Post by @yuka@s.umeyashiki.org

@yuka@s.umeyashiki.org

2026-03-11 12:07 UTC

Today I realized that my Linux Contabo VPS has a built-in script in `/etc/cron.hourly` that drops the cache every hour. I found it when I checked dmesg; there are so many "drop_caches: 1" lines. I guess the memory is not dedicated, but shared via KVM memory ballooning. It seems Contabo tries so hard to reclaim physical memory from its customers by dropping page caches every hour. I feel like Contabo is somewhat notorious for aggressive overprovisioning. I will delete the `free` script. #linux #contabo #mm #kvm #vps

Replies (3)

@ammarfaizi2@social.gnuweeb.org 2026-03-12 06:41

@yuka@s.umeyashiki.org Interesting finding! BTW, the KVM ballooning requires the host OS to cooperate with the guest OS. If you can modify your kernel so that it does not cooperate with the hypervisor, then the hypervisor can't steal the memory from you.

Open ##3421623
@yonle@fedinet.waltuh.cyou 2026-03-11 12:17

@yuka@s.umeyashiki.org interesting, but it kinda depends on the customer opinions in the end. On the bright side, you also got big free ram spaces, but on the dark side, it is what it is.

Open ##3577482
@eht16@casual.pending.io 2026-03-11 18:30

@yuka@s.umeyashiki.org Are you really surprised about overcommittent at Contabo? There is probably no other way to offer such low prices. If you want rather fair hosting, you would have to pay fair prices as well. Still, interesting approach to automatically purge page caches automatically on customer systems :smile:.

Open ##3577487