From owner-freebsd-net@FreeBSD.ORG Wed Jan 29 22:21:22 2014 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 6B0457D4 for ; Wed, 29 Jan 2014 22:21:22 +0000 (UTC) Received: from mail-qc0-x22a.google.com (mail-qc0-x22a.google.com [IPv6:2607:f8b0:400d:c01::22a]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 2A19D1CED for ; Wed, 29 Jan 2014 22:21:22 +0000 (UTC) Received: by mail-qc0-f170.google.com with SMTP id e9so3859618qcy.1 for ; Wed, 29 Jan 2014 14:21:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=UnyI2eYYxSEcf7NFs3EDoEZfO6pNK1Ca8wpGCcfymGE=; b=pmgHc5QV8KHTmF2/SPKALh0qx25Adtrgx0FOEBCRWWrkiSTZ94nRURq7e2fgpQh9gL Hjzjya9Xeg3m3jz3CgscLPx9oCaT6A+Oyno6w/JvhNcg57zRoEJm6potOb42gbGFRWgW /hMTM7sFaqIoIsUziFvqA1UF4KZzjzlzIfETKkQe9s4DSnMadH/rJINMvo+j+9Hs8nsa ncH6OI4pLP1kK8rl3rrwpnCsQIx/EyW08r6CRsRx65E3jGerpwpyPQVS40ImOKO372wL xPZY9cXe1QwSkWQXWphPVRjM83MrpdKtFvLbOEPUr1FUk0IxVCE5BSkAEwGe3L5z/YEj 1YEw== MIME-Version: 1.0 X-Received: by 10.224.52.3 with SMTP id f3mr16517773qag.26.1391034081362; Wed, 29 Jan 2014 14:21:21 -0800 (PST) Sender: adrian.chadd@gmail.com Received: by 10.224.52.8 with HTTP; Wed, 29 Jan 2014 14:21:21 -0800 (PST) In-Reply-To: <21225.20047.947384.390241@khavrinen.csail.mit.edu> References: <21225.20047.947384.390241@khavrinen.csail.mit.edu> Date: Wed, 29 Jan 2014 14:21:21 -0800 X-Google-Sender-Auth: h3t7oDAulNFeRilUMr0HheGsL3c Message-ID: Subject: Re: Big physically contiguous mbuf clusters From: Adrian Chadd To: Garrett Wollman Content-Type: text/plain; charset=ISO-8859-1 Cc: FreeBSD Net X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 29 Jan 2014 22:21:22 -0000 Hi, On 29 January 2014 10:54, Garrett Wollman wrote: > Resolved: that mbuf clusters longer than one page ought not be > supported. There is too much physical-memory fragmentation for them > to be of use on a moderately active server. 9k mbufs are especially > bad, since in the fragmented case they waste 3k per allocation. I've been wondering whether it'd be feasible to teach the physical memory allocator about >page sized allocations and to create zones of slightly more physically contiguous memory. For servers with lots of memory we could then keep these around and only dip into them for temporary allocations (eg not VM pages that may be held for some unknown amount of time.) Question is - can we enforce that kind of behaviour? -a