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_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 700B2C004D3 for ; Wed, 24 Oct 2018 10:15:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 31BAA20831 for ; Wed, 24 Oct 2018 10:15:24 +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="faq0b/TH" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31BAA20831 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727368AbeJXSmv (ORCPT ); Wed, 24 Oct 2018 14:42:51 -0400 Received: from merlin.infradead.org ([205.233.59.134]:36028 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726301AbeJXSmv (ORCPT ); Wed, 24 Oct 2018 14:42:51 -0400 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=6YdHeJ40st/wDoNAAH8y60ebo1dhqAW8+Uuit+CFc5U=; b=faq0b/TH5ULtPAR+Yk9y/vpf+ xmvUsD1vfgvqNKFIvriXnw/FGCnlwYtzQcp6py5o8C9n5AEOMHrQ3Xs/VyajhuD+l3Yy2Ew0altEM 4sE27EyVTQdhipOzw4cZmC1k6clK2sd7b3COicF3x7lPikZmGSbZqX/5pdM8BwcHjKpmri+OAZotM BNyK34qjO6lTwqAvWnfFcMsDhTk7UfS0eu4rgYfn73mUec+9VHbbhKS79KAUXg6s77orQQRapjIer 28g85GCGfZdahlOOiO9y/TDrABGQD+U8VHyjlJ4342Jq1XG9D5pejjl4DAmiJ4M9i8E599iqt0/Fw 68T1wcWww==; Received: from [185.7.230.213] (helo=worktop) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gFGC4-0007L2-AH; Wed, 24 Oct 2018 10:15:17 +0000 Received: by worktop (Postfix, from userid 1000) id 0EDF86E08B3; Wed, 24 Oct 2018 12:15:08 +0200 (CEST) Date: Wed, 24 Oct 2018 12:15:08 +0200 From: Peter Zijlstra To: Srikar Dronamraju Cc: Mel Gorman , Ingo Molnar , LKML , Rik van Riel , Yi Wang , zhong.weidong@zte.com.cn, Yi Liu , Frederic Weisbecker , Thomas Gleixner Subject: Re: [PATCH v2] sched/core: Don't mix isolcpus and housekeeping CPUs Message-ID: <20181024101508.GP3109@worktop.c.hoisthospitality.com> References: <1540350169-18581-1-git-send-email-srikar@linux.vnet.ibm.com> <20181024085636.GB23537@techsingularity.net> <20181024094646.GA18466@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181024094646.GA18466@linux.vnet.ibm.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 24, 2018 at 03:16:46PM +0530, Srikar Dronamraju wrote: > * Mel Gorman [2018-10-24 09:56:36]: > > > On Wed, Oct 24, 2018 at 08:32:49AM +0530, Srikar Dronamraju wrote: > > It would certainly be a bit odd because the > > application is asking for some protection but no guarantees are given > > and the application is not made aware via an error code that there is a > > problem. Asking the application to parse dmesg hoping to find the right > > error message is going to be fragile. > > Its a actually a good question. > What should we be doing if a mix of isolcpus and housekeeping (aka > non-isolcpus) is given in the mask. > > Right now as you pointed, there is no easy way for the application to know > which are the non-isolcpus to set its affinity. cpusets effective_cpus and > cpus_allowed both will contain isolcpus too. The easy option is to not use isolcpus :-) It is a horrifically bad interface.