top is a Unix/Linux/BSD program to show what processing are running. It can show the top users of CPU or memory.

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Is my centOS dedicated server caching disk files appropriately, or not?

Here's the head of the top output from my centOS 5 server, at a moment with very low load. What I want to know is whether it is using its free memory wisely to cache files from disk. Of 2G of RAM, ...
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Why one process is taking so many resources

My website is being very slow or non-responsive. A quick look at the top command shows me something like this: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1709 mysql 20 ...
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is CPU actually occupied during iowait (%wa in top) on Linux / EC2?

On an 8-way Amazon EC2 instance (running Linux 2.6.21) with 8 EBS volumes and a lot of disk traffic, we see high %wa in top (30-40%), and high load average (8-9). My understanding is that processes ...
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What could be causing load spikes on this EC2 instance?

I have an Amazon EC2 instance (c1.medium, ami-ed46a784) that experiences short spikes in load average every 32 hours or so. The average load is normally around 0.15 but rises to 3+ for about 15 ...
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Linux memory usage

We've been having some Linux memory usage problems on some of our servers. free, top, ps, and vmstat are all showing 261M free out of 1G (~25%). However, adding up the amount of memory shown per ...
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TOP cpu %ulitization exceeds number of procs X 100%

I have a VM with 2 virtual CPUs. When I run two multi-threaded java proceses the total CPU utilization in top exceeds 200%. In fact its closer to 800%. I thought that %CPU was the percentage ...
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806 views

%CPU for a process

Looking at the output of top on our server, one of my colleagues told me that the fact that some processes got less than 100 "%CPU" was because I was running too many processes. He added that based on ...
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How to understand the memory usage and load average in linux server

I am using a linux server which has 128GB of memory and 24 cores. I use top to see how much it is used. Its output is pasted at the end of the post. Here are two questions: (1) I see that each of the ...
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Running 'top' with 'Irix mode' off in batch mode

Can anyone tell me how I can tweak the following top command so that it always runs in Solaris mode in a batch mode operation? top -d 3 -n 2 -b -p <PID> I need 'top' to output a process' CPU ...
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Linux - How can I see what's waiting for disk IO

I have a server that has a really high load. Nothing is jumping out at me in terms of CPU usage, and it's not swapping. I think it's cause some processes are waiting for disk IO, and I want to see ...
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How is memory usage reported in Linux?

Using ps, I can see the size, the vsize (same as top's VIRT?), and the rss (same as top's RES?). (One more I see in top is SHR.) Could someone summarize for me what these different fields mean?
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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? ...
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how do you interpret output of top?

Some things in top's output are pretty straightforward, like memory and swap usage. But load average numbers are a bit of a mystery: what do these three numbers mean? Also, what exactly is a zombie ...