Date: Thu, 22 Dec 2005 13:23:29 +0200 From: Danny Braniss <danny@cs.huji.ac.il> To: Gleb Smirnoff <glebius@FreeBSD.org> Cc: freebsd-stable@FreeBSD.org Subject: Re: em bad performance Message-ID: <E1EpOXh-000Jxl-U9@cs1.cs.huji.ac.il> In-Reply-To: Message from Gleb Smirnoff <glebius@FreeBSD.org> of "Thu, 22 Dec 2005 13:52:15 %2B0300." <20051222105215.GB41381@cell.sick.ru>
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> On Thu, Dec 22, 2005 at 12:37:53PM +0200, Danny Braniss wrote: > D> > On Thu, Dec 22, 2005 at 12:24:42PM +0200, Danny Braniss wrote: > D> > D> ------------------------------------------------------------ > D> > D> Server listening on TCP port 5001 > D> > D> TCP window size: 64.0 KByte (default) > D> > D> ------------------------------------------------------------ > D> > D> [ 4] local 132.65.16.100 port 5001 connected with [6.0/SE7501WV2] port 58122 > D> > D> (intel westvill) > D> > D> [ ID] Interval Transfer Bandwidth > D> > D> [ 4] 0.0-10.0 sec 1.01 GBytes 867 Mbits/sec > D> > D> [ 4] local 132.65.16.100 port 5001 connected with [5.4/SE7501WV2] port 55269 > D> > D> (intel westvill) > D> > D> [ ID] Interval Transfer Bandwidth > D> > D> [ 4] 0.0-10.0 sec 967 MBytes 811 Mbits/sec > D> > D> [ 5] local 132.65.16.100 port 5001 connected with [6.0/SR1435VP2 port 58363 > D> > D> (intel dual xeon/emt64) > D> > D> [ ID] Interval Transfer Bandwidth > D> > D> [ 5] 0.0-10.0 sec 578 MBytes 485 Mbits/sec > D> > D> > D> > D> i've run this several times, and the results are very similar. > D> > D> i also tried i386, and the same bad results. > D> > D> all hosts are connected at 1gb to the same switch. > D> > > D> > So we see a strong drawback between SE7501WV2 and SR1435VP2. Let's compare the NIC > D> > hardware. Can you plese show pciconf -lv | grep -A3 ^em on both motherboards? > D> > D> on a SE7501WV2: > D> em0@pci3:7:0: class=0x020000 card=0x341a8086 chip=0x10108086 rev=0x01 > D> hdr=0x00 > D> vendor = 'Intel Corporation' > D> device = '82546EB Dual Port Gigabit Ethernet Controller (Copper)' > D> class = network > D> > D> on a SR1435VP2: > D> em0@pci4:3:0: class=0x020000 card=0x34668086 chip=0x10768086 rev=0x05 > D> hdr=0x00 > D> vendor = 'Intel Corporation' > D> device = '82547EI Gigabit Ethernet Controller' > D> class = network > > The first one 82546EB is attached to fast PCI-X bus, and the 82547EI is > on CSA bus. The CSA bus is twice faster than old PCI bus, CSA can handle > 266 Mbps. I'm not sure but may be it has same ~50% overhead as old PCI bus. > > Probably our em(4) driver is not optimized enough and does too many accesses > to the PCI bus, thus utilizing more bandwidth than needed to handle traffic. > In this case we see that NIC on slower bus (but enough to handle Gigabit) is > must slower than NIC on faster bus. (This paragraph is my own theory, it > can be complete bullshit.) humph, alway read the small letters: from Intel Server Board SE7320VP2 TPC: ... The device interfaces with the 6300ESB ICH from the 32-bit PCI 2.3 compliant bus running at 33MHz. so now is back to waiting for Yukon driver from Marvell, which is supposed to come out RSN. thanks, danny
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