Date: Wed, 30 Aug 2006 11:45:01 -0700 From: "Jack Vogel" <jfvogel@gmail.com> To: "Danny Braniss" <danny@cs.huji.ac.il> Cc: freebsd-net@freebsd.org, freebsd-stable@freebsd.org Subject: Re: tcp/udp performance Message-ID: <2a41acea0608301145j7bbed961j33ce903a27d8963d@mail.gmail.com> In-Reply-To: <E1GIMNJ-0000Dd-QH@cs1.cs.huji.ac.il> References: <E1GIMNJ-0000Dd-QH@cs1.cs.huji.ac.il>
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On 8/30/06, Danny Braniss <danny@cs.huji.ac.il> wrote: > > ever since 6.1 I've seen fluctuations in the performance of > the em (Intel(R) PRO/1000 Gigabit Ethernet). > > motherboard OBN (On Board NIC) > ---------------- ------------------ > 1- Intel SE7501WV2S Intel 82546EB::2.1 > 2- Intel SE7320VP2D2 INTEL 82541 > 3- Sun Fire X4100 Server Intel(R) PRO/1000 > > test 1: writing to a NetApp filer via NFS/UDP > FreeBSD Linux > MegaBytes/sec > 1- Average: 18.48 32.61 > 2- Average: 15.69 35.72 > 3- Average: 16.61 29.69 > (interstingly, doing NFS/TCP instead of NFS/UDP shows an increase in speed of > around 60% on FreeBSD but none on Linux) > > test2: iperf using 1 as server: > FreeBSD(*) Linux > Mbits/sec > 1- 926 905 (this machine was busy) > 2- 545 798 > 3- 910 912 > *: did a 'sysctl net.inet.tcp.sendspace=65536' > > > So, it seems to me something is not that good in the UDP department, but > I can't find what to tweek. > > Any help? > > danny Have discussed this some internally, the best idea I've heard is that UDP is not giving us the interrupt rate that TCP would, so we end up not cleaning up as often, and thus descriptors might not be as quickly available.. Its just speculation at this point. Try this: the default is only to have 256 descriptors, try going for the MAX which is 4K. Cheers, Jack
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