top_blockio

The top_blockio gadget provides a periodic list of input/output block device activity. This gadget requires Linux Kernel Version 6.5+.

Note: If you have an encrpyted disk some block IO operations will not be shown, since device mappers are in between these operations to operate transparently. See https://docs.kernel.org/admin-guide/device-mapper/dm-crypt.html

Getting started

Running the gadget:

kubectl gadget

$ kubectl gadget run ghcr.io/inspektor-gadget/gadget/top_blockio:latest

ig

$ sudo ig run ghcr.io/inspektor-gadget/gadget/top_blockio:latest

Guide

Run a pod / container:

kubectl gadget

$ kubectl run --restart=Never --image=busybox test-top-blockio -- sh -c 'while true; do dd if=/dev/zero of=/tmp/test count=4096; sync; sleep 0.2; done'
pod/test-top-blockio created

ig

$ docker run --name test-top-blockio -d busybox /bin/sh -c 'while true; do dd if=/dev/zero of=/tmp/test count=4096; sync; sleep 0.2; done'
...

Then, run the gadget and see how it shows the sync process:

kubectl gadget

$ kubectl gadget run top_blockio:latest
K8S.NODE            K8S.NAMESPACE       K8S.PODNAME         K8S.CONTAINERNAME          PID MAJOR      MINOR      COMM       BYTES      US        IO        RW 
minikube            default             test-top-blockio    test-top-blockio          8086 8          0          sync       81920      45        1         wr…
minikube            default             test-top-blockio    test-top-blockio          8055 8          0          sync       606208     547       3         wr…
minikube            default             test-top-blockio    test-top-blockio          8082 8          0          sync       65536      95        2         wr…
minikube            default             test-top-blockio    test-top-blockio          8084 8          0          sync       147456     95        2         wr…
...

ig

$ sudo ig run top_blockio:latest -c test-top-blockio
RUNTIME.CONTAINERNAME                                PID MAJOR       MINOR       COMM             BYTES                US                   IO         RW     
test-top-blockio                                   11723 8           0           sync             212992               747                  3          write  
test-top-blockio                                   11727 8           0           sync             65536                75                   1          write  
...

Finally, clean the system:

kubectl gadget

$ kubectl delete pod test-top-blockio

ig

$ docker rm -f test-top-blockio