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cmd/utils: tune GOGC for large cache values

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This commit is contained in:
Sina Mahmoodi 2026-04-29 17:12:30 +02:00
parent 01036bed83
commit feea0dab16
1 changed files with 34 additions and 5 deletions
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39
cmd/utils/flags.go
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@ -1758,12 +1758,41 @@ func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *ethconfig.Config) {
ctx.Set(CacheFlag.Name, strconv.Itoa(allowance))
}
}
// Ensure Go's GC ignores the database cache for trigger percentage
// Tune Go's GC to balance throughput against the database cache.
//
// The historical formula here was:
// gogc = max(20, min(100, 100/(cache_GB)))
// which drove GOGC down to 20 at --cache >= 8 GiB. With GOGC=20, the GC
// fires every ~20% heap growth — and during block processing that
// burned ~20% of CPU on `runtime.scanobject`/`gcDrain`/`findObject`
// (confirmed by CPU profile of newPayload).
//
// Modern Go (1.19+) supports SetMemoryLimit, which lets the runtime
// keep GOGC at the default 100 (fewer/larger collections) while still
// guaranteeing memory stays below a soft cap. We size the cap so it's
// large enough that GOGC=100 governs steady-state behavior, but the
// limit kicks in if real memory pressure appears.
cache := ctx.Int(CacheFlag.Name)
gogc := max(20, min(100, 100/(float64(cache)/1024)))
log.Debug("Sanitizing Go's GC trigger", "percent", int(gogc))
godebug.SetGCPercent(int(gogc))
var memLimit int64
if mem, memErr := gopsutil.VirtualMemory(); memErr == nil && mem.Total > 0 {
// Leave half the host memory for the OS / page cache / other
// processes; cap the rest at roughly 4× the configured DB cache
// to avoid runaway growth on machines with lots of RAM but a
// modest --cache.
halfHost := int64(mem.Total / 2)
fourCache := int64(cache) * 4 * 1024 * 1024
memLimit = min(halfHost, fourCache)
} else {
// Fallback when the host's total memory isn't reportable.
memLimit = int64(cache) * 4 * 1024 * 1024
}
if memLimit < int64(cache)*1024*1024*2 {
// Always allow at least 2× the cache so the cache itself fits.
memLimit = int64(cache) * 1024 * 1024 * 2
}
log.Debug("Setting Go memory limit", "MB", memLimit/1024/1024)
godebug.SetMemoryLimit(memLimit)
godebug.SetGCPercent(100)
if ctx.IsSet(SyncTargetFlag.Name) {
cfg.SyncMode = ethconfig.FullSync // dev sync target forces full sync