On Wed, 2008-10-22 at 08:35 -0700, Harry Edmon wrote:
I have a dual quad-core Xeon system running software (http://www.unidata.ucar.edu/software/ldm) that relays and processes weather data through RPC calls, keeping a queue of data in a memory mapped file. Up until 2.6.26 the system has run just fine (for example 220.127.116.11). But starting with 2.6.26 through 18.104.22.168 the system runs into a problem after approximately 24 hours. The symptom is that the processing slows down to a crawl. Using "top" I can see that the System time is up over 90%, with almost no User and Wait time. If I stop and restart the software, most of the time it gets better - but sometimes it takes a reboot to fix the problem. I have an identical system that does just processing and ingesting data from remote systems, and it does not have this problem. I have tried a number of different kernel configurations, but they all show the same problem.
I suspect a problem with SUNRPC. I notice that there were a large number of SUNRPC patches in 2.6.26. I am looking for suggestions on how to pin down which patches are causing the problem. Are there ways to figure where in the kernel the time is being spent? I am will to work on isolating the problem, but I need some suggestions on the best way to do it given the large number of SUNRPC patches in 2.6.26 and the fact that each experiment takes a day.
The kernel sunrpc interface is not exported to user land: the glibc code
uses its own, entirely separate implementation of sunrpc.
I cannot therefore see, how your application's RPC calls can be affected
by kernel sunrpc changes.