On Mon, Jul 11, 2016 at 12:53:54PM -0400, [email protected] wrote: > Currently irq time accounting only works in these cases: > 1) purely ticke based accounting > 2) nohz_full accounting, but only on housekeeping & nohz_full CPUs > 3) architectures with native vtime accounting > > On nohz_idle CPUs, which are probably the majority nowadays, > irq time accounting is currently broken. This leads to systems > reporting a dramatically lower amount of irq & softirq time than > is actually spent handling them, with all the time spent while the > system is in the idle task being accounted as idle. > > This patch set seems to bring the amount of irq time reported by > top (and /proc/stat) roughly in line with that measured when I do > a "perf record -g -a" run to see what is using all that time. > > The amount of irq time used, especially softirq, is shockingly high, > to the point of me thinking this patch set may be wrong, but the > numbers seem to match what perf is giving me... > > These patches apply on top of Wanpeng Li's steal time patches. > > CONFIG_IRQ_TIME_ACCOUNTING is now a config option that is available > as a separate choice from tick based / nohz_idle / nohz_full mode, > a suggested by Frederic Weisbecker. > > Next up: look at the things that are using CPU time on an otherwise > idle system, and see if I can make those a little faster :) > > v2: address Peterz's concerns, some more cleanups > v3: rewrite the code along Frederic's suggestions, now cputime_t > is used everywhere > v4: greatly simplify the local_irq_save/restore optimisation, thanks > to Paolo pointing out irqs are already blocked by the callers >
Thanks Rick! I'm applying the series with my patches and will do a pull request to Ingo.
