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wa (waiting time) from top command is big


My top command shows me sometimes a big (80-90% or more) wa indicator. So this means my processor waits a LOT for I/O operations.
I/O operations mean writting and reading from hard disk ?

How can I see in realtime a list with processes / commands that make that waiting time so big ?

I mean I want to get a list with the processes that write to hard disk the most in that moment (measured in kbytes/s or whatever). So I can now what to kill / modify for that waiting time to cool.

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1 Solution
Processes in waiting state are denoted as 'D' state, they shown in top or ps output.
Since I/O operations flies through pageCache, You can't identify process's writing speed.
You can attach to such process with debugger and count every read/write syscall, but then, You will count all I/O, not hdd only.
BTW: check for swap usage, maybe You short at RAM?
vmstat 1 # si, so columns
softexp23Author Commented:

The LinuxQuestions.org guys offered me this response:

You'll need a (very) recent kernel with TASKSTATS - there is also a iotop.py out there if you want to have a quick search.

That's what I needed.

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