Quoting Ashley Pittman <ashley_at_[hidden]>:
>
> 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
>
>
> _______________________________________________
> devel mailing list
> devel_at_[hidden]
> http://www.open-mpi.org/mailman/listinfo.cgi/devel
>
> --
> This message has been scanned for viruses and
> dangerous content by MailScanner, and is
> believed to be clean.
>
>
----------------------------------------------------------------
This message was sent using IMP, the Internet Messaging Program.
--
This message has been scanned for viruses and
dangerous content by MailScanner, and is
believed to be clean.
|
![[Flag]](../../../../../community/mirrors/flag-us.gif){kind=small}