Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753211AbaFDLlL (ORCPT ); Wed, 4 Jun 2014 07:41:11 -0400 Received: from mail-oa0-f46.google.com ([209.85.219.46]:38632 "EHLO mail-oa0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752513AbaFDLlJ (ORCPT ); Wed, 4 Jun 2014 07:41:09 -0400 MIME-Version: 1.0 Date: Wed, 4 Jun 2014 17:11:08 +0530 Message-ID: Subject: [Query] Can we use normal timers (kernel/timer.c) while in NO_HZ_FULL mode? From: Viresh Kumar To: =?UTF-8?B?RnLDqWTDqXJpYyBXZWlzYmVja2Vy?= , Thomas Gleixner Cc: Kevin Hilman , Daniel Lezcano , Lists linaro-kernel , Linux Kernel Mailing List , Linaro Networking , Preeti U Murthy Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, While working on the ONESHOT_STOPPED mode I came across another confusing scenario.. Normal timers (kernel/timer.c) don't configure clockevent devices at all but they always rely on PERIODIC tick interrupts to get them scheduled. i.e. normal timers would be only serviced at next tick interrupt (in both LOW & HIGH resolution modes).. Suppose we have entered into NO_HZ_FULL mode (we made sure that there are no normal timers queued) and a normal timer was added after that. We will add it to the timer list but as there is no tick-sched timer, we wouldn't be able to service the normal timer until next time tick fires again (MAX 1 second currently).. And once we remove this MAX 1 second limitation, we might not service this normal timer for long.. Does this problem statement make sense? Or we don't have any such problem? -- viresh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/