bahman/scylla
1
0
Fork 0
Code Issues Pull Requests Actions 3 Packages Projects Releases Wiki Activity

tablet_allocator: load_balancer: table_size_desc: keep target_tablet_size as member

Browse Source 
Rather than target_max_tablet_size.  We need both the target
as well as max and min tablet sizes, so there is no sense
in keeping the max and deriving the target and the minimum
for the max value.

Signed-off-by: Benny Halevy <bhalevy@scylladb.com>
This commit is contained in:
Benny Halevy
2025-01-14 17:09:03 +02:00
parent 32c2f7579f
commit 559f083dc6
1 changed files with 11 additions and 14 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
service/tablet_allocator.cc
View File

@@ -479,22 +479,19 @@ class load_balancer {
// due to the average size dropping below the merge threshold, as tablet count doubles.
const uint64_t _target_tablet_size = default_target_tablet_size;
static constexpr uint64_t target_max_tablet_size(uint64_t target_tablet_size) {
return target_tablet_size * 2;
}
static constexpr uint64_t target_min_tablet_size(uint64_t max_tablet_size) {
return double(max_tablet_size / 2) * 0.5;
}
struct table_size_desc {
uint64_t target_max_tablet_size;
uint64_t target_tablet_size;
uint64_t avg_tablet_size;
locator::resize_decision resize_decision;
size_t tablet_count;
size_t shard_count;
uint64_t target_max_tablet_size() const noexcept {
return target_tablet_size * 2;
}
uint64_t target_min_tablet_size() const noexcept {
return load_balancer::target_min_tablet_size(target_max_tablet_size);
return target_tablet_size / 2;
}
};
@@ -516,7 +513,7 @@ class load_balancer {
return left_growing_mode && d.tablet_count > 1 && d.avg_tablet_size < d.target_min_tablet_size();
}
static bool table_needs_split(const table_size_desc& d) {
return d.avg_tablet_size > d.target_max_tablet_size;
return d.avg_tablet_size > d.target_max_tablet_size();
}
bool table_needs_resize(const table_size_desc& d) const {
@@ -531,9 +528,9 @@ class load_balancer {
bool table_needs_resize_cancellation(const table_size_desc& d) const {
auto& way = d.resize_decision.way;
if (std::holds_alternative<locator::resize_decision::split>(way)) {
return d.avg_tablet_size < d.target_max_tablet_size / 2;
return d.avg_tablet_size < d.target_tablet_size;
} else if (std::holds_alternative<locator::resize_decision::merge>(way)) {
return d.avg_tablet_size > d.target_min_tablet_size() * 2;
return d.avg_tablet_size > d.target_tablet_size;
}
return false;
}
@@ -560,7 +557,7 @@ class load_balancer {
return [] (const table_id_and_size_desc& a, const table_id_and_size_desc& b) {
auto urgency = [] (const table_size_desc& d) -> double {
// FIXME: only takes into account split today.
return double(d.avg_tablet_size) / d.target_max_tablet_size;
return double(d.avg_tablet_size) / d.target_max_tablet_size();
};
return urgency(a.second) < urgency(b.second);
};
@@ -1083,7 +1080,7 @@ public:
});
table_size_desc size_desc {
.target_max_tablet_size = target_max_tablet_size(_target_tablet_size),
.target_tablet_size = _target_tablet_size,
.avg_tablet_size = avg_tablet_size,
.resize_decision = tmap.resize_decision(),
.tablet_count = tmap.tablet_count(),