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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 2445F106B53F for ; Wed, 25 Mar 2026 13:54:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=hA/RcDLnfM70e9u18PcuMcikLc3YOOmToizAbJtUCjw=; b=HoRc8xuYsyCh+wMeGHtEL0u9fS BchW0BkssmPI1ucVrJj7MMZnd4wN6/mouf1ylrJXpwAXoZWgrFYQyAzEhNBxZL1Ui2ItBPTStjRrV XrsvgWnomEvRloOTCb9TI22Hohg/T6xwmspqQUlkADUVTtkgK0vXXpcLkze8dMWdaVPWFUHfC4XVe KI1LjcRhwaI6yBVzH23D2cf4OHUdF0y5I2+GsBMUkuF9OWVbhftmvO+OYty86QkxMaMsTehb6jWs/ FB5aDsshtM/RfSqgowZQSz9Jv8/yDCoB5kOQTmNxhs1ZJiKAve02L7oZ4Pk7txP+y7WxRutnKO/uc ITHKsqEg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5OgM-00000003VHO-0Jjz; Wed, 25 Mar 2026 13:54:02 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1w5OgJ-00000003VGS-27X8 for linux-arm-kernel@lists.infradead.org; Wed, 25 Mar 2026 13:54:00 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id EA21E1CDD; Wed, 25 Mar 2026 06:53:50 -0700 (PDT) Received: from arm.com (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 712F83F836; Wed, 25 Mar 2026 06:53:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1774446836; bh=rTpz50E+4PJ6RioGt1JBhmHx0qMuH5Sl7wjDXLEJHn8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=F3S2AixyqhIuvb8mv8t2FHXLeYL9B2PwbydxQJsk+j50mWFPm3DNRdGMWKQ16/2k6 weCqqFChyZQPX537W7n5cnvAWcGK9jd+cQdtzw8wzA9Eh5HfC5UyqLTWEbBLh/76EH xjaFdyHFtCq85BBXLQ7eZIVbpTx5hrKWok8PXOv8= Date: Wed, 25 Mar 2026 13:53:50 +0000 From: Catalin Marinas To: David Laight Cc: Ankur Arora , Andrew Morton , linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, bpf@vger.kernel.org, arnd@arndb.de, will@kernel.org, peterz@infradead.org, mark.rutland@arm.com, harisokn@amazon.com, cl@gentwo.org, ast@kernel.org, rafael@kernel.org, daniel.lezcano@linaro.org, memxor@gmail.com, zhenglifeng1@huawei.com, xueshuai@linux.alibaba.com, rdunlap@infradead.org, joao.m.martins@oracle.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com Subject: Re: [PATCH v10 00/12] barrier: Add smp_cond_load_{relaxed,acquire}_timeout() Message-ID: References: <20260316013651.3225328-1-ankur.a.arora@oracle.com> <20260315184925.b6f93386e918ca79614843e3@linux-foundation.org> <874imftol4.fsf@oracle.com> <20260316233712.7cbfac27@pumpkin> <87ms07rlp9.fsf@oracle.com> <20260317091705.5a64fc56@pumpkin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260317091705.5a64fc56@pumpkin> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260325_065359_584256_7B25BB8A X-CRM114-Status: GOOD ( 12.85 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Mar 17, 2026 at 09:17:05AM +0000, David Laight wrote: > On Mon, 16 Mar 2026 23:53:22 -0700 > Ankur Arora wrote: > > David Laight writes: > > > On arm64 I think you could use explicit sev and wfe - but that will wake all > > > 'sleeping' cpu; and you may not want the 'thundering herd'. > > > > Wouldn't we still have the same narrow window where the CPU disregards the IPI? > > You need a 'sevl' in the interrupt exit path. No need to, see the rule below in https://developer.arm.com/documentation/ddi0487/maa/2983-beijhbbd: R_XRZRK The Event Register for a PE is set by any of the following: [...] - An exception return. -- Catalin