preallocate CPU usage - pre4

Rob Bosch
Mon, 05 Nov 2007 13:25:41 -0000

When I use the preallocate patch and create a 77GB file using the function I
get a CPU spike on the server-side.  The spike lasts about 20 minutes and
uses about 20%-25% of the cpu associated with the rsync instance creating
the file.  The spike is directly linked to the time it takes to create the
file.

I compiled rsync using cygwin CVS.  I initially suspected the implementation
of posix_fallocate in cygwin.  I posted the same question to their board and
Corinna indicated she can create a 40GB file in a few milliseconds.  I'm
wondering if there is something else going on at this point.

Does anyone else get this issue too?  I want to confirm it isn't just a
problem with my environment.  I've replicated it on machines but they are
all using the same cygwin build I created.  It would be great to get a
confirmation (positive or negative) from someone running it under Linux.

The preallocate is working, it just is taking a while to create the file.

Rob