I'm doing CPU utilization monitoring on a Ubuntu server using statistics provided by /proc/stat. I want to figure out how much time do the CPUs take to process packets under high network load. However, I find that the 6th value in each CPU line in /proc/stat which indicates the interrupts serving time is always 0:
cpu0 1872 0 4205 13586753 1766 0 4169 0 0 0cpu1 13488 0 11840 13569187 1490 0 304 0 0 0cpu2 1676 0 3736 13591826 1323 0 125 0 0 0cpu3 10057 0 9754 13576168 1412 0 23 0 0 0cpu4 5692 0 4912 13586364 1148 0 104 0 0 0cpu5 5754 0 9649 13580709 1232 0 78 0 0 0cpu6 7077 0 5322 13584883 886 0 50 0 0 0cpu7 5802 0 9200 13580866 1401 0 13 0 0 0cpu8 2404 0 5010 13589797 907 0 2 0 0 0cpu9 5602 0 9240 13581843 1075 0 13 0 0 0cpu10 3989 0 4994 13589180 836 0 2 0 0 0cpu11 5711 0 9141 13581729 828 0 17 0 0 0cpu12 2665 0 5416 13590125 885 0 0 0 0 0cpu13 6218 0 8822 13581970 812 0 13 0 0 0cpu14 2510 0 5110 13590959 508 0 2 0 0 0cpu15 6906 0 9112 13580366 1267 0 15 0 0 0cpu16 2651 0 5302 13590403 742 0 22 0 0 0cpu17 7508 0 10270 13578055 937 0 12 0 0 0cpu18 2844 0 5026 13590418 840 0 7 0 0 0cpu19 5582 0 9303 13581885 1123 0 20 0 0 0cpu20 5942 0 5202 13586423 704 0 20 0 0 0cpu21 5208 0 9202 13582565 848 0 14 0 0 0cpu22 6103 0 5226 13587281 659 0 4 0 0 0cpu23 9404 0 11498 13566613 745 0 892 0 0 0I know the intr line in /proc/stat shows the counts for each interrupt, but I want to know the CPU processing time for interrupts instead of how many times that interrupts are triggered. My questions are:
- Why is the interrupt serving time 0?
- Do I have other ways to get CPU processing time for interrupts?
Here is some information about my server.
Kernel version: 4.15.0-43-generic
NIC: Ethernet controller: Broadcom Inc. and subsidiaries NetXtreme BCM5720 Gigabit Ethernet PCIe