All writing
~/writing/tags
#linux
3 posts
Systems debugging
10 minWhat is putting those bytes on the wire?
The storage interface on a production cluster was pulling 4 to 12x more than the public interface where client requests arrive. Getting to a defensible number meant distrusting everything, including my own profiler, which was off by 30x.
#ceph#ebpf#linux#kernel
Precision timing
10 minThe frozen clock that nobody noticed
A GPS-disciplined NTP server stopped being disciplined, and every monitor stayed green. The giveaway was a freq_ppb value that repeated byte-for-byte across three seconds, which a live servo never does.
#ptp#ntp#gps#linux
Systems debugging
7 minThe game that rebooted the hypervisor
A friend's gaming VM hard-reset its Proxmox host the instant a game launched, with nothing in the logs. The cause was below every layer we kept editing: a power transient at game launch that tripped a PCIe fault and reset the box.
#proxmox#vfio#gpu#linux