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node: smooth oversized -dbcache warnings

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The oversized `-dbcache` warning currently switches from a fixed `450 MiB` threshold below `2 GiB` of RAM to `75%` of total RAM at `2 GiB`.
This creates a cliff where a small increase in RAM can raise the warning threshold to about `1536 MiB`.

Apply the `75%` factor only to RAM above a `2 GiB` reserve while keeping `DEFAULT_DB_CACHE` as the minimum threshold.
This removes the cliff: the threshold stays at the default until the percentage term exceeds it, then grows by `0.75 MiB` per additional MiB of RAM.

This also aligns better with the recently merged parallel input prevout fetcher which performs better with slightly lower dbcache memory.

Co-authored-by: Bortlesboat <Bortlesboat@users.noreply.github.com>
This commit is contained in:
Lőrinc
2026-04-30 14:36:53 +02:00
parent 81405fc7ab
commit d164a04342
2 changed files with 24 additions and 22 deletions
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6
src/node/caches.h
View File

@@ -8,6 +8,7 @@
#include <kernel/caches.h>
#include <util/byte_units.h>
#include <algorithm>
#include <cstddef>
#include <cstdint>
@@ -17,6 +18,8 @@ class ArgsManager;
static constexpr uint64_t MIN_DB_CACHE{4_MiB};
//! -dbcache default (bytes)
static constexpr uint64_t DEFAULT_DB_CACHE{DEFAULT_KERNEL_CACHE};
//! Reserved non-dbcache memory usage.
static constexpr uint64_t DBCACHE_WARNING_RESERVED_RAM{2_GiB};
namespace node {
uint64_t GetDefaultDBCache();
@@ -32,7 +35,8 @@ struct CacheSizes {
CacheSizes CalculateCacheSizes(const ArgsManager& args, size_t n_indexes = 0);
constexpr bool ShouldWarnOversizedDbCache(uint64_t dbcache, uint64_t total_ram) noexcept
{
const uint64_t cap{(total_ram < 2_GiB) ? DEFAULT_DB_CACHE : (total_ram / 100) * 75};
const uint64_t available_ram{total_ram > DBCACHE_WARNING_RESERVED_RAM ? total_ram - DBCACHE_WARNING_RESERVED_RAM : 0};
const uint64_t cap{std::max<uint64_t>(DEFAULT_DB_CACHE, (available_ram / 4) * 3)};
return dbcache > cap;
}

40
src/test/caches_tests.cpp
View File

@@ -7,36 +7,34 @@
#include <boost/test/unit_test.hpp>
#include <cstdint>
using namespace node;
namespace {
void CheckDbCacheWarnThreshold(uint64_t threshold, uint64_t total_ram)
{
BOOST_CHECK(!ShouldWarnOversizedDbCache(threshold, total_ram));
BOOST_CHECK( ShouldWarnOversizedDbCache(threshold + 1, total_ram));
}
} // namespace
BOOST_AUTO_TEST_SUITE(caches_tests)
BOOST_AUTO_TEST_CASE(oversized_dbcache_warning)
{
// memory restricted setup - cap is DEFAULT_DB_CACHE (450 MiB)
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/4_MiB, /*total_ram=*/1_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/512_MiB, /*total_ram=*/1_GiB)); // At cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/1500_MiB, /*total_ram=*/1_GiB)); // Over cap
BOOST_CHECK(!ShouldWarnOversizedDbCache(MIN_DB_CACHE, 1_GiB));
// 2 GiB RAM - cap is 75%
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/1500_MiB, /*total_ram=*/2_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/1600_MiB, /*total_ram=*/2_GiB)); // Over cap
// Below DBCACHE_WARNING_RESERVED_RAM the existing fixed default dominates.
CheckDbCacheWarnThreshold(DEFAULT_DB_CACHE, 1_GiB);
CheckDbCacheWarnThreshold(DEFAULT_DB_CACHE, DBCACHE_WARNING_RESERVED_RAM);
// 4 GiB RAM - cap is 75%
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/2500_MiB, /*total_ram=*/4_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/3500_MiB, /*total_ram=*/4_GiB)); // Over cap
// Above DBCACHE_WARNING_RESERVED_RAM the warning fires at 75% of the headroom.
CheckDbCacheWarnThreshold(((3_GiB - DBCACHE_WARNING_RESERVED_RAM) / 4) * 3, 3_GiB);
// 8 GiB RAM - cap is 75%
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/6000_MiB, /*total_ram=*/8_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/7000_MiB, /*total_ram=*/8_GiB)); // Over cap
// 16 GiB RAM - cap is 75%
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/10_GiB, /*total_ram=*/16_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/15_GiB, /*total_ram=*/16_GiB)); // Over cap
// 32 GiB RAM - cap is 75%
BOOST_CHECK(!ShouldWarnOversizedDbCache(/*dbcache=*/20_GiB, /*total_ram=*/32_GiB)); // Under cap
BOOST_CHECK( ShouldWarnOversizedDbCache(/*dbcache=*/30_GiB, /*total_ram=*/32_GiB)); // Over cap
for (const auto total_ram : {8_GiB, 16_GiB, 32_GiB}) {
CheckDbCacheWarnThreshold(((total_ram - DBCACHE_WARNING_RESERVED_RAM) / 4) * 3, total_ram);
}
}
BOOST_AUTO_TEST_SUITE_END()