show summary of image sizes at end of tests

[jodh-intel]

It would be useful to see a formatted list of the images and initrds at the end of the test, showing the sizes of each.

[marcov]

Currently images size is set to always be 512MB:

osbuilder/Makefile

Line 13 in 93ad049

IMG_SIZE=500

osbuilder/image-builder/image_builder.sh

Line 186 in 93ad049

qemu-img create -q -f raw "${IMAGE}" "${IMG_SIZE}M"

[jodh-intel]

Hi @marcov - actually, that's just a starting size - note that create_rootfs_disk() is called recursively! :-)

See also: #30.

[grahamwhaley]

iirc, we do still round up to a nice boundary though on the actual .img file size. What we really want to see is more like a 'df' of what is inside the image (so we could loop mount and have a peek maybe), or really really something like a PSS measure running a single docker busybox sh or something like the memory consumed in the container test. What I think we are really interested in is the runtime impact on both the host and guest.

[marcov]

@grahamwhaley: how is PSS affected by the rootfs size? Is it because we cache in memory the guest filesystem?

[grahamwhaley]

@marcov tbh, I'm not sure it is. It might be that QEMU has to cache more or construct more (larger) structures to do the mappings etc. It is probably more likely that the costs on the host side will be in the host side kernel (page tables etc.) maybe, which we'd see with the system level density test. But, that test is probably not going to give a stable result when running a single container.