Why I did it
We install many deb packages when building sonic slave images.
To guarantee that the filesystem data is always consistent and safe,
dpkg performs fsync(2)s on its database and files unpacked from packages.
We don't need to use fsync for sonic slave images.
So we can reduce build time using eatmydata.
How I did it
Install deb package eatmydata in sonic-slave-buster and sonic-slave-bullseye docker images.
Pass apt-get install, apt install, apt-get upgrade, and dpkg -i with arguments directly to eatmydata.
How to verify it
Compare the build time of sonic-slave images with and without eatmydata.
For some NVME SSD I improved it by 30-40%.
You get no performance boost if your fs is mounted with options like nobarrier.
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