Messages in this thread | | | Date | Sat, 17 Jun 2006 16:23:34 -0700 | From | Harry Edmon <> | Subject | Re: Network performance degradation from 2.6.11.12 to 2.6.16.20 |
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I assume you are talking about using TCP_NODELAY as a socket option within the LDM software. I could give that a try.
There is a lot of traffic on this node, on the order of 2000 packets in and out per second, so the tcpdump output will grow pretty fast. How long a tcpdump would be useful, and what options would you suggest?
I should also note that my network interfaces are Intel, using the latest e1000 driver.
Andrew Morton wrote: > On Fri, 16 Jun 2006 09:01:23 -0700 > Harry Edmon <harry@atmos.washington.edu> wrote: > >> I have a system with a strange network performance degradation from >> 2.6.11.12 to most recent kernels including 2.6.16.20 and 2.6.17-rc6. >> The system is has Dual single core Xeons with hyperthreading on. The >> application is the LDM system from UCAR/Unidata >> (http://www.unidata.ucar.edu/software/ldm). This system requests >> weather data from a variety of systems using RPC calls over a reserved >> TCP port (388), puts them into a memory mapped queue file, and then >> sends the data out to a variety of downstream requesting systems, again >> using RPC calls. When the load is heavy, the 2.6.16.20 kernel falls way >> behind with the data ingestion. The 2.6.11.12 kernel does not. I have >> tried an experiment with a 2.6.17-rc6 system where it just does the >> ingestion, and not the downstream distribution, and it is able to keep >> up. I would really appreciate any pointers as to where the problem may >> be and how to diagnose it. I have attached the config files from both >> kernels and the sysctl.conf file I am using. I have also included the >> output from "netstat -s" on the 2.6.16.20 system during a time when it >> was having problems. >> > > (added netdev) > > A quick grep indicates that it isn't using TCP_NODELAY - we've had problems > with that in the past. > > Perhaps a tcpdump of the net traffic will help to determine what's going on.
-- Dr. Harry Edmon E-MAIL: harry@atmos.washington.edu 206-543-0547 harry@u.washington.edu Dept of Atmospheric Sciences FAX: 206-543-0308 University of Washington, Box 351640, Seattle, WA 98195-1640 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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