From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D6004C28EBD for ; Fri, 7 Jun 2019 01:54:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B305720868 for ; Fri, 7 Jun 2019 01:54:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727782AbfFGByX (ORCPT ); Thu, 6 Jun 2019 21:54:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52386 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725784AbfFGByX (ORCPT ); Thu, 6 Jun 2019 21:54:23 -0400 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 2179F87621; Fri, 7 Jun 2019 01:54:23 +0000 (UTC) Received: from localhost (ovpn-112-18.ams2.redhat.com [10.36.112.18]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C9EF4784B3; Fri, 7 Jun 2019 01:54:20 +0000 (UTC) Date: Fri, 7 Jun 2019 03:54:16 +0200 From: Stefano Brivio To: David Ahern Cc: Martin Lau , David Miller , Jianlin Shi , Wei Wang , Eric Dumazet , "netdev@vger.kernel.org" Subject: Re: [PATCH net 1/2] ipv6: Dump route exceptions too in rt6_dump_route() Message-ID: <20190607035416.299f8f4b@redhat.com> In-Reply-To: References: <085ce9fbe0206be0d1d090b36e656aa89cef3d98.1559851514.git.sbrivio@redhat.com> <20190606214456.orxy6274xryxyfww@kafai-mbp.dhcp.thefacebook.com> <20190607001747.4ced02c7@redhat.com> <20190606223707.s2fyhnqnt3ygdtdj@kafai-mbp.dhcp.thefacebook.com> Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Fri, 07 Jun 2019 01:54:23 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, 6 Jun 2019 16:48:51 -0600 David Ahern wrote: > On 6/6/19 4:37 PM, Martin Lau wrote: > >> I don't think that can happen in practice, or at least I haven't found a > >> way to create enough valid exceptions for the same node. > > That I am not sure. It is not unusual to have many pmtu exceptions in > > a gateway node. > > > > yes. > > Stefano: you could generalize this test script > http://patchwork.ozlabs.org/patch/1110802/ > to have N-remote hosts Right, thanks for the pointer. I ended up doing something like that in pmtu.sh, and it turns out that, starting from 25 exceptions in the same node, iproute2 doesn't actually retry with a larger buffer. As Martin predicted (thanks!) the dump doesn't terminate. I tested a version that counts the number of routes in a partial dump and skips them on the next one with 10,000 entries, dump terminates and entries count is consistent (at some point, the buckets are just full, and number of entries doesn't increase any longer). Unfortunately, the setup of the test takes a few minutes, so I wouldn't include it (at least as it is) in the selftest. I'll post that as v2 soon. -- Stefano