 57% of the overall 3% and thus mysqld is only using about 1.5% of the CPU? ...
9
votes
6answers
5k views

How do I log CPU usage per process?

I have a box on Linode that's going through weird behavior. Every now and then CPU and disk I/O will shoot to 100% and the server becomes unresponsive and has to be booted. I'd like to investigate ...
9
votes
4answers
27k views

Getting CPU information from command line in Mac OS X [server]

Sometimes I need to gather information about the client's server prior to making real work there, i.e. getting info on CPU type and activity. On Linux there is mpstat and /proc/cpuinfo, both of them ...
8
votes
4answers
2k views

How can I troubleshoot high Kernel time?

I have unusually high Kernel time on my CPUs as shown in task manager. What are some ways I can troubleshoot this?
8
votes
2answers
11k views

Disable CPU cores in bios?

Is it possible to disable CPU (Intel) cores in BIOS, and if yes what HP/DELL (others?) 1U/2U servers would allow this? It is becoming difficult to find new server hardware with dual core CPUs, most ...
8
votes
8answers
3k views

How to correctly apply thermal compound to the CPU?

Every now and then I have to work with hardware, be it assembling a new box, or just cleaning it a little bit, and I always have this question: how should I apply the thermal compound to the CPU? When ...
7
votes
2answers
790 views

How is CPU processing speed reported in /proc/cpuinfo?

$ cat /proc/cpuinfo | grep -iE "model name|cpu MHz|processor" processor : 0 model name : Intel(R) Core(TM)2 Quad CPU Q6600 @ 2.40GHz cpu MHz : 1600.000 processor : 1 model name : ...
7
votes
2answers
5k views

Ubuntu load average spikes but CPUs are idle

We have a server on a cloud network, provided by a third party. We are running Ubuntu 10.04 Server Edition. The problem happens at seemingly random times, around one to three times a day. The load ...
7
votes
2answers
1k views

Server CPU's: How much does L3 cache size matter when it comes to virtualization?

Performance-wise, how much does the L3 cache size on Intel Xeon i7 processors matter for virtualization functions? I'm picking out a Xeon 1366 Nehalem/Westmere CPU for a server I'm spec'ing to be a ...
7
votes
3answers
348 views

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 ...
6
votes
9answers
3k views

Can a Multi core CPU be configured to allow the OS to the see the cores as a single CPU

Can a Multi core CPU server be configured to allow the OS to see all the cores as a single CPU and there by allowing the processor to function as a single CPU? A lot of modern day servers are ...
6
votes
5answers
2k views

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 ...
6
votes
4answers
787 views

using i7 “gamer” cpu in a HPC cluster

I'm running WRF weather model. That's a ram intensive, highly parallel application. I need to build a HPC cluster for that. I use 10GB infiniband interconnect. WRF doesn't depends of core count, but ...
6
votes
8answers
15k views

Get a history of CPU/memory usage

Is there someway to record Task Managers info about CPU and memory usage to examine later? Or an equivalent tool?
6
votes
3answers
2k views

Monitor system CPU / system calls in Linux

I have a couple processes that are eating up a lot of system CPU time (as determined by looking at vmstat). Is there an easy way to find out what kind of system calls are being made? I know there ...
6
votes
6answers
452 views

Life span of Pentium computers

I was given the task to determine the life span of a computer with a Pentium 1 processor. One of our clients is unwilling to upgrade their computers in order for our software to run and we are ...
6
votes
3answers
2k views

Output of /proc/cpuinfo, 2 entries for each core?

Please help me understand the output of /proc/cpuinfo. My new server has dual quad cores. /proc/cpuinfo has two entries for each core (a total of 16 entries): processor : 9 vendor_id : ...
6
votes
2answers
5k views

Is it possible to limit a Linux process so that it can only run on a particular core on a particular machine?

Let's say I have a quad-core box and four identical processes, each with ten threads. Is it possible, in Linux, to say that Process A is only allowed to run on CPU 0, Process B is only allowed to run ...
6
votes
1answer
815 views

KVM/Qemu, Ubuntu: Why do more guests CPUs enhance Disk-I/O rapidly?

We have an Heartbeat/DRBD/Pacemaker/KVM/Qemu/libvirt cluster consisting of two nodes. Each node runs Ubuntu 12.04 64 Bit with the following packages/versions: Kernel 3.2.0-32-generic #51-Ubuntu SMP ...
6
votes
2answers
6k views

Number of logical processors per VM?

I have a server (quad core) running Windows Hyper-V Server 2008 R2 with two Windows Server 208 R2 Standard guest virtual machines. I've noticed the number of logical processors setting (under the ...
6
votes
2answers
2k views

100% CPU load on Ubuntu 10.04.3 LTS 64bit

I have trying to fix this issue for two days with no success. The server is a MySQL database server. Hardware: DELL Poweredge 1950, 2x Intel Xeon Quad Core E5345 @ 2.33GHz, 16 Gb mem, 2x 146Gb SAS ...
5
votes
6answers
5k views

Monitoring CPU usage in Ubuntu

How to find out what process is using CPU to what extent in Ubuntu? I'd like to have real-time data as well as recorded history. Both console and GUI apps would be great. The situation is that my ...
5
votes
4answers
788 views

Which CPU configuration for new servers (IIS7 / Windows Server 2008)?

I have a certain budget for ordering a couple of new servers from a vendor. The new servers will run Windows Server 2008/IIS 7 with a lot of web sites (ASP.NET and classic ASP). They don't have to ...
5
votes
3answers
2k views

Cacti Graphing incorrect load averages

I've just set up cacti to monitor CPU and memory usage on a server that I think needs to be upgraded, but to be able to make my case for funding I need hard facts. I figured getting Cacti to monitor ...
5
votes
3answers
8k views

What does it mean if iostat shows 100% busy wait but the CPU is completely idle?

What does it mean if iostat shows 100% busy wait but the CPU is completely idle? My application runs for a while, then goes into this state periodically for about 10-20 seconds. It is transaction ...
5
votes
5answers
945 views

Ubuntu Server 12.04 CPU Load

I have a Server (2x Hexa-Core Xeon E5649 2.53GHz w/HT with 32GB RAM and 20000 GB Bandwidth) running Ubuntu Server 12.04 LTS. The server runs LAMP and serves one website only, the estimated number of ...
5
votes
3answers
186 views

How to compare CPUs?

What are the metrics and their priorities to compare task specific performance of various CPUs?
5
votes
1answer
132 views

How to verify power provided to processors is clean

Once in a blue moon, I am seeing a blue screen of death on a shiny new Dell R7610 with a single 1100 Watt Dell-provided power supply on a beefy UPS. BCode is 101 (A clock interrupt was not ...
5
votes
2answers
1k views

kvm and qemu host: Is there a limit for max CPUs (Ubuntu 10.04)?

Today we encountered a really strange behaviour on two identical kvm and qemu hosts (Dell R910). The host systems each have 4 x 10 Cores, which means that 40 physical cores are displayed as 80 within ...
5
votes
2answers
273 views

vCenter Cluster CPU utilisation data inaccurate

We have quite a reasonably sized vSphere 'estate', with 80% of our Windows/Linux servers virtualised, running across six Datacentres. One of my challenges is medium to long term capacity planning, ...
4
votes
5answers
444 views

is there anyway to know if your supposedly fully dedicated server is really a virtually resource-shared machine? [duplicate]

sometimes I feel my server not responding as smoothly as I would expect (i have a Intel(R) Xeon(TM) CPU 2.80GHz Quad Core), given that for example, the 'top' commands reports a low load < 0.5, CPU ...
4
votes
7answers
4k views

High CPU load but top processes in top all around 0%

We have a server with unusual high load and cpu util, but we can't figure out why. When we run top all the procs seem to be very low cpu. http://cl.ly/2d1g0K3q261r0R0K3e35 Is there a better way to ...
4
votes
5answers
12k views

How to determine max CPU speed of a processor in Linux?

I have a few 2.6 Linux boxes, running mostly RHEL and SUSE. I know for certain the RHEL machines have power saving on via the cpu governor. When the ondemand governor kicks, /proc/cpuinfo is showing ...
4
votes
4answers
8k views

Virtualized CPU cores vs. threads

We've got a KVM host system on Ubuntu 9.10 with a newer Quad-core Xeon CPU with hyperthreading. As detailed on Intel's product page, the processor has 4 cores but 8 threads. /proc/cpuinfo and htop ...
4
votes
5answers
2k views

How much CPU use is too much?

I've got a server that receives around a million unique visitors a month and I've recently began using Plesk to help monitor some of the vitals on the box itself. RAM I can make sense of, but I'm not ...
4
votes
3answers
5k views

What is the meaning of “deassert” in this context?

The English majors over at Dell provided me with this error message provided by a PowerEdge 2950. CPU2 Status: Processor sensors for CPU2, IERR was deasserted I've Googled it, random forum posts ...
4
votes
2answers
663 views

Why does a CP command on linux consume CPU?

I just run a copy command for two large directories with a small number of huge files and I see my cp process is consuming around half a core in top: 51116 root 20 0 110m 876 688 D 43.9 ...
4
votes
2answers
1k views

Xen - Make one guest OS have 2 cpus?

I have inherited a Xen setup. The dom0 and domU's are all linux. dom0 has 8 cores (or CPUs, I'm not sure). We want to run more stuff on one domU. I want to make it a multicore CPU, ie so that the domU ...
4
votes
3answers
7k views

What is “Interrupts” process and why it so loves my CPU?

I have windows XP SP3 on Intel Core Duo 2GHz. The "Interrupts" process, according to the Process Explorer, continuously take 30-40% CPU. Is it normal?