From mboxrd@z Thu Jan 1 00:00:00 1970 From: fweisbec@gmail.com (Frederic Weisbecker) Date: Thu, 14 Nov 2013 12:53:15 +0100 Subject: a bug on NO_HZ_FULL_ALL In-Reply-To: References: <52843855.5060509@linaro.org> <52847FBE.9070501@linaro.org> <52848547.9080604@linaro.org> Message-ID: <20131114115313.GC16501@localhost.localdomain> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org BTW, support for ARM's full dynticks is uncomplete without "[PATCH] ARM: Support arch_irq_work_raise() via self IPIs" ...which I'm not sure is applied upstream, or even any ARM tree yet. On Thu, Nov 14, 2013 at 05:54:10PM +0800, Shaojie Sun wrote: > No, I think it is a bug. > > Because I tested the option with NO_HZ_FULL and without > NO_HZ_FULL_ALL. It had only little interruptes on CPU0 twd. > With same code, I added NO_HZ_FULL_ALL option. It had too many > interruptes on CPU0 twd. > > So the sumbitter just didn't test twd interrupts, when he expanded > NO_HZ_FULL option to all cpu. > > On Thu, Nov 14, 2013 at 4:09 PM, viresh kumar wrote: > > On Thursday 14 November 2013 01:35 PM, Vincent Guittot wrote: > >> AFAICT, It's a none issue. In full nohz, a timer fires periodically > >> (around 4sec period on ARM IIRC) on one cpu (cpu0). > > > > Timer should always be running on CPU0, its out of nohz-full domain. Its > > cpu 1, where it will fire after long delays.. > > > > > > https://wiki.linaro.org/WorkingGroups/PowerManagement/Doc/AdaptiveTickless