<br><font size=2 face="sans-serif">Where can we point our customers for
documentation? I found the old ROMIO user's guide on </font>
<br>
<br><a href=http://www.mcs.anl.gov/research/projects/romio/><font size=2 face="sans-serif">http://www.mcs.anl.gov/research/projects/romio/</font></a>
<br>
<br><font size=2 face="sans-serif">which has some discussion of hints.
Is there anything else available?</font>
<br><font size=2 face="sans-serif"><br>
Bob Cernohous: (T/L 553) 507-253-6093<br>
<br>
BobC@us.ibm.com<br>
IBM Rochester, Building 030-2(C335), Department 61L<br>
3605 Hwy 52 North, Rochester, MN 55901-7829<br>
<br>
> Chaos reigns within.<br>
> Reflect, repent, and reboot.<br>
> Order shall return.<br>
</font>
<br><font size=1 color=#800080 face="sans-serif">----- Forwarded by Bob
Cernohous/Rochester/IBM on 09/08/2009 12:48 PM -----</font>
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<td width=40%><font size=1 face="sans-serif"><b>Bob Cernohous/Rochester/IBM</b></font>
<p><font size=1 face="sans-serif">08/21/2009 12:09 PM</font>
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<div align=right><font size=1 face="sans-serif">To</font></div>
<td><font size=1 face="sans-serif">mpich2-dev@mcs.anl.gov</font>
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<div align=right><font size=1 face="sans-serif">cc</font></div>
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<div align=right><font size=1 face="sans-serif">Subject</font></div>
<td><font size=1 face="sans-serif">Re: [mpich2-dev] Another romio performance
question</font><a href=Notes://d27ml101/06256514004E9535/A81D2288A21CE049852563560058058D/8920D401242B20A186257619005B6B6B>Link</a></table>
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<br><tt><font size=2>mpich2-dev-bounces@mcs.anl.gov wrote on 08/21/2009
11:38:17 AM:<br>
> <br>
> When the workload is as you describe, ROMIO normally looks at the<br>
> accesses and if there is any overlap, it decides it would be better<br>
> served with independent access (in ad_write_coll.c there's a check
for<br>
> interleaved accesses). Contiguous data like your customer's
falls<br>
> under the non-interleaved category.<br>
> <br>
> However, on BlueGene, the romio_cb_read and romio_cb_write hints are<br>
> set to 'enable' instead of 'automatic'. This is usually the
right<br>
> thing, since aggregation works great on bluegene for workloads that<br>
> are non-overlapping, but also non-contiguous.<br>
</font></tt>
<br><tt><font size=2>Ok, so I tried hinting romio_cb_read/write to automatic
and it doesn't do the aggregation and performs much better. I like
that even better than hinting cb_buffer_size. </font></tt>
<br>
<br><tt><font size=2>I think we're ok. Like you said, we might want
to look at our defaults and selection logic eventually, but I think I'm
happy with my answer for now.</font></tt>
<br>
<br><tt><font size=2>Thanks</font></tt>
<br>
<br><tt><font size=2>Bob Cernohous: (T/L 553) 507-253-6093</font></tt>
<br>
<br><tt><font size=2>BobC@us.ibm.com</font></tt>
<br><tt><font size=2>IBM Rochester, Building 030-2(C335), Department 61L</font></tt>
<br><tt><font size=2>3605 Hwy 52 North, Rochester, MN 55901-7829</font></tt>
<br>
<br><tt><font size=2>> Chaos reigns within.</font></tt>
<br><tt><font size=2>> Reflect, repent, and reboot.</font></tt>
<br><tt><font size=2>> Order shall return.</font></tt>
<br>