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authorAlex Auvolat <alex@adnab.me>2022-03-17 16:42:10 +0100
committerAlex Auvolat <alex@adnab.me>2022-03-24 15:27:14 +0100
commit509d256c58ccb1aa0041569556465908453976b3 (patch)
tree73c5d5c5e2f2fdc4f9bf0db29483accf09660171
parent2814d41842bd48b0015c5ae000a61113b7d806d7 (diff)
downloadgarage-bug/layout.tar.gz
garage-bug/layout.zip
Make layout optimization work in relative termsbug/layout
-rw-r--r--src/rpc/layout.rs23
1 files changed, 14 insertions, 9 deletions
diff --git a/src/rpc/layout.rs b/src/rpc/layout.rs
index 73b356ad..b9c02c21 100644
--- a/src/rpc/layout.rs
+++ b/src/rpc/layout.rs
@@ -245,8 +245,13 @@ impl ClusterLayout {
let mut option = None;
for (i, part) in partitions.iter_mut().enumerate() {
for (irm, (idrm, _)) in part.nodes.iter().enumerate() {
- let suprm = partitions_per_node.get(*idrm).cloned().unwrap_or(0) as i32
- - target_partitions_per_node.get(*idrm).cloned().unwrap_or(0) as i32;
+ let errratio = |node, parts| {
+ let tgt = *target_partitions_per_node.get(node).unwrap() as f32;
+ (parts - tgt) / tgt
+ };
+ let square = |x| x * x;
+
+ let partsrm = partitions_per_node.get(*idrm).cloned().unwrap_or(0) as f32;
for (idadd, infoadd) in configured_nodes.iter() {
// skip replacing a node by itself
@@ -255,14 +260,12 @@ impl ClusterLayout {
continue;
}
- let supadd = partitions_per_node.get(*idadd).cloned().unwrap_or(0) as i32
- - target_partitions_per_node.get(*idadd).cloned().unwrap_or(0) as i32;
-
// We want to try replacing node idrm by node idadd
// if that brings us close to our goal.
- let square = |i: i32| i * i;
- let oldcost = square(suprm) + square(supadd);
- let newcost = square(suprm - 1) + square(supadd + 1);
+ let partsadd = partitions_per_node.get(*idadd).cloned().unwrap_or(0) as f32;
+ let oldcost = square(errratio(*idrm, partsrm) - errratio(*idadd, partsadd));
+ let newcost =
+ square(errratio(*idrm, partsrm - 1.) - errratio(*idadd, partsadd + 1.));
if newcost >= oldcost {
// not closer to our goal
continue;
@@ -315,7 +318,9 @@ impl ClusterLayout {
// Show statistics
println!("New number of partitions per node:");
for (node, npart) in partitions_per_node.iter() {
- println!("{:?}\t{}", node, npart);
+ let tgt = *target_partitions_per_node.get(node).unwrap();
+ let pct = 100f32 * (*npart as f32) / (tgt as f32);
+ println!("{:?}\t{}\t({}% of {})", node, npart, pct as i32, tgt);
}
println!();