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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 4F6AEC432C0 for ; Wed, 20 Nov 2019 21:05:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0DA582075E for ; Wed, 20 Nov 2019 21:05:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="faVO0Z2X" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726080AbfKTVFX (ORCPT ); Wed, 20 Nov 2019 16:05:23 -0500 Received: from merlin.infradead.org ([205.233.59.134]:48158 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725787AbfKTVFX (ORCPT ); Wed, 20 Nov 2019 16:05:23 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=V6mmgxtkXDcIQX6qcqCxCHnDmuVgMT2R3iVxZ3C6yPE=; b=faVO0Z2XZSMV08kbBojdX5+/b ifwe+BJWp/QGCOQIWP3sMMKcJaMRH9nOqeh7yQcbLpwaLlSQNdiENL3VlgdsQ227vj5eANPQ23MuL iYvzSnvd5b7A4K7NhrnLL3kpiDDufJwztgmuom3zK9RsueuB3gtjGc+8eQEbUUtiKWbYsViSxCn5X eZzsOVi1Z6jXHqNKtw8gaQcgCGc2jBMdjsu+s8Bd4F/Hhr+1xptGmlIMhpInlP9QtoAEDYjS+J6sp ilZSLfSqeWBBV5VrLi9rd+rbnMjRyYfw6dcOFNjUxI+3WfGPwGvW3lXVO7c9iKEXRLcWvQzC8iCU7 cTMiVW3SQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=worktop.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1iXX9Y-0000QA-65; Wed, 20 Nov 2019 21:04:44 +0000 Received: by worktop.programming.kicks-ass.net (Postfix, from userid 1000) id F11B3980E2F; Wed, 20 Nov 2019 22:04:40 +0100 (CET) Date: Wed, 20 Nov 2019 22:04:40 +0100 From: Peter Zijlstra To: Ingo Molnar Cc: Frederic Weisbecker , LKML , Jacek Anaszewski , Wanpeng Li , "Rafael J . Wysocki" , Benjamin Herrenschmidt , Rik van Riel , Thomas Gleixner , Yauheni Kaliuta , Viresh Kumar , Pavel Machek Subject: Re: [PATCH 1/6] sched/cputime: Support other fields on kcpustat_field() Message-ID: <20191120210440.GR3079@worktop.programming.kicks-ass.net> References: <20191119232218.4206-1-frederic@kernel.org> <20191119232218.4206-2-frederic@kernel.org> <20191120115142.GA89662@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191120115142.GA89662@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 20, 2019 at 12:51:42PM +0100, Ingo Molnar wrote: > * Frederic Weisbecker wrote: > > + /* > > + * Nice VS unnice cputime accounting may be inaccurate if > > + * the nice value has changed since the last vtime update. > > + * But proper fix would involve interrupting target on nice > > + * updates which is a no go on nohz_full. > > Well, we actually already interrupt the target in both sys_nice() and > sys_setpriority() etc. syscall variants: we call set_user_nice() which > calls resched_curr() and the task is sent an IPI and runs through a > reschedule. I think we can easily avoid doing that IPI when we find it is the only task on that runqueue. Which is exactly the case for NOHZ_FULL.