On Tue, 2011-12-13 at 12:42 -0800, Fushen Chen wrote: > On APM82181, "vmstat" (/proc/stat) doesn't show correct idle > percent, if kernel enables "CONFIG_NO_HZ" (Tickless System / Dynamic > Tick). > > When I run wireless throughput test with heavy traffic, "vmstat" shows > very high idle percent while "oprofile" shows very low idle percent. > During the test, the system is idle, but network traffic uses a lot of > hard IRQ and soft-irq time. "vmstat" would have the correct stats if > account_idle_ticks(ticks) in kernel/time/tick-sched.c doesn't add more > idle time in "vmstat". In the same test, if I disable "CONFIG_NO_HZ" > in kernel, idle percent in "vmstat" and "oprofile" would match. > > My APM82181 kernel configuration is "CONFIG_NO_HZ", "CONFIG_HZ_250=y", > "CONFIG_HZ=250", and "CONFIG_HIGH_RES_TIMERS". > > My question is that if kernel enables "CONFIG_NO_HZ", how would kernel > report correct stats.
Hi Thomas ! Any idea what we're doing wrong ? :-) Cheers, Ben. > Thanks, > Fushen > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
