[OpenAFS] afs.GCPAGs in current releases under Linux (RHEL4/5)

[Eric.Hagberg@morganstanley.com]

On Fri, 5 Mar 2010, Simon Wilkinson wrote:

> Things are quite different in 1.5 - keyrings are the authoritative
> source of PAG information. If you have time, it would be great if you
> could do the same tests with 1.5, and see if you experience similar
> problems.

This took a little longer to set up than I'd hoped, as 1.5.72 doesn't work 
under RHEL4 (the platform on which I was doing most of my tests), due to 
the lack of zero_user_segments and page_offset in the compiled kernel 
module.

However, the results running 1.5.72 on a RHEL5 system are pretty much the 
same as with 1.4.x (where x is greater than or equal to 2), wrt system 
time creep.

One thing I'd noticed in RHEL4 tests (systemtap doesn't seem to give the 
same result under RHEL5) is that the system time usage corresponds to high 
frequencies of calling afs_ComputePAGStats. Compiling with AFS_NOSTATS 
defined or commenting out the section of code in src/afs/afs_user.c that 
calls afs_ComputePAGStats also relieves the problem.