Quoting Ashley Pittman <ash...@pittman.co.uk>:
On 10 Apr 2010, at 04:51, Eugene Loh wrote:
Why is shared-memory performance about four orders of magnitude
slower than it should be? The processes are communicating via
memory that's shared by having the processes all mmap the same file
into their address spaces. Is it possible that with the newer
kernels, operations to that shared file are going all the way out
to disk? Maybe you don't know the answer, but hopefully someone on
this mail list can provide some insight.
Is the /tmp filesystem on NFS by any chance?
Yes, /tmp is on NFS .. those are diskless nodes all without disks and
no swap space mounted.
Maybe I should setup one of the nodes with a disk, so I could try the
difference.
(Sorry, but I may return results next week since, I am out of office
right now)
Thanks
oli
Ashley,
--
Ashley Pittman, Bath, UK.
Padb - A parallel job inspection tool for cluster computing
http://padb.pittman.org.uk
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