[lwhatley.ctr@navo.hpc.mil: Re: [Pvfs2-developers] Re: [Pvfs2-users] PVFS2 on Infiniband]

[Nathan Poznick]

Thus spake Pete Wyckoff:
> lwhatley.ctr at navo.hpc.mil wrote on Mon, 05 Jun 2006 10:53 -0500:
> > Pete, I think you're on to something!  Adding the sched_yield() call to 
> > the BMI_ib_testcontext() function has sped things up tremendously.  In 
> > addition, pvfs2-server now only shows 10% CPU usage (and not for nearly 
> > as long as previously) in top when doing the pvfs2-mkdir command.

Of course, in 2.6 kernels, use of sched_yield() means that you may end
up sleeping a long time, and could be asking for trouble...

- The behavior of sched_yield() changed a lot.  A task that uses
  this system call should now expect to sleep for possibly a very
  long time.  Tasks that do not really desire to give up the
  processor for a while should probably not make heavy use of this
  function.  Unfortunately, some GUI programs (like Open Office)
  do make excessive use of this call and under load their
  performance is poor.  It seems this new 2.6 behavior is optimal
  but some user-space applications may need fixing.


-- 
Nathan Poznick <kraken at wang-fu.org>

As a man is said to have a right to his property, he may be equally
said to have a property in his rights. - James Madison

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