From mboxrd@z Thu Jan 1 00:00:00 1970 From: Steffen Klassert Subject: Re: [PATCH 2/4] ipv4: Update pmtu informations on inetpeer only for output routes Date: Fri, 14 Oct 2011 08:34:23 +0200 Message-ID: <20111014063423.GQ1830@secunet.com> References: <20111011110842.GC1830@secunet.com> <20111011111027.GE1830@secunet.com> <20111012.170805.2172804476308993385.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: netdev@vger.kernel.org To: David Miller Return-path: Received: from a.mx.secunet.com ([195.81.216.161]:47267 "EHLO a.mx.secunet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751300Ab1JNGe0 (ORCPT ); Fri, 14 Oct 2011 02:34:26 -0400 Content-Disposition: inline In-Reply-To: <20111012.170805.2172804476308993385.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Oct 12, 2011 at 05:08:05PM -0400, David Miller wrote: > > You really can't do this, it's going to kill all of the memory savings from > storing metrics in the inetpeer cache. > > Every input route is going to have it's metrics COW'd with this change. > Ok, I missed this completely. So if input and output routes share the inetpeer information and we don't want to copy, we might not use the (learned) pmtu informations on the inetpeer for input routes. So for input routes, dst_mtu() could return dst->ops->default_mtu() instead of the mtu informations stored on the metric. Are there other (better) solutions?