[Linux] add children_iowait to Process.cpu_times()

[simonmarcin]

Summary

• OS: { Linux }
• Type: { core }

Description

The return values of cpu_times() are inconsistent. When profiling multi-process applications, one loose the iowait values (introduced in 1527). CPU user and system values get automatically added to children_user and children_system. To keep track of the time spent in iowait, one has to manually store the last iowait value of all childs and add it to the parent structure. It would be easier and consistent if psutil would also return a children_iowait value in Process.cpu_times().

[giampaolo]

psutil exposes children_user and children_system because the kernel expose that information. For iowait it does not, so we cannot have iowait_children.