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Re: qcow2 perfomance: read-only IO on the guest generates high write IO
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From: |
Steve Litt |
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Subject: |
Re: qcow2 perfomance: read-only IO on the guest generates high write IO on the host |
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Date: |
Thu, 9 Sep 2021 13:34:37 -0400 |
Christopher Pereira said on Thu, 09 Sep 2021 11:48:06 +0200
>Hi,
>
>I'm *reading* a directory with 5.000.000 files (2,4 GB) inside a guest
>using "find | grep -c".
>
>On the host, virt-top reports high *write* IO (40 MB/s !) during over
>1 hour.
My very first step would be to make sure every mount on the guest has
the noatime property, and the mount containing the qemu image you're
working with is mounted noatime.
SteveT
Steve Litt
Spring 2021 featured book: Troubleshooting Techniques of the Successful
Technologist http://www.troubleshooters.com/techniques