Reduce RPC benchmark variance

PiperOrigin-RevId: 733360063
Change-Id: I774a5b42d8979ce1b3b984625f9aace52d801dfd

Author: andreas-abel

fleetbench/rpc/BUILD

@@ -91,11 +91,11 @@ cc_library(
         ":fleetbenchservice_grpc",
         ":generator_process",
         ":rpc_counters",
+        "//fleetbench/common",
         "//fleetbench/rpc/protos:combo",
         "//fleetbench/rpc/protos:response_Message_cc_proto",
         "@com_github_grpc_grpc//:grpc++",
         "@com_github_grpc_grpc//:grpc_security_base",
-        "@com_google_absl//absl/hash",
         "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/strings",
         "@com_google_absl//absl/strings:string_view",
@@ -191,6 +191,7 @@ cc_library(
         ":rpcperf",
         "//fleetbench:benchmark_main",
         "//fleetbench:dynamic_registrar",
+        "//fleetbench/common",
         "//fleetbench/rpc/protos:combo",
         "@com_google_absl//absl/log:check",
         "@com_google_absl//absl/strings",

fleetbench/rpc/grpc_server.cc

@@ -19,12 +19,12 @@
 #include <memory>
 #include <utility>
 
-#include "absl/hash/hash.h"
 #include "absl/log/check.h"
 #include "absl/strings/str_cat.h"
 #include "absl/strings/string_view.h"
 #include "absl/time/clock.h"
 #include "absl/time/time.h"
+#include "fleetbench/common/common.h"
 #include "fleetbench/rpc/fleetbenchservice.grpc.pb.h"
 #include "fleetbench/rpc/generator_process.h"
 #include "fleetbench/rpc/protos/combo.h"
@@ -49,7 +49,7 @@ class PerfCallback final
       ::grpc::CallbackServerContext* context,
       const fleetbench::rpc::RequestMessage* request,
       fleetbench::rpc::ResponseMessage* response) override {
-    *response = server_->Buffer(this);
+    *response = server_->Buffer();
 
     // Wait before the response if configured.
     server_->Delay();
@@ -102,10 +102,8 @@ void GRPCServer::Start(absl::string_view filepath,
   StartCallback(builder);
 }
 
-const fleetbench::rpc::ResponseMessage& GRPCServer::Buffer(
-    const void* ctx) const {
-  return message_buffers_[absl::Hash<const void*>()(ctx) %
-                          message_buffers_.size()];
+const fleetbench::rpc::ResponseMessage& GRPCServer::Buffer() const {
+  return message_buffers_[GetRNG()() % message_buffers_.size()];
 }
 
 void GRPCServer::Delay() {

fleetbench/rpc/grpc_server.h

@@ -57,7 +57,7 @@ class GRPCServer {
   void Start(absl::string_view filepath, grpc::ServerBuilder* builder);
 
   // Return a random ResponseMessage response proto
-  const fleetbench::rpc::ResponseMessage& Buffer(const void* ctx) const;
+  const fleetbench::rpc::ResponseMessage& Buffer() const;
 
   // Delay based on `delay_dist`
   void Delay();

fleetbench/rpc/rpcperf_benchmark.cc

@@ -21,6 +21,7 @@
 #include "absl/strings/string_view.h"
 #include "absl/synchronization/mutex.h"
 #include "benchmark/benchmark.h"
+#include "fleetbench/common/common.h"
 #include "fleetbench/dynamic_registrar.h"
 #include "fleetbench/rpc/grpc_client.h"
 #include "fleetbench/rpc/grpc_server.h"
@@ -30,6 +31,9 @@
 namespace fleetbench::rpc {
 
 void BM_Rpc(benchmark::State &state, absl::string_view program) {
+  // Make each benchmark repetition reproducible, if using a fixed seed.
+  Random::instance().Reset();
+
   CHECK(fleetbench::rpc::kPrograms->count(program))
       << "Invalid program name \"" << program << "\" provided to benchmark";