Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753166Ab1F1XfV (ORCPT ); Tue, 28 Jun 2011 19:35:21 -0400 Received: from shards.monkeyblade.net ([198.137.202.13]:34233 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751854Ab1F1XfR (ORCPT ); Tue, 28 Jun 2011 19:35:17 -0400 Date: Tue, 28 Jun 2011 16:35:08 -0700 (PDT) Message-Id: <20110628.163508.222352070705159851.davem@davemloft.net> To: mashirle@us.ibm.com Cc: mst@redhat.com, eric.dumazet@gmail.com, avi@redhat.com, arnd@arndb.de, netdev@vger.kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH V7 2/4 net-next] skbuff: Add userspace zero-copy buffers in skb From: David Miller In-Reply-To: <1309279892.3559.6.camel@localhost.localdomain> References: <1309189510.21764.1.camel@localhost.localdomain> <20110627.155426.51839633424542723.davem@davemloft.net> <1309279892.3559.6.camel@localhost.localdomain> X-Mailer: Mew version 6.3 on Emacs 23.2 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (shards.monkeyblade.net [198.137.202.13]); Tue, 28 Jun 2011 16:35:10 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1313 Lines: 32 From: Shirley Ma Date: Tue, 28 Jun 2011 09:51:32 -0700 > On Mon, 2011-06-27 at 15:54 -0700, David Miller wrote: >> From: Shirley Ma >> Date: Mon, 27 Jun 2011 08:45:10 -0700 >> >> > To support skb zero-copy, a pointer is needed to add to skb share >> info. >> > Do you agree with this approach? If not, do you have any other >> > suggestions? >> >> I really can't form an opinion unless I am shown the complete >> implementation, what this give us in return, what the impact is, etc. .. > You can see the overall CPU saved 50% w/i zero-copy. > > The impact is every skb allocation consumed one more pointer in skb > share info, and a pointer check in skb release when last reference is > gone. > > For skb clone, skb expand private head and skb copy, it still keeps copy > the buffers to kernel, so we can avoid user application, like tcpdump to > hold the user-space buffers too long. Ok, now show me the "complete implementation". I'm as interested in the code as I am in the numbers, that's why I asked for both. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/