MB-24055: Change ht_size to 47; ht_resize_interval to 1s 92/77892/7
authorDave Rigby <daver@couchbase.com>
Tue, 9 May 2017 13:48:02 +0000 (14:48 +0100)
committerDave Rigby <daver@couchbase.com>
Wed, 24 May 2017 08:07:16 +0000 (08:07 +0000)
To determine a good tradeoff between initial memory usage and
rebalance speed, the following tests were performed:

    ht_size     ht_resize_interval (sec)  Rebalance time (min)  Initial RSS (MB)
    3079 (default)  60 (default)       4.5                   74.4
    769             1                       3.8                   52.2
    193             1                         4.3                   47
    47             1                         4.1                   45.5
    13             1                         4.4                   45

Based on these results a ht_size of 47 (with resize_interval==1) has
been picked - this gives rebalance time as good as current; but with a
39% reduction in initial memory usage.

Change-Id: I329e18240bace9f4905e3eb0c4d59abd97dd8cd1
Reviewed-on: http://review.couchbase.org/77892
Reviewed-by: Jim Walker <jim@couchbase.com>
Reviewed-by: Manu Dhundi <manu@couchbase.com>
Tested-by: Build Bot <build@couchbase.com>
configuration.json

index f9e9f03..7be0290 100644 (file)
             "type": "size_t"
         },
         "ht_resize_interval": {
-            "default": "60",
+            "default": "1",
             "descr": "Interval in seconds to wait between HashtableResizerTask executions.",
             "type": "size_t"
         },
         "ht_size": {
-            "default": "3079",
+            "default": "47",
             "descr": "Initial number of slots in HashTable objects.",
             "type": "size_t"
         },