4 ms·
unless you do something special, a lot of interrupts are handled by CPU 0. there's techniques like Receive-Side Scaling to balance this load across the cores bu
by sterlind 4y ago
unless you do something special, a lot of interrupts are handled by CPU 0. there's techniques like Receive-Side Scaling to balance this load across the cores but that's specific to NICs.
- bayindirh 4y agoHowever, I can pin a VM to far away cores to CPU0 (e.g. socket 3, cores 20-23), hence isolating it from all the interrupt handling, and attack that VM instead, at least in theory, no?
- robocat 4y agoIs that because CPU 0 tends to be scheduled by default? Or is that because the CPU usually uses core CPU 0, and Linux schedules to different cores? Redhat Linux docs[1]: The /proc/interrupts file lists the number of interrupts per CPU per I/O device. It displays the IRQ number, the number of that interrupt handled by each CPU core, the interrupt type, and a comma-delimited list of drivers that are registered to receive that interrupt. The default value for smp_affinity is f, meaning that the IRQ can be serviced on any of the CPUs in the system. To view use cat /proc/irq/32/smp_affinity for interrupt 32 as example. Setting this value to 1, like echo 1 >/proc/irq/32/smp_affinity, means that only CPU 0 can service interrupt 32. [1] https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/6/html/performance_tuning_guide/s-cpu-irq https://access.redhat.com/documentation/en-us/red_hat_enterp...