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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 7FE6FC10F03 for ; Thu, 25 Apr 2019 12:04:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id B9D0D2084B for ; Thu, 25 Apr 2019 12:04:17 +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="itKCf7Um" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B9D0D2084B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44qbSv0fPKzDqZk for ; Thu, 25 Apr 2019 22:04:15 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=none (mailfrom) smtp.mailfrom=infradead.org (client-ip=2607:7c80:54:e::133; helo=bombadil.infradead.org; envelope-from=peterz@infradead.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=infradead.org header.i=@infradead.org header.b="itKCf7Um"; dkim-atps=neutral Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44qbQr07yvzDqYK for ; Thu, 25 Apr 2019 22:02:26 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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=1qJZVo8k8mfgYlmp5TlLC0v12e3deJx7zXBcLuuf09Y=; b=itKCf7UmuYpBuLWRVW2Bbm8gh Eu+0cXhmneoXZOnbipmmftF1WjzE0G/wpyQ38Uy9pfrFEaqqWy45fCY+vvi/by/YC31pQj0y/7lHp ygA+X46hJbobIbWwVh6nNxJ3sxwS1L3EfifLAgx9ylVR/1bVGwEVa97r7scrmrcquEceVsbF3qbxt g1mxIOpaZ362uDYeMnclHAN2Vg/uRhmD/Rh0CAwoRtrxdm4mcXrbyjD7F5e5Ud15VUxrmgYVdIcV8 VDjlxiZMb+502NldtQH3Jb+AQwTNz0xu+aRZIkb6vN8AiVzusMN98hHOEqkD+os7O1i0Gkd5Apo8u +VshWaI7A==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJd55-00010Y-34; Thu, 25 Apr 2019 12:02:23 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9295A29C22B16; Thu, 25 Apr 2019 14:02:21 +0200 (CEST) Date: Thu, 25 Apr 2019 14:02:21 +0200 From: Peter Zijlstra To: Nicholas Piggin Subject: Re: [PATCH v2 3/5] kernel/cpu: Allow non-zero CPU to be primary for suspend / kexec freeze Message-ID: <20190425120221.GR4038@hirez.programming.kicks-ass.net> References: <20190411033448.20842-1-npiggin@gmail.com> <20190411033448.20842-4-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190411033448.20842-4-npiggin@gmail.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arch@vger.kernel.org, Frederic Weisbecker , "Rafael J . Wysocki" , linux-kernel@vger.kernel.org, Ingo Molnar , Thomas Gleixner , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Thu, Apr 11, 2019 at 01:34:46PM +1000, Nicholas Piggin wrote: > This patch provides an arch option, ARCH_SUSPEND_NONZERO_CPU, to > opt-in to allowing suspend to occur on one of the housekeeping CPUs > rather than hardcoded CPU0. > > This will allow CPU0 to be a nohz_full CPU with a later change. > > It may be possible for platforms with hardware/firmware restrictions > on suspend/wake effectively support this by handing off the final > stage to CPU0 when kernel housekeeping is no longer required. Another > option is to make housekeeping / nohz_full mask dynamic at runtime, > but the complexity could not be justified at this time. Should we not tie this into whatever already allows an achitecture to hotplug CPU-0? For instance, x86 default disallows this but has cpu0_hotpluggable to allow this. Presumably POWER already allows hotplugging CPU-0 ?