Re: NFS--mounted builddirs and detecting clock skew

[Bob Friesenhahn]

On Wed, 21 Nov 2007, Harlan Stenn wrote:
> A variety of problems can crop up if one is "doing things" in an
> NFS-mounted filesystem and there is clock skew between the local machine
> (NFS client box) and the machine that hosts the  actual filesystem (NFS
> server box).

I suggest that you check out some cool software called xntp which can 
help correct your clock skew problems.

> If I am running a configure script and there is a clock skew problem, I
> would want to know this ASAP beacuse if the clock skew is not
> deliberate, I want to fix it Right Away.

Which particular clock skew do you want to detect?

  * Clock skew to source directory
  * Clock skew to build directory
  * Clock skew to header files outside the source directory
  * Clock skew to libraries outside the build directory
  * Clock skew to temporary file directory (gasp!)
  * Clock skew due to filesystem with 1 second time resolution
  * Clock skew during build due to wandering clock
  * Clock skew to parallel build machine

All of these problems are possible.  Some issues are seen by GNU make 
and others are not.  When my clocks are a bit off I have noticed that 
GNU make sometimes intermittently complains due to the "wandering 
clock" problem.  If I am not imagining things, I have seen configure 
complain about clock problems before so perhaps there is already a 
sanity check in place.

Bob
======================================
Bob Friesenhahn
address@hidden, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/