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[2607:7c80:54:e::133]) by mx.google.com with ESMTPS id 136si2240943pfc.170.2019.03.20.11.53.49 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Mar 2019 11:53:49 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) client-ip=2607:7c80:54:e::133; Authentication-Results: mx.google.com; dkim=pass header.i=@infradead.org header.s=bombadil.20170209 header.b=E4Zgc0H9; spf=pass (google.com: best guess record for domain of willy@infradead.org designates 2607:7c80:54:e::133 as permitted sender) smtp.mailfrom=willy@infradead.org 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) 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: 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.