Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757609Ab2JJXsi (ORCPT ); Wed, 10 Oct 2012 19:48:38 -0400 Received: from mail-qc0-f174.google.com ([209.85.216.174]:54468 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751198Ab2JJXsg (ORCPT ); Wed, 10 Oct 2012 19:48:36 -0400 From: Frederic Weisbecker To: "Paul E. McKenney" Cc: LKML , Frederic Weisbecker Subject: [PATCH] rcu: Advise most users not to enable RCU user mode Date: Thu, 11 Oct 2012 01:48:28 +0200 Message-Id: <1349912908-11814-1-git-send-email-fweisbec@gmail.com> X-Mailer: git-send-email 1.7.5.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1583 Lines: 49 Discourage distros from enabling CONFIG_RCU_USER_QS because it brings overhead for no benefits yet. It's not a useful feature on its own until we can fully run an adaptive tickless kernel. Signed-off-by: Frederic Weisbecker --- init/Kconfig | 12 ++++++++++++ 1 files changed, 12 insertions(+), 0 deletions(-) diff --git a/init/Kconfig b/init/Kconfig index c26b8a1..89093e1 100644 --- a/init/Kconfig +++ b/init/Kconfig @@ -451,6 +451,12 @@ config RCU_USER_QS excluded from the global RCU state machine and thus doesn't to keep the timer tick on for RCU. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_USER_QS_FORCE bool "Force userspace extended QS by default" depends on RCU_USER_QS @@ -459,6 +465,12 @@ config RCU_USER_QS_FORCE test this feature that treats userspace as an extended quiescent state until we have a real user like a full adaptive nohz option. + Unless you want to hack and help the development of the full + tickless feature, you shouldn't enable this option. It adds + unnecessary overhead. + + If unsure say N + config RCU_FANOUT int "Tree-based hierarchical RCU fanout value" range 2 64 if 64BIT -- 1.7.5.4 -- 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/