From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Subject: Re: [PATCH net] sctp: not allow to set rto_min with a value below 200 msecs Date: Tue, 29 May 2018 14:06:04 -0300 Message-ID: <20180529170604.GD3788@localhost.localdomain> References: <20180525191319.GB392@hmswarspite.think-freely.org> <71FD541D-25FE-4100-980B-C3A0CEAF6CD4@lurchi.franken.de> <20180527010059.GA15798@neilslaptop.think-freely.org> <20180528194315.GB3788@localhost.localdomain> <20180529114111.GA24144@hmswarspite.think-freely.org> <559FFFDD-E508-4936-9544-CACE606AF40F@lurchi.franken.de> <20180529154514.GC3788@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Michael Tuexen , nhorman@tuxdriver.com, Dmitry Vyukov , lucien.xin@gmail.com, Netdev , linux-sctp@vger.kernel.org, David Miller , dsa@cumulusnetworks.com, Eric Dumazet , syzkaller@googlegroups.com To: Neal Cardwell Return-path: Received: from mail-qt0-f175.google.com ([209.85.216.175]:37042 "EHLO mail-qt0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965154AbeE2RGK (ORCPT ); Tue, 29 May 2018 13:06:10 -0400 Content-Disposition: inline In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: On Tue, May 29, 2018 at 12:03:46PM -0400, Neal Cardwell wrote: > On Tue, May 29, 2018 at 11:45 AM Marcelo Ricardo Leitner < > marcelo.leitner@gmail.com> wrote: > > - patch2 - fix rtx attack vector > > - Add the floor value to rto_min to HZ/20 (which fits the values > > that Michael shared on the other email) > > I would encourage allowing minimum RTO values down to 5ms, if the ACK > policy in the receiver makes this feasible. Our experience is that in > datacenter environments it can be advantageous to allow timer-based loss > recoveries using timeout values as low as 5ms, e.g.: Thanks Neal. On Xin's tests, the hearbeat timer becomes an issue at ~25ms already. Xin, can you share more details on the hw, which CPU was used? Anyway, what about we add a floor to rto_max too, so that RTO can actually grow into something bigger that don't hog the CPU? Like: rto_min floor = 5ms rto_max floor = 50ms Marcelo From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Ricardo Leitner Date: Tue, 29 May 2018 17:06:04 +0000 Subject: Re: [PATCH net] sctp: not allow to set rto_min with a value below 200 msecs Message-Id: <20180529170604.GD3788@localhost.localdomain> List-Id: References: <20180525191319.GB392@hmswarspite.think-freely.org> <71FD541D-25FE-4100-980B-C3A0CEAF6CD4@lurchi.franken.de> <20180527010059.GA15798@neilslaptop.think-freely.org> <20180528194315.GB3788@localhost.localdomain> <20180529114111.GA24144@hmswarspite.think-freely.org> <559FFFDD-E508-4936-9544-CACE606AF40F@lurchi.franken.de> <20180529154514.GC3788@localhost.localdomain> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Neal Cardwell Cc: Michael Tuexen , nhorman@tuxdriver.com, Dmitry Vyukov , lucien.xin@gmail.com, Netdev , linux-sctp@vger.kernel.org, David Miller , dsa@cumulusnetworks.com, Eric Dumazet , syzkaller@googlegroups.com On Tue, May 29, 2018 at 12:03:46PM -0400, Neal Cardwell wrote: > On Tue, May 29, 2018 at 11:45 AM Marcelo Ricardo Leitner < > marcelo.leitner@gmail.com> wrote: > > - patch2 - fix rtx attack vector > > - Add the floor value to rto_min to HZ/20 (which fits the values > > that Michael shared on the other email) > > I would encourage allowing minimum RTO values down to 5ms, if the ACK > policy in the receiver makes this feasible. Our experience is that in > datacenter environments it can be advantageous to allow timer-based loss > recoveries using timeout values as low as 5ms, e.g.: Thanks Neal. On Xin's tests, the hearbeat timer becomes an issue at ~25ms already. Xin, can you share more details on the hw, which CPU was used? Anyway, what about we add a floor to rto_max too, so that RTO can actually grow into something bigger that don't hog the CPU? Like: rto_min floor = 5ms rto_max floor = 50ms Marcelo