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Questions tagged [iowait]

Iowait is the time a CPU is in an idle state, waiting for IO-operations to complete.

In UNIX/Linux systems, is the amount of time or percentage of time, in which the CPU is idle and waits for completion of IO-operations. This state of the CPU can be seen in the output of the top-command under wa.

To test the behavior of this value (to produce iowait-time),e.g. the dd-command can be used:

dd if=/dev/sda of=/dev/null

Note that if there is an other process that is using the same CPU as this command, it is possible that the other process is using this CPU and the CPU won't be in idle state nor in iowait-state.

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Is there a tool on Ubuntu or Mac to monitor a program's CPU and I/O usage and I/O wait times?

I want to determine if my application is IO or CPU bounded. Is there such a tool to determine how much of your application's run time is spent on CPU wait/IO wait/running on CPU etc.? I am running my application from terminal. I have heard there is…
burhan
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Nginx constant writes causes CPU I/O wait

I'm running nginx/1.20.1 on a G9 CentOS 7 machine for serving static video files with the following specs: 32 cores of CPU 32GB of RAM 6TB of HDD storage Nginx config: user root; worker_processes auto; error_log /var/log/nginx/error.log; pid…
Erfun
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Any way to log the live data of (top, iotop, iostat) outputs on daily basis

Recently I face an issue in my java application that is running in jboss eap 7. All the process that are forked by my java application is hung and it's not running. When I debugged further, I found that the cpu is utilised completed by some process…
GouthamRio
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Is Postgres Autovacuum causing a read query to stuck at IOWait wait event?

I have encountered several occasions where my read query is stuck for hours and when checked on pg_stat_activity it has wait_event_type of IOWait. It also happens that every time this happens, there is an active autovacuum running on that table. The…
yonasstephen
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ignite write big data in a pressure test, io write and read time tow high?

I hava some write and find in ignite with sql.When I have a pressure test with 100 persons, ignite server's cpu is low, but iowait is two heigh, and io write and read time is two heigh. So I have some ways to reduce iowait? I use 2.7.6 version with…
zhangzl
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Error on RabbitMQ "wal: encountered error during recovery: badarg"

I'm using RMQ high available cluster with 3 nodes, version : 3.8.3 Spec : RAM : 4GB CPU : 2CPUs Intermittently I'm getting following errors and some nodes are crashed with memory alarms. Application mnesia exited with reason: stopped wal:…
Madura Dissanayake
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Why iowait of reading file is zero?

After finding the psutil, I had a simple experiment. There is a completely IO base function that repeatedly reads some numpy array from files (each of them has 763M size). Then, time usage of the function is measured using "cpu_times" after 100…
Ehsan
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cassandra read high iowait

data read per second I have a three node cassandra cluster。when I have multi thread querying from the cluster ,the io load is very high.The cluster holds about 80GB data per node.I use time window compact strategy and time-window is ten hour.One…
roger.han
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iowait kills performance on Android

This is on Android, my application slows down the UI interaction when it is trying to create a big file, my SD card is slow and I can observe that high iowait occurs and the CPU just sits idle when creating the big file, during this process, the…
neevek
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Oracle 11g high IO Wait

Oracle Version: 11.1.0.7.0 We are having higher IO Wait in one of our Oracle RAC instance One SQL is having high elapsedtime by execution - 1452.57s per execution. This started happening suddenly one day. Previously, it was taking max 3-4 min to…
Rajeev
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Differentiating IOWAIT in Linux

I'm working on a monitoring agent that works with systems using the Linux kernel. By opening /proc/stat , you can easily tell how much time one one or all CPUs (aggregate) is burning waiting for I/O requests to complete. I'm trying to find a way to…
Tim Post
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