[PATCH 3/3] perf stat: Use group read for event groups

2017-07-26 Thread Jiri Olsa
Make perf stat use group read if there are groups defined. The group read will get the values for all member of groups within a single syscall instead of calling read syscall for every event. We can see considerable less amount of kernel cycles spent on single group read, than reading each

[PATCH 3/3] perf stat: Use group read for event groups

2017-07-26 Thread Jiri Olsa
Make perf stat use group read if there are groups defined. The group read will get the values for all member of groups within a single syscall instead of calling read syscall for every event. We can see considerable less amount of kernel cycles spent on single group read, than reading each