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Make layout optimization work in relative terms

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This commit is contained in:
Alex Auvolat 2022-03-17 16:42:10 +01:00
parent 2814d41842
commit 509d256c58
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GPG Key ID: 0E496D15096376BE
1 changed files with 14 additions and 9 deletions
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23
src/rpc/layout.rs
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@ -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!();