Ilya Dryomov e2b149cc4b crush: add chooseleaf_vary_r tunable ... The current crush_choose_firstn code will re-use the same 'r' value for the recursive call. That means that if we are hitting a collision or rejection for some reason (say, an OSD that is marked out) and need to retry, we will keep making the same (bad) choice in that recursive selection. Introduce a tunable that fixes that behavior by incorporating the parent 'r' value into the recursive starting point, so that a different path will be taken in subsequent placement attempts. Note that this was done from the get-go for the new crush_choose_indep algorithm. This was exposed by a user who was seeing PGs stuck in active+remapped after reweight-by-utilization because the up set mapped to a single OSD. Reflects ceph.git commit a8e6c9fbf88bad056dd05d3eb790e98a5e43451a. Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>		2014-04-04 21:07:26 -07:00
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crush.c	crush: factor out (trivial) crush_destroy_rule()	2013-12-31 20:32:11 +02:00
hash.c	ceph: factor out libceph from Ceph file system	2010-10-20 15:37:28 -07:00
mapper.c	crush: add chooseleaf_vary_r tunable	2014-04-04 21:07:26 -07:00