Re: SUNRPC problem with 2.6.26 and beyond

From: Trond Myklebust
Date: Wed Oct 22 2008 - 18:51:28 EST

On Wed, 2008-10-22 at 08:35 -0700, Harry Edmon wrote:
> I have a dual quad-core Xeon system running software
> ( 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
> But starting with 2.6.26 through 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.


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