| 171 |
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|
| 172 |
|
#ifdef IS_MPI |
| 173 |
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|
| 174 |
+ |
/********************************************************************* |
| 175 |
+ |
* Documentation? You want DOCUMENTATION? |
| 176 |
+ |
* |
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+ |
* Why all the potatoes below? |
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+ |
* |
| 179 |
+ |
* To make a long story short, the original version of DumpWriter |
| 180 |
+ |
* worked in the most inefficient way possible. Node 0 would |
| 181 |
+ |
* poke each of the node for an individual atom's formatted data |
| 182 |
+ |
* as node 0 worked its way down the global index. This was particularly |
| 183 |
+ |
* inefficient since the method blocked all processors at every atom |
| 184 |
+ |
* (and did it twice!). |
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+ |
* |
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+ |
* An intermediate version of DumpWriter could be described from Node |
| 187 |
+ |
* zero's perspective as follows: |
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* |
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+ |
* 1) Have 100 of your friends stand in a circle. |
| 190 |
+ |
* 2) When you say go, have all of them start tossing potatoes at |
| 191 |
+ |
* you (one at a time). |
| 192 |
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* 3) Catch the potatoes. |
| 193 |
+ |
* |
| 194 |
+ |
* It was an improvement, but MPI has buffers and caches that could |
| 195 |
+ |
* best be described in this analogy as "potato nets", so there's no |
| 196 |
+ |
* need to block the processors atom-by-atom. |
| 197 |
+ |
* |
| 198 |
+ |
* This new and improved DumpWriter works in an even more efficient |
| 199 |
+ |
* way: |
| 200 |
+ |
* |
| 201 |
+ |
* 1) Have 100 of your friend stand in a circle. |
| 202 |
+ |
* 2) When you say go, have them start tossing 5-pound bags of |
| 203 |
+ |
* potatoes at you. |
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+ |
* 3) Once you've caught a friend's bag of potatoes, |
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* toss them a spud to let them know they can toss another bag. |
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+ |
* |
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+ |
* How's THAT for documentation? |
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+ |
* |
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+ |
*********************************************************************/ |
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+ |
|
| 211 |
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int *potatoes; |
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int myPotato; |
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|
