From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAC9FC433B4 for ; Thu, 22 Apr 2021 12:02:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6B76361461 for ; Thu, 22 Apr 2021 12:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236237AbhDVMCz (ORCPT ); Thu, 22 Apr 2021 08:02:55 -0400 Received: from mail.kernel.org ([198.145.29.99]:56460 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236186AbhDVMCv (ORCPT ); Thu, 22 Apr 2021 08:02:51 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A2FCF613FA; Thu, 22 Apr 2021 12:02:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1619092936; bh=ybvxpwgzpYW4yZF9YvvxKaXAx/OBphRGXXx4PIbqQw4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=uPHDA6dDTiDuGZw6+M2gJKhICMTo2R3iGsdsE3QFumEVu/bqPmLZe2Vu55o2XcwsV BKVHjYe78DyG0joF6Ar/OowNYztd85qrl3CGFSalFaoZ8vXNenSm1L0DxmhPhPDOmE UodNwNYNRMdRzzDUK950Ww1ozWO3dJGeZ4xDNarinGLfJB8ua4tAJHLNe3YE/o/RM0 ctK4RQTjoEQB+nEstCpwlqnLDPhL68PY56QhPKtDXMwikKHfHbaP9L9PhPk7rQLcXC ykx9/hrTE3TLELDQyA/wJaYBGjD3laV7KI95q9s2ZkMdUMaob/uxPnyTtptbcJsSzJ ID4K0S/jmTrIg== From: Frederic Weisbecker To: Peter Zijlstra , Thomas Gleixner Cc: LKML , Frederic Weisbecker , "Rafael J . Wysocki" , Yunfeng Ye , Marcelo Tosatti Subject: [PATCH 5/8] tick/nohz: Update nohz_full Kconfig help Date: Thu, 22 Apr 2021 14:01:55 +0200 Message-Id: <20210422120158.33629-6-frederic@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210422120158.33629-1-frederic@kernel.org> References: <20210422120158.33629-1-frederic@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org CONFIG_NO_HZ_FULL behaves just like CONFIG_NO_HZ_IDLE by default. Reassure distros about it. Signed-off-by: Frederic Weisbecker Cc: Yunfeng Ye Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Marcelo Tosatti Cc: Rafael J. Wysocki --- kernel/time/Kconfig | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 83e158d016ba..6649e1d2dba5 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -117,13 +117,14 @@ config NO_HZ_FULL the task mostly runs in userspace and has few kernel activity. You need to fill up the nohz_full boot parameter with the - desired range of dynticks CPUs. + desired range of dynticks CPUs to use it. This is implemented at + the expense of some overhead in user <-> kernel transitions: + syscalls, exceptions and interrupts. - This is implemented at the expense of some overhead in user <-> kernel - transitions: syscalls, exceptions and interrupts. Even when it's - dynamically off. + By default, without passing nohz_full parameter, this behaves just + like NO_HZ_IDLE. - Say N. + If you're a distro say Y. endchoice -- 2.25.1