Memory optimizations

Do not cache large objects like the BTF and ksyms. Reload them when needed. Signed-off-by: Anastasios Papagiannis <[email protected]>
cilium · Sep 19, 2024 · 1c61893 · 1c61893
1 parent c35738c
commit 1c61893
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Showing 3 changed files with 10 additions and 11 deletions.
diff --git a/pkg/bpf/detect.go b/pkg/bpf/detect.go
@@ -422,6 +422,10 @@ func HasMissedStatsKprobeMulti() bool {
 }
 
 func LogFeatures() string {
+	// once we have detected all features, flush the BTF spec
+	// we cache all values so calling again a Has* function will
+	// not load the BTF again
+	defer ebtf.FlushKernelSpec()
 	return fmt.Sprintf("override_return: %t, buildid: %t, kprobe_multi: %t, uprobe_multi %t, fmodret: %t, fmodret_syscall: %t, signal: %t, large: %t, link_pin: %t, lsm: %t, missed_stats_kprobe_multi: %t, missed_stats_kprobe: %t",
 		HasOverrideHelper(), HasBuildId(), HasKprobeMulti(), HasUprobeMulti(),
 		HasModifyReturn(), HasModifyReturnSyscall(), HasSignalHelper(), HasProgramLargeSize(),

diff --git a/pkg/ksyms/ksyms.go b/pkg/ksyms/ksyms.go
@@ -11,25 +11,15 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
 
 	"github.com/cilium/tetragon/pkg/logger"
 	"github.com/cilium/tetragon/pkg/option"
 
 	lru "github.com/hashicorp/golang-lru/v2"
 )
 
-var (
-	kernelSymbols    *Ksyms
-	setKernelSymbols sync.Once
-)
-
 func KernelSymbols() (*Ksyms, error) {
-	var err error
-	setKernelSymbols.Do(func() {
-		kernelSymbols, err = NewKsyms(option.Config.ProcFS)
-	})
-	return kernelSymbols, err
+	return NewKsyms(option.Config.ProcFS)
 }
 
 type ksym struct {

diff --git a/pkg/sensors/program/loader.go b/pkg/sensors/program/loader.go
@@ -856,6 +856,8 @@ func doLoadProgram(
 		return nil, fmt.Errorf("opening collection '%s' failed: %w", load.Name, err)
 	}
 	defer coll.Close()
+	// cleanup the BTF once we have loaded the program
+	defer btf.FlushKernelSpec()
 
 	err = installTailCalls(bpfDir, spec, coll, load)
 	if err != nil {
@@ -911,6 +913,9 @@ func doLoadProgram(
 
 	load.Prog = prog
 
+	// now we don't need the BTF anymore
+	load.KernelTypes = nil
+
 	// Copy the loaded collection before it's destroyed
 	if KeepCollection {
 		return copyLoadedCollection(coll)