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authorOndrej Zajicek (work) <santiago@crfreenet.org>2019-02-09 15:53:16 +0100
committerOndrej Zajicek (work) <santiago@crfreenet.org>2019-02-09 15:53:16 +0100
commitcd16538fc91778e31f8241f62ee47056f099c051 (patch)
treee94474a81ff652c8d8d6d46722aac62043aa3770 /nest/rt-fib.c
parent6e8fb66859a17b295cd9246264221a75cdbe6c55 (diff)
parentf9b97f1c6282be398d2c2bb896dbb453f638f720 (diff)
Merge remote-tracking branch 'origin/mq-opt'
Diffstat (limited to 'nest/rt-fib.c')
-rw-r--r--nest/rt-fib.c47
1 files changed, 44 insertions, 3 deletions
diff --git a/nest/rt-fib.c b/nest/rt-fib.c
index 48091d43..a8800b65 100644
--- a/nest/rt-fib.c
+++ b/nest/rt-fib.c
@@ -58,11 +58,52 @@
#include "nest/route.h"
#include "lib/string.h"
+/*
+ * The FIB rehash values are maintaining FIB count between N/5 and 2N. What
+ * does it mean?
+ *
+ * +------------+--------+---------+-----------+----------+-----------+
+ * | Table size | Memory | Min cnt | net + rte | Max cnt | net + rte |
+ * +------------+--------+---------+-----------+----------+-----------+
+ * | 1k | 8k | 0 | 0 | 2k | 192 k |
+ * | 2k | 16k | 409 | 38.3k | 4k | 384 k |
+ * | 4k | 32k | 819 | 76.8k | 8k | 768 k |
+ * | 8k | 64k | 1.6k | 153.6k | 16k | 1.5M |
+ * | 16k | 128k | 3.2k | 307.1k | 32k | 3 M |
+ * | 32k | 256k | 6.4k | 614.3k | 64k | 6 M |
+ * | 64k | 512k | 12.8k | 1.2M | 128k | 12 M |
+ * | 128k | 1024k | 25.6k | 2.4M | 256k | 24 M |
+ * | 256k | 2M | 51.2k | 4.8M | 512k | 48 M |
+ * | 512k | 4M | 102.4k | 9.6M | 1M | 96 M |
+ * | 1M | 8M | 204.8k | 19.2M | 2M | 192 M |
+ * | 2M | 16M | 409.6k | 38.4M | 4M | 384 M |
+ * | 4M | 32M | 819.2k | 76.8M | 8M | 768 M |
+ * | 8M | 64M | 1.6M | 153.6M | infinity | infinity |
+ * +------------+--------+---------+-----------+----------+-----------+
+ *
+ * Table size shows how many slots are in FIB table.
+ * Memory shows how much memory is eaten by FIB table.
+ * Min cnt minimal number of nets in table of given size
+ * Max cnt maximal number of nets in table of given size
+ * net + rte memory eaten by 1 net and one route in it for min cnt and max cnt
+ *
+ * Example: If we have 750,000 network entries in a table:
+ * * the table size may be 512k if we have never had more
+ * * the table size may be 1M or 2M if we at least happened to have more
+ * * 256k is too small, 8M is too big
+ *
+ * When growing, rehash is done on demand so we do it on every power of 2.
+ * When shrinking, rehash is done on delete which is done (in global tables)
+ * in a scheduled event. Rehashing down 2 steps.
+ *
+ */
+
+
#define HASH_DEF_ORDER 10
-#define HASH_HI_MARK *4
-#define HASH_HI_STEP 2
+#define HASH_HI_MARK * 2
+#define HASH_HI_STEP 1
#define HASH_HI_MAX 24
-#define HASH_LO_MARK /5
+#define HASH_LO_MARK / 5
#define HASH_LO_STEP 2
#define HASH_LO_MIN 10