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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00C87C6FD1D for ; Tue, 21 Mar 2023 15:41:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231766AbjCUPlO (ORCPT ); Tue, 21 Mar 2023 11:41:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49726 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231582AbjCUPlH (ORCPT ); Tue, 21 Mar 2023 11:41:07 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1FA5322011 for ; Tue, 21 Mar 2023 08:40:55 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=E1W0yEv2L9EaroT9MRj0YrOythcNd0CZtw7NCo2aZTA=; b=IRG1DxC+w8Fzg1pvXUHgP05wRm sQ2dLrx8SXeMSYVT4WsMQaaDjPNFLgrP6nQfM+PTwWmgv4bgcJYJoIm0+lwasA2G5WpTcokiFCQhl rT49CZueIzspHXf8dISuJqVUZoBog94MwAKzfANeSY/IKnbRth2KdOdVgpqROn257kVUOnQQ5A0q1 qOs+o0RQCAoyyKM9vGaa6klA4RqpsFHaUaM7q0xSty3oM15Hricwiev9vKZ2yi5ODFBhfxdoZOpI2 vL3IFlRCIQr8z2gnCGMEwDMNx4aRJtczTOdJa+rkUMuuy8ebnBMO8+Qda/I3HJ0FKI6t9lFfXBskJ K6cuQR1w==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1pee6L-004Ife-1m; Tue, 21 Mar 2023 15:40:42 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id F3EFA30006D; Tue, 21 Mar 2023 16:40:40 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DB1EA240D2A01; Tue, 21 Mar 2023 16:40:40 +0100 (CET) Date: Tue, 21 Mar 2023 16:40:40 +0100 From: Peter Zijlstra To: Anna-Maria Behnsen Cc: linux-kernel@vger.kernel.org, John Stultz , Thomas Gleixner , Eric Dumazet , "Rafael J . Wysocki" , Arjan van de Ven , "Paul E . McKenney" , Frederic Weisbecker , Rik van Riel Subject: Re: [PATCH v5 16/18] timer: Implement the hierarchical pull model Message-ID: <20230321154040.GC2272870@hirez.programming.kicks-ass.net> References: <20230301141744.16063-1-anna-maria@linutronix.de> <20230301141744.16063-17-anna-maria@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230301141744.16063-17-anna-maria@linutronix.de> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 01, 2023 at 03:17:42PM +0100, Anna-Maria Behnsen wrote: > +static bool tmigr_requires_handle_remote_up(struct tmigr_group *group, > + struct tmigr_group *child, > + void *ptr) > +{ > + struct tmigr_remote_data *data = ptr; > + u32 childmask; > + > + childmask = data->childmask; > + > + /* > + * Handle the group only if child is the migrator or if the group > + * has no migrator. Otherwise the group is active and is handled by > + * its own migrator. > + */ > + if (!tmigr_check_migrator(group, childmask)) > + return true; > + > + /* > + * Racy lockless check for next_expiry > + */ > + if (data->now >= group->next_expiry) { I'm not far enough along to tell; but on 32bit this can/will suffer from split loads and basically turn into a random number generator. I'm presuming the 'check = 1' thing here covers that case? > + data->check = 1; > + return true; > + } > + > + /* Update of childmask for next level */ > + data->childmask = group->childmask; > + return false; > +}