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 4604EC43381 for ; Wed, 20 Mar 2019 18:54:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1E1A121841 for ; Wed, 20 Mar 2019 18:54:02 +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="E4Zgc0H9" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727465AbfCTSx5 (ORCPT ); Wed, 20 Mar 2019 14:53:57 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:42168 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727099AbfCTSx4 (ORCPT ); Wed, 20 Mar 2019 14:53:56 -0400 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=19J+W7mnzMxofEiVeKGPeMBVF0b3b1HaVTXfNyGBA6g=; b=E4Zgc0H9T3r8B3MviIDF03WoP /HtoUhhrOcbhOuSMgLsAiKywl8ntQbDZot9vppf3j1ZhHpVBs8dBIQ+oWlbfzGvq5ObJh4Zm9ITRK vBPhCnuJwODhSL3923phSEgySz2SifsDpBDvrPjW7w+MfMhUJaeEZRRYe8BlvgkZSoP2j+rNaios8 3nZY5KR49A3NzOIBdLirAG6u0jdT3wQ7vhHSsb0x3QE2zJrLQ4MHfWLLdwqszN8zzsZKoufs611n+ KwwrABaK4gxbwmNaB1W67rg3wMhahYvPxzOj4YmP7rhOMbilxpFfL5OSCcgC31pQSYkueD/rH6MIa meexl8+1A==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1h6gLT-0000z4-IC; Wed, 20 Mar 2019 18:53:47 +0000 Date: Wed, 20 Mar 2019 11:53:47 -0700 From: Matthew Wilcox To: Vlastimil Babka Cc: Christopher Lameter , linux-mm@kvack.org, Pekka Enberg , David Rientjes , Joonsoo Kim , Ming Lei , Dave Chinner , "Darrick J . Wong" , Christoph Hellwig , Michal Hocko , linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org Subject: Re: [RFC 0/2] guarantee natural alignment for kmalloc() Message-ID: <20190320185347.GZ19508@bombadil.infradead.org> References: <20190319211108.15495-1-vbabka@suse.cz> <01000169988d4e34-b4178f68-c390-472b-b62f-a57a4f459a76-000000@email.amazonses.com> <5d7fee9c-1a80-6ac9-ac1d-b1ce05ed27a8@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5d7fee9c-1a80-6ac9-ac1d-b1ce05ed27a8@suse.cz> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Wed, Mar 20, 2019 at 09:48:47AM +0100, Vlastimil Babka wrote: > Natural alignment to size is rather well defined, no? Would anyone ever > assume a larger one, for what reason? > It's now where some make assumptions (even unknowingly) for natural > There are two 'odd' sizes 96 and 192, which will keep cacheline size > alignment, would anyone really expect more than 64 bytes? Presumably 96 will keep being aligned to 32 bytes, as aligning 96 to 64 just results in 128-byte allocations.