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author | Ilya Dryomov <ilya.dryomov@inktank.com> | 2013-12-24 19:19:25 (GMT) |
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committer | Ilya Dryomov <ilya.dryomov@inktank.com> | 2013-12-31 18:32:17 (GMT) |
commit | 3102b0a5b4cd63acccac78ca541b73fe28b4faa6 (patch) | |
tree | 31b3a5f69f9304fe740ece82e9e06f3dd55645fc /net/ceph | |
parent | 9a3b490a20e06368c81d7a81506e99388e733379 (diff) | |
download | linux-3102b0a5b4cd63acccac78ca541b73fe28b4faa6.tar.xz |
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>
Diffstat (limited to 'net/ceph')
-rw-r--r-- | net/ceph/crush/mapper.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/net/ceph/crush/mapper.c b/net/ceph/crush/mapper.c index caeb106..77b7a73 100644 --- a/net/ceph/crush/mapper.c +++ b/net/ceph/crush/mapper.c @@ -514,6 +514,14 @@ static void crush_choose_indep(const struct crush_map *map, /* choose through intervening buckets */ for (;;) { + /* note: we base the choice on the position + * even in the nested call. that means that + * if the first layer chooses the same bucket + * in a different position, we will tend to + * choose a different item in that bucket. + * this will involve more devices in data + * movement and tend to distribute the load. + */ r = rep; /* be careful */ |