From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [net-next PATCH V2 1/9] net: frag evictor, avoid killing warm frag queues Date: Fri, 30 Nov 2012 06:57:25 -0800 Message-ID: <1354287445.3299.72.camel@edumazet-glaptop> References: <20121129161019.17754.29670.stgit@dragon> <20121129161052.17754.85017.stgit@dragon> <20121129.124427.1093031685966728935.davem@davemloft.net> <1354227470.11754.348.camel@localhost> <1354276891.11754.424.camel@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Miller , fw@strlen.de, netdev@vger.kernel.org, pablo@netfilter.org, tgraf@suug.ch, amwang@redhat.com, kaber@trash.net, paulmck@linux.vnet.ibm.com, herbert@gondor.hengli.com.au, David Laight To: Jesper Dangaard Brouer Return-path: Received: from mail-ie0-f174.google.com ([209.85.223.174]:60246 "EHLO mail-ie0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753949Ab2K3O53 (ORCPT ); Fri, 30 Nov 2012 09:57:29 -0500 Received: by mail-ie0-f174.google.com with SMTP id c11so739955ieb.19 for ; Fri, 30 Nov 2012 06:57:29 -0800 (PST) In-Reply-To: <1354276891.11754.424.camel@localhost> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, 2012-11-30 at 13:01 +0100, Jesper Dangaard Brouer wrote: > As the existing entries in the frag queues, are still being allowed > packets through (even when the memory limit is exceeded). In > worst-case, as DaveM explained, this can be as much as 100KBytes per > entry (for 64K fragments). Some NIC uses a plain page to hold an ethernet frame. Consider an UDP packet using 512 bytes frags, the resulting packet after reassembly can use 128 pages. Thats 512 KB of memory on x86.