This is 2.6.32, but I think 2.6.36 is the same. Thanks, Fushen On Tue, Dec 13, 2011 at 3:34 PM, Benjamin Herrenschmidt < b...@kernel.crashing.org> wrote:
> On Wed, 2011-12-14 at 00:28 +0100, Thomas Gleixner wrote: > > On Wed, 14 Dec 2011, Benjamin Herrenschmidt wrote: > > > > > 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 ? :-) > > > > Not really, that had been an issue before and had been fixed. Peter ???? > > Fusen, what kernel version is this ? > > Cheers, > Ben. > > >
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