crush: add note about r in recursive choose
Reflects ceph.git commit 4551fee9ad89d0427ed865d766d0d44004d3e3e1. Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com>
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@ -514,6 +514,14 @@ static void crush_choose_indep(const struct crush_map *map,
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/* choose through intervening buckets */
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for (;;) {
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/* note: we base the choice on the position
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* even in the nested call. that means that
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* if the first layer chooses the same bucket
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* in a different position, we will tend to
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* choose a different item in that bucket.
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* this will involve more devices in data
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* movement and tend to distribute the load.
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*/
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r = rep;
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/* be careful */
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