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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id AF3C3C2BBCA for ; Fri, 28 Jun 2024 09:49:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 06E406B00B3; Fri, 28 Jun 2024 05:49:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 01CD76B00B4; Fri, 28 Jun 2024 05:49:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E26926B00B5; Fri, 28 Jun 2024 05:49:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id C534A6B00B3 for ; Fri, 28 Jun 2024 05:49:50 -0400 (EDT) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 67BDD1C2898 for ; Fri, 28 Jun 2024 09:49:50 +0000 (UTC) X-FDA: 82279825740.08.0F1BB6B Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf18.hostedemail.com (Postfix) with ESMTP id 99DCD1C000B for ; Fri, 28 Jun 2024 09:49:48 +0000 (UTC) Authentication-Results: imf18.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=zFZUKFBD; dkim=pass header.d=linutronix.de header.s=2020e header.b=5hz3Z5ll; spf=pass (imf18.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1719568165; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=MRTTaQMWsKNu0RAP3ZI6MFRNxnChl+5ZQXlF75X+APs=; b=YjfNFeYhIPC2wJVag7/7S7tzWlXwBwmPIeoES7cm0pfgogq/i9Gu8h5RZbsm7y8lDhqM9r Rteq3u8kGMd1I3gP/Df7i13ecmkxf+Y897DsDMQh0K7mOYH0TErTSoPFJH5O4eDGeQ0l8b 3lTxRu2939pFp31mCAeZqIXrEMLMEig= ARC-Authentication-Results: i=1; imf18.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=zFZUKFBD; dkim=pass header.d=linutronix.de header.s=2020e header.b=5hz3Z5ll; spf=pass (imf18.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1719568165; a=rsa-sha256; cv=none; b=vCD0qc4NRha/rehmmrBWTDFriMN1H4ipj25upyBQajZl2fAxPdqrrNIgrmnPDYaMuH5UDg Q+047D1fn7Jwe00lglEcTtXbWQ2MTuLELE5Lu3rhKES3P75tU8YPh79WPsUwt2U04XVhtH 4QGxItEqw4avj7XMwef+lQvIdhv6AbM= Date: Fri, 28 Jun 2024 11:49:44 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1719568185; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MRTTaQMWsKNu0RAP3ZI6MFRNxnChl+5ZQXlF75X+APs=; b=zFZUKFBDBKe8wJAVPU3rtJndgnbfwdk4iOY0YDtlGBoje+5TtFtm++Jh3weufcYuiK56LB KQh5vG447NbYrW4NhN8y6TfQb+Vn3GEKOWT67ojj9nbJE5wJMCB2fwIgarzq7B9D9nToVf e73isXlIBp2cX+0Zn2iOpE9L/ruEOMYncYPayHtNctEHce/iJK1/sq7dB2E6NxUyJ/3lNK sWksUD+qXTPegSHh/SBMcajqyKSab2o2z6lRV28I6G7lWK/R/U3CWqkuc9ueyYoM+n2Ljz iQ3P67dMEctnN1cKzirkOuqmw+cBr127Dx3GVlafSkO+ICYxs4evbSUEIlurWg== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1719568185; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=MRTTaQMWsKNu0RAP3ZI6MFRNxnChl+5ZQXlF75X+APs=; b=5hz3Z5llDJwqxv2R+8ZK/iuAI/paKRwd/5drxPDCxhTiq4aUXCLKVmW9A9mJ2wb8aUa03g iM7H7Pt3Pb8mqaAg== From: Sebastian Andrzej Siewior To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: Andrew Morton , Ben Segall , Daniel Bristot de Oliveira , Dietmar Eggemann , Ingo Molnar , Juri Lelli , Kent Overstreet , Klara Modin , Mel Gorman , Peter Zijlstra , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , Valentin Schneider , Vincent Guittot Subject: Re: [PATCH] sched/task_struct: Move alloc_tag to the end of the struct. Message-ID: <20240628094944.QwcHkf8J@linutronix.de> References: <20240621102750.oH9p1FQq@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240621102750.oH9p1FQq@linutronix.de> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 99DCD1C000B X-Stat-Signature: 7xcyzeqyuo816g6xwuj4ca5qwozou5ak X-Rspam-User: X-HE-Tag: 1719568188-506224 X-HE-Meta: U2FsdGVkX1/KHF9WdZl2qajtcz6Y6ZAd6PQyNBiOsBxtr3esTz0LYHtVuFVXO0RGNaIj4Os19R6GTMDeXpCuN20a1pDkMfWF6dDw74O06NgPqAt8IFFP0sDe+genBBcpAMqoL0mVkmBESbl8V4zjHaAK/pZJf0zkeOZw364NCwMQ7j2suUcQrJwRJkdYBYzux7gkFhhO3aUXCeWHNQYKYovbVTVNfk2QeFPuia90ZHV+ico1MH++NvmsXhEc7EA1MJ7iPWh8pb8yqxpiVW8pJtcsm0HPKKdxf8Ua+6H2gMa7yg79es4HpZcu7VmyTvIPNMew2abci4mtZpzYzLB2RUZTbbHdCCT7KeOvO7cjbpJJBbAFA3NnQzeAaUoiafogmKdoKYx/ZcUxYqHD7uveYxMlFU1HtLufN8Wgsq/dObFRCIBVpSmWZJHbMKZHEEK8I4qJZJPDiCp+eIhvm8lgHMFsGrhIrBJoCkL6STd/2LPWgG2mhx3Wo1KJwKfuVBpsyIq+Grj4Zd7zPDilD/bmOVbglR5LJbcGwvkyJUPeOmPu6ocXDriLGltpr6/s3EpXJIyaG/zr9QOuhrOXkWmI03vFmx0tr0G02al9IKspm/lOVSguvOR7MgLTeM5AOMUie1ncQPSbkV12bIDF8Vkb/gu+keeJHxN3PwfLUJ3X+DidzhKxVzMpF8Wh/SzzzJE2emhmBTMlenAW3xDC0P5oZiS++eKBSr1EgStMSZfYiNyywOJEr/suitKT0LWF2KDBPj0Qq5dM0td1pXD1UMX9VpuxVksS9brZ6MVI6xuXcQCFEP+ESAZh7+BSraJUg0wSH0Ip7L+nU7ohXyN+EdzeadI+Pg1BcwQRUTwm6gaQHRSZYBUMyBqb8/zhQST6MPQkE8ZiZZdRujVLK7GYuVopmNWkQ0/77AcBqhvqq03YBPp6kYAgW95giuiK7P6yyttya6dkhw5RlTBznvJWw/J LzMCwkEc gXGSaIYvwfhKN/ACgxNMkBLUz7Jiu/oRUT7Hj3V6udnLJ0K1CMYhGONM2Hkitd47mb3D5TgJh3NpGAj9mD6X2mGvi+eTNVLNOabvYqbUT3SAbp1qoSkp9E9JLaO0EeWMHxn45GKspqBWj2opqoqJbrqgB6aceblyG224Ks2pC1E9cAIxyUJgCD6kkwqM4MNlwSRNyENG3GuHZp4B3BpfRXsejn+NKZzXaOQ0nOh1SS4/dskuPRnFqO0Mjfg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2024-06-21 12:27:52 [+0200], To linux-mm@kvack.org wrote: > The alloc_tag member has been added to task_struct at the very > beginning. This is a pointer and on 64bit architectures it forces 4 byte > padding after `ptrace' and then forcing another another 4 byte padding > after `on_cpu'. A few members later, `se' requires a cacheline aligned > due to struct sched_avg resulting in 52 hole before `se'. > > This is the case on 64bit-SMP architectures. > The 52 byte hole can be avoided by moving alloc_tag away where it > currently resides. > > Move alloc_tag to the end of task_struct. There is likely a hole before > `thread' due to its alignment requirement and the previous members are > likely to be already pointer-aligned. > > Fixes: 22d407b164ff7 ("lib: add allocation tagging support for memory allocation profiling") > Signed-off-by: Sebastian Andrzej Siewior Could we please get this merged and worry about possible performance regression later? Or once there is a test case or an idea where this pointer might fit better but clearly the current situation is worse. Sebastian