> Therefore, application performance can be impacted if the application > reads /proc/stat rather frequently.
[nods] Text interfaces can be designed in a very stupid way. > For example, reading /proc/stat in a certain 2-socket Skylake server > took about 4.6ms because it had over 5k irqs. Is this top(1)? What is this application doing? If it needs percpu usage stats, then maybe /proc/stat should be converted away from single_open() so that core seq_file code doesn't generate everything at once. > - > - /* sum again ? it could be updated? */ > - for_each_irq_nr(j) > - seq_put_decimal_ull(p, " ", kstat_irqs_usr(j)); > - This is direct userspace breakage. Proper fix is to start strategic switch away from /proc. It is a fun toy but its time has come.
