On Fri, Aug 20, 2021 at 12:40:04PM +0300, Andrey Ryabinin wrote:
cpuacct has 2 different ways of accounting and showing user and system times.
The first one uses cpuacct_account_field() to account times and cpuacct.stat file to expose them. And this one seems to work ok.
The second one is uses cpuacct_charge() function for accounting and set of cpuacct.usage* files to show times. Despite some attempts to fix it in the past it still doesn't work. Sometimes while running KVM guest the cpuacct_charge() accounts most of the guest time as system time. This doesn't match with user&system times shown in cpuacct.stat or proc/<pid>/stat.
Demonstration: # git clone https://github.com/aryabinin/kvmsample # make # mkdir /sys/fs/cgroup/cpuacct/test # echo $$ > /sys/fs/cgroup/cpuacct/test/tasks # ./kvmsample & # for i in {1..5}; do cat /sys/fs/cgroup/cpuacct/test/cpuacct.usage_sys; sleep 1; done 1976535645 2979839428 3979832704 4983603153 5983604157
Thanks for expanding on this, and fixing broken cpuacct_charge.
For the series, Reviewed-by: Daniel Jordan daniel.m.jordan@oracle.com