From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751647AbbDPEU1 (ORCPT ); Thu, 16 Apr 2015 00:20:27 -0400 Received: from helcar.hengli.com.au ([209.40.204.226]:39379 "EHLO helcar.hengli.com.au" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750755AbbDPEUW (ORCPT ); Thu, 16 Apr 2015 00:20:22 -0400 Date: Thu, 16 Apr 2015 12:20:06 +0800 From: Herbert Xu To: Eric Dumazet Cc: stefano.stabellini@eu.citrix.com, george.dunlap@eu.citrix.com, Jonathan.Davies@citrix.com, xen-devel@lists.xensource.com, wei.liu2@citrix.com, Ian.Campbell@citrix.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, edumazet@google.com, paul.durrant@citrix.com, christoffer.dall@linaro.org, felipe.franciosi@citrix.com, linux-arm-kernel@lists.infradead.org, david.vrabel@citrix.com Subject: Re: [Xen-devel] "tcp: refine TSO autosizing" causes performance regression on Xen Message-ID: <20150416042005.GA12179@gondor.apana.org.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1429121867.7346.136.camel@edumazet-glaptop2.roam.corp.google.com> Organization: Core X-Newsgroups: apana.lists.os.linux.kernel,apana.lists.os.linux.netdev,apana.lists.os.xen.devel User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric Dumazet wrote: > > We already have netdev->gso_max_size and netdev->gso_max_segs > which are cached into sk->sk_gso_max_size & sk->sk_gso_max_segs It is quite dangerous to attempt tricks like this because a tc redirection or netfilter nat could change the destination device rendering such hints incorrect. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt From mboxrd@z Thu Jan 1 00:00:00 1970 From: herbert@gondor.apana.org.au (Herbert Xu) Date: Thu, 16 Apr 2015 12:20:06 +0800 Subject: [Xen-devel] "tcp: refine TSO autosizing" causes performance regression on Xen In-Reply-To: <1429121867.7346.136.camel@edumazet-glaptop2.roam.corp.google.com> Message-ID: <20150416042005.GA12179@gondor.apana.org.au> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Eric Dumazet wrote: > > We already have netdev->gso_max_size and netdev->gso_max_segs > which are cached into sk->sk_gso_max_size & sk->sk_gso_max_segs It is quite dangerous to attempt tricks like this because a tc redirection or netfilter nat could change the destination device rendering such hints incorrect. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt