On Linux the accounting stats come from /proc/stat entries and the mapping is:
https://www.kernel.org/doc/html/latest/filesystems/proc.html VIR_NODE_CPU_STATS_KERNEL = (system + irq + softirq) VIR_NODE_CPU_STATS_USER = (user + nice) VIR_NODE_CPU_STATS_IDLE = idle <VIR_NODE_CPU_STATS_INTR> = N/A, irq is accounted by libvirt as KERNEL VIR_NODE_CPU_STATS_IOWAIT = iowait VIR_NODE_CPU_STATS_GUEST = guest VIR_NODE_CPU_STATS_GUEST was introduced in: b5878727c714 ("util: virHostCPUGetStatsLinux: support VIR_NODE_CPU_STATS_GUEST") with the goal of specifically accounting the CPU time spent running guest VCPUs. Unfortunately at the time it was not considered that to get a measure of this time, "guest" is not sufficient, because any guest that is "niced" is accounted in a separate category, "guest_nice". This patch rectifies the situation by adding the guest_nice counter, so that VIR_NODE_CPU_STATS_GUEST = (guest + guest_nice) which makes the statistic useful to the caller, as the totals sum up correctly. In order to find the total USER time spent running host tasks, for example: cpu_user_host = VIR_NODE_CPU_STATS_USER - VIR_NODE_CPU_STATS_GUEST this follows from the fact that "guest" is included in "user" accounting, and "guest_nice" is included in "nice" accounting. Extend the existing tests artificially to capture this specific case. Fixes: b5878727c714d813c820ad4a1b695fbbb5ffc84e Signed-off-by: Claudio Fontana <[email protected]> --- src/util/virhostcpu.c | 2 +- tests/virhostcpudata/linux-cpustat-24cpu.out | 8 ++++---- tests/virhostcpudata/linux-cpustat-24cpu.stat | 4 ++-- 3 files changed, 7 insertions(+), 7 deletions(-) diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c index 1db096ba24..f2b25e940b 100644 --- a/src/util/virhostcpu.c +++ b/src/util/virhostcpu.c @@ -882,7 +882,7 @@ virHostCPUGetStatsLinux(FILE *procstat, return -1; if (virHostCPUStatsAssign(¶ms[4], VIR_NODE_CPU_STATS_GUEST, - guest * TICK_TO_NSEC) < 0) + (guest + guest_nice) * TICK_TO_NSEC) < 0) return -1; return 0; } diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.out b/tests/virhostcpudata/linux-cpustat-24cpu.out index f3183f5c41..a975702a06 100644 --- a/tests/virhostcpudata/linux-cpustat-24cpu.out +++ b/tests/virhostcpudata/linux-cpustat-24cpu.out @@ -1,16 +1,16 @@ cpu: kernel: 8751170 user: 14128079 -idle: 1816344522 +idle: 1816344521 iowait: 81323 -guest: 5880634 +guest: 5880635 cpu0: kernel: 447603 user: 749021 -idle: 75399242 +idle: 75399241 iowait: 5295 -guest: 331814 +guest: 331815 cpu1: kernel: 167215 diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.stat b/tests/virhostcpudata/linux-cpustat-24cpu.stat index bc9d449e1c..e13035b5f0 100644 --- a/tests/virhostcpudata/linux-cpustat-24cpu.stat +++ b/tests/virhostcpudata/linux-cpustat-24cpu.stat @@ -1,5 +1,5 @@ -cpu 14126233 1846 7764352 1816344522 81323 395581 591237 0 5880634 0 -cpu0 748997 24 320851 75399242 5295 22050 104702 0 331814 0 +cpu 14126233 1846 7764352 1816344521 81323 395581 591237 0 5880634 1 +cpu0 748997 24 320851 75399241 5295 22050 104702 0 331814 1 cpu1 337325 1 140909 76178612 1121 8962 17344 0 166726 0 cpu2 666860 29 269302 75649696 4298 18473 21155 0 272094 0 cpu3 328387 77 211400 76131634 1219 9701 6573 0 115551 0 -- 2.35.3
