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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 2263FC5519F for ; Wed, 25 Nov 2020 11:08:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 785D3206E5 for ; Wed, 25 Nov 2020 11:08:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="AfaAg3Jb" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727109AbgKYLIZ (ORCPT ); Wed, 25 Nov 2020 06:08:25 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36868 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725792AbgKYLIX (ORCPT ); Wed, 25 Nov 2020 06:08:23 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A3DFDC0613D4 for ; Wed, 25 Nov 2020 03:08:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=gAbPhRE5NmWykLnN7qEqkHtVQT17OqOEfTcOqr5l+bk=; b=AfaAg3JbEPdTQujrCHinuZGkTD tuDeRxyDhVtf9WhZNocmI3rVLmobKfzBN/VI6Da/vmHbmFcCpI0/z+Rz8z+a4X0qv/0wXikr40Vs9 4jZBg9Hsziw7rJ0S2ZsNZtlTcD+jCuhqUwE/O+P49iuuAc/3TKEPC2qpfVao3XdFyAlRCxuHSt9V+ zW7wCOza5d43jnovsi3I2RYEOQ9FdIoQTE+4NMpEw1PfSVkN0l0ZUXHZAdUVgj3xg3B/AZH1FKcFj pG+hDjPdBamf3OLjxG852wdBWM4SrU097AC1H54ZcXfrH09pNaesBui6PGVkgarAQd6o1GFyICNuT SieeHgXQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1khsdm-00070r-Gw; Wed, 25 Nov 2020 11:07:16 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0F2FE300DAE; Wed, 25 Nov 2020 12:07:09 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D6BBA20D6FE70; Wed, 25 Nov 2020 12:07:09 +0100 (CET) Date: Wed, 25 Nov 2020 12:07:09 +0100 From: Peter Zijlstra To: "Joel Fernandes (Google)" Cc: Nishanth Aravamudan , Julien Desfossez , Tim Chen , Vineeth Pillai , Aaron Lu , Aubrey Li , tglx@linutronix.de, linux-kernel@vger.kernel.org, mingo@kernel.org, torvalds@linux-foundation.org, fweisbec@gmail.com, keescook@chromium.org, kerrnel@google.com, Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini , vineeth@bitbyteword.org, Chen Yu , Christian Brauner , Agata Gruza , Antonio Gomez Iglesias , graf@amazon.com, konrad.wilk@oracle.com, dfaggioli@suse.com, pjt@google.com, rostedt@goodmis.org, derkling@google.com, benbjiang@tencent.com, Alexandre Chartre , James.Bottomley@hansenpartnership.com, OWeisse@umich.edu, Dhaval Giani , Junaid Shahid , jsbarnes@google.com, chris.hyser@oracle.com, Ben Segall , Josh Don , Hao Luo , Tom Lendacky , Aubrey Li , "Paul E. McKenney" , Tim Chen Subject: Re: [PATCH -tip 22/32] sched: Split the cookie and setup per-task cookie on fork Message-ID: <20201125110709.GR2414@hirez.programming.kicks-ass.net> References: <20201117232003.3580179-1-joel@joelfernandes.org> <20201117232003.3580179-23-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201117232003.3580179-23-joel@joelfernandes.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 17, 2020 at 06:19:52PM -0500, Joel Fernandes (Google) wrote: > Also, for the per-task cookie, it will get weird if we use pointers of any > emphemeral objects. For this reason, introduce a refcounted object who's sole > purpose is to assign unique cookie value by way of the object's pointer. Might be useful to explain why exactly none of the many pid_t's are good enough.