From mboxrd@z Thu Jan 1 00:00:00 1970 From: stephen@networkplumber.org (Stephen Hemminger) Date: Mon, 18 Nov 2013 08:54:07 -0800 Subject: [BUG,REGRESSION?] 3.11.6+,3.12: GbE iface rate drops to few KB/s In-Reply-To: <20131118104448.GI16823@kw.sim.vm.gnt> References: <8761s0cqhh.fsf@natisbad.org> <87y54u59zq.fsf@natisbad.org> <20131112083633.GB10318@1wt.eu> <87a9hagex1.fsf@natisbad.org> <20131112100126.GB23981@1wt.eu> <87vbzxd473.fsf@natisbad.org> <20131113072257.GB10591@1wt.eu> <20131117141940.GA18569@1wt.eu> <20131118112601.65feb708@skate> <20131118104448.GI16823@kw.sim.vm.gnt> Message-ID: <20131118085407.25dadcaf@samsung-9> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 18 Nov 2013 11:44:48 +0100 Simon Guinot wrote: > On Mon, Nov 18, 2013 at 11:26:01AM +0100, Thomas Petazzoni wrote: > > Willy, All, > > > > On Sun, 17 Nov 2013 15:19:40 +0100, Willy Tarreau wrote: > > > > > On Wed, Nov 13, 2013 at 08:22:57AM +0100, Willy Tarreau wrote: > > > > On Tue, Nov 12, 2013 at 04:34:24PM +0100, Arnaud Ebalard wrote: > > > > > Can you give a pre-3.11.7 kernel a try if you find the time? I > > > > > started working on RN102 during 3.10-rc cycle but do not remember > > > > > if I did the first preformance tests on 3.10 or 3.11. And if you > > > > > find more time, 3.11.7 would be nice too ;-) > > > > > > > > Still have not found time for this but I observed something > > > > intriguing which might possibly match your experience : if I use > > > > large enough send buffers on the mirabox and receive buffers on the > > > > client, then the traffic drops for objects larger than 1 MB. I have > > > > quickly checked what's happening and it's just that there are > > > > pauses of up to 8 ms between some packets when the TCP send window > > > > grows larger than about 200 kB. And since there are no drops, there > > > > is no reason for the window to shrink. I suspect it's exactly > > > > related to the issue explained by Eric about the timer used to > > > > recycle the Tx descriptors. However last time I checked, these ones > > > > were also processed in the Rx path, which means that the ACKs that > > > > flow back should have had the same effect as a Tx IRQ (unless I'd > > > > use asymmetric routing, which was not the case). So there might be > > > > another issue. Ah, and it only happens with GSO. > > > > I haven't read the entire discussion yet, but do you guys have > > http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/drivers/clk/mvebu?id=1022c75f5abd3a3b25e679bc8793d21bedd009b4 > > applied? It got merged recently, and it fixes a number of networking > > problems on Armada 370. > > > > I've added Simon Guinot in Cc, who is the author of this patch. > > I don't think it is related. We also have noticed a huge performance > regression. Reverting the following patch restores the rate: > > c9eeec26 tcp: TSQ can use a dynamic limit > But without that patch there was a performance regression for high speed interfaces whihc was caused by TSQ. 10G performance dropped to 8G