From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [net-next][PATCH] tcp: probe timer MUST not less than 5 minuter for tcp PMTU Date: Sat, 2 Jun 2018 06:19:22 -0400 Message-ID: References: <1527851039-6626-1-git-send-email-lirongqing@baidu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: Li RongQing , netdev@vger.kernel.org Return-path: Received: from mail-pl0-f67.google.com ([209.85.160.67]:47035 "EHLO mail-pl0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750886AbeFBKTZ (ORCPT ); Sat, 2 Jun 2018 06:19:25 -0400 Received: by mail-pl0-f67.google.com with SMTP id 30-v6so16752313pld.13 for ; Sat, 02 Jun 2018 03:19:25 -0700 (PDT) In-Reply-To: <1527851039-6626-1-git-send-email-lirongqing@baidu.com> Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: On 06/01/2018 07:03 AM, Li RongQing wrote: > RFC4821 say: The value for this timer MUST NOT be less than > 5 minutes and is recommended to be 10 minutes, per RFC 1981. > > Signed-off-by: Li RongQing > --- > net/ipv4/sysctl_net_ipv4.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c > index d2eed3ddcb0a..ed8952bb6874 100644 > --- a/net/ipv4/sysctl_net_ipv4.c > +++ b/net/ipv4/sysctl_net_ipv4.c > @@ -47,6 +47,7 @@ static int tcp_syn_retries_max = MAX_TCP_SYNCNT; > static int ip_ping_group_range_min[] = { 0, 0 }; > static int ip_ping_group_range_max[] = { GID_T_MAX, GID_T_MAX }; > static int comp_sack_nr_max = 255; > +static int tcp_probe_interval_min = 300; > > /* obsolete */ > static int sysctl_tcp_low_latency __read_mostly; > @@ -711,7 +712,8 @@ static struct ctl_table ipv4_net_table[] = { > .data = &init_net.ipv4.sysctl_tcp_probe_interval, > .maxlen = sizeof(int), > .mode = 0644, > - .proc_handler = proc_dointvec, > + .proc_handler = proc_dointvec_minmax, > + .extra1 = &tcp_probe_interval_min, > }, > { > .procname = "igmp_link_local_mcast_reports", > Note that this change would stop people from being able to have packetdrill tests which would run in a reasonable amount of time. I do not believe linux kernel must enforce such a limit. It is up to the admin to set a value here really, depending on the environment the host is running in.