diff --git a/pkg/sysfs/system.go b/pkg/sysfs/system.go index 53d280954..ddfb15a4a 100644 --- a/pkg/sysfs/system.go +++ b/pkg/sysfs/system.go @@ -15,6 +15,7 @@ package sysfs import ( + "encoding/json" "errors" "fmt" "io/fs" @@ -277,6 +278,8 @@ var ( PerformanceCore: "OVERRIDE_SYS_CORE_CPUS", EfficientCore: "OVERRIDE_SYS_ATOM_CPUS", } + cacheEnvOverridesVar = "OVERRIDE_SYS_CACHES" + cacheEnvOverridesJson = os.Getenv(cacheEnvOverridesVar) ) // MemInfo contains data read from a NUMA node meminfo file. @@ -306,6 +309,21 @@ type Cache struct { cpus idset.IDSet // CPUs sharing this cache } +// cacheOverrides is a list of cache overrides for specific CPU sets. +// Every CPU set gets cache id that starts from 0 on each override object. +// Example: two 128 MB L3 Caches shared by CPUs 0-15,32-47 (socket 0) +// and 16-31,48-63 (socket 1). The cache id is 0 for the first, 1 for the second. +// [{"cpusets": ["0-15,32-47", "16-31,48-63"], "level": 3, "size": "128M"}] +type cacheOverrides []cacheOverride +type cacheOverride struct { + Cpusets []string // cpusets to which this override applies + Level int // cache level + Kind string // "d" for data, "i" for instruction, "u" for unified + Size string // cache size, e.g. "4M" +} + +var cacheEnvOverrides = parseCpuCacheOverrides(cacheEnvOverridesJson) + // SetSysRoot sets the sys root directory. func SetSysRoot(root string) { if root != "" { @@ -934,17 +952,27 @@ func (sys *system) discoverCPU(path string) error { } if (sys.flags & DiscoverCache) != 0 { - entries, _ := filepath.Glob(filepath.Join(path, "cache/index[0-9]*")) - slices.SortFunc(entries, func(a, b string) int { - a = strings.TrimPrefix(filepath.Base(a), "index") - b = strings.TrimPrefix(filepath.Base(b), "index") - idxA, _ := strconv.Atoi(a) - idxB, _ := strconv.Atoi(b) - return idxA - idxB - }) - for _, entry := range entries { - if err := sys.discoverCache(cpu, entry); err != nil { - return err + if caches, ok := cacheEnvOverrides[cpu.id]; ok { + // we have cache overrides for this CPU, apply them + cpu.caches = make([]*Cache, len(caches)) + for i, c := range caches { + log.Debugf("cpu %d cache override %+v", cpu.id, *c) + cpu.caches[i] = sys.saveCache(c) + } + } else { + // discover caches for this CPU from sysfs + entries, _ := filepath.Glob(filepath.Join(path, "cache/index[0-9]*")) + slices.SortFunc(entries, func(a, b string) int { + a = strings.TrimPrefix(filepath.Base(a), "index") + b = strings.TrimPrefix(filepath.Base(b), "index") + idxA, _ := strconv.Atoi(a) + idxB, _ := strconv.Atoi(b) + return idxA - idxB + }) + for _, entry := range entries { + if err := sys.discoverCache(cpu, entry); err != nil { + return err + } } } } @@ -1526,6 +1554,88 @@ func (sys *system) discoverSst() error { return nil } +func parseSize(s string) (uint64, error) { + var size uint64 + var unit string + if _, err := fmt.Sscanf(s, "%d%s", &size, &unit); err != nil { + if _, err := fmt.Sscanf(s, "%d", &size); err != nil { + return 0, err + } + } + switch unit { + case "k", "K", "KB": + size *= 1 << 10 + case "M", "MB": + size *= 1 << 20 + case "G", "GB": + size *= 1 << 30 + case "T", "TB": + size *= 1 << 40 + case "": + default: + return 0, fmt.Errorf("unknown unit %q", unit) + } + return size, nil +} + +// Parse cache overrides from a JSON string. +func parseCpuCacheOverrides(overrideJson string) map[int][]*Cache { + if overrideJson == "" { + return nil + } + logCcoError := func(format string, args ...interface{}) { + log.Error("CPU cache override: "+format, args...) + } + cpuCacheOverrides := make(map[int][]*Cache) + overrides := cacheOverrides{} + if err := json.Unmarshal([]byte(overrideJson), &overrides); err != nil { + logCcoError("unmarshaling %q failed: %v", overrideJson, err) + return nil + } + for _, override := range overrides { + nextId := 0 + for _, cpusetStr := range override.Cpusets { + cpusCpuset, err := cpuset.Parse(cpusetStr) + if err != nil { + logCcoError("parsing cpuset %q failed: %v\n", cpusetStr, err) + continue + } + cpus := idset.NewIDSet(cpusCpuset.UnsortedList()...) + c := &Cache{ + id: idset.ID(nextId), + } + nextId++ + switch strings.ToLower(override.Kind) { + case "d", "data": + c.kind = DataCache + case "i", "instruction": + c.kind = InstructionCache + case "u", "unified", "": + c.kind = UnifiedCache + default: + logCcoError("unknown cache kind %q\n", override.Kind) + continue + } + if override.Level > 0 { + c.level = override.Level + } else { + c.level = 1 + } + c.size, err = parseSize(override.Size) + if err != nil { + logCcoError("parsing size %q failed: %v\n", override.Size, err) + continue + } + c.cpus = cpus + for _, cpu := range cpus.Members() { + cpuCacheOverrides[cpu] = append(cpuCacheOverrides[cpu], c) + } + log.Debugf("override cache: %+v", *c) + } + } + return cpuCacheOverrides +} + // ID returns the id of this package. func (p *cpuPackage) ID() idset.ID { return p.id