Bart,
  Each process is single threaded, although each process is built with the 
-lpthread library.  For this particular application I would expect the 
bottleneck to be in I/O (between processes) bound.  I hadn't thought 
about trying to boot YDL4 using the new kernel, I'll try that, and I'll
look at the lmench2 and interbench.  Thanks....

Rob



-----Original Message-----
From: Bart Van Assche [mailto:bart.vanassche@gmail.com]
Sent: Tue 3/25/2008 9:25 AM
To: Sanders, Rob M.
Cc: linux-kernel@vger.kernel.org
Subject: Re: Performance changes between 2.6.13 and 2.6.23
 
On Tue, Mar 25, 2008 at 1:34 PM, Sanders, Rob M. <sanders-rob@zai.com> wrote:
quoted text
>  Of more particular concern, the main application that I build has seen a 4-5X
> slowdown in performance.

Is this a singlethreaded or a multithreaded application ? Is this
application CPU-bound or IO-bound ? Does it rely a lot on memory
allocation ?

I'm not sure this will tell you the cause, but what might help is to
compile and run lmbench2 and interbench, and to compare the results
for the two kernel versions. Make sure that only the kernel version
differs between the two test runs, and that all other components (a.o.
libc and libpthread) stay the same. Booting the old YDL with the new
kernel should work, while booting the new YDL with an old kernel
probably will cause trouble.

See also http://www.bitmover.com/lmbench/ and
http://members.optusnet.com.au/ckolivas/interbench/.

Bart.

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