[resource_quota] Periodically return memory to central quota (#30268)

* [resource_quota] Periodically return memory to central quota * Automated change: Fix sanity tests * Automated change: Fix sanity tests * optionalize features * fix periodic update behavior around initialization * fix * fix * fix Co-authored-by: ctiller <ctiller@users.noreply.github.com>
2 years ago · 6fc2511e4d
parent a1d42f84ef
commit 6fc2511e4d
18 changed files with 101 additions and 14 deletions
--- a/2
+++ b/2
@ -1860,11 +1860,13 @@ grpc_cc_library(
        "loop",
        "map",
        "orphanable",
        "periodic_update",
        "poll",
        "race",
        "ref_counted_ptr",
        "resource_quota_trace",
        "seq",
        "time",
        "useful",
    ],
 )
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -2184,6 +2184,7 @@ add_library(grpc
  src/core/lib/resource_quota/api.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -2810,6 +2811,7 @@ add_library(grpc_unsecure
  src/core/lib/resource_quota/api.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -5959,6 +5961,7 @@ add_executable(arena_promise_test
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -7587,6 +7590,7 @@ add_executable(chunked_vector_test
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -9782,6 +9786,7 @@ add_executable(flow_control_test
  src/core/lib/iomgr/iomgr_internal.cc
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -9847,6 +9852,7 @@ add_executable(for_each_test
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -12724,6 +12730,7 @@ if(_gRPC_PLATFORM_LINUX OR _gRPC_PLATFORM_POSIX)
    src/core/lib/iomgr/iomgr_internal.cc
    src/core/lib/promise/activity.cc
    src/core/lib/resource_quota/memory_quota.cc
    src/core/lib/resource_quota/periodic_update.cc
    src/core/lib/resource_quota/trace.cc
    src/core/lib/slice/percent_encoding.cc
    src/core/lib/slice/slice.cc
@ -12784,6 +12791,7 @@ add_executable(memory_quota_test
  src/core/lib/iomgr/iomgr_internal.cc
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/trace.cc
  src/core/lib/slice/percent_encoding.cc
  src/core/lib/slice/slice.cc
@ -13821,6 +13829,7 @@ add_executable(pipe_test
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/arena.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
@ -14678,6 +14687,7 @@ add_executable(resource_quota_test
  src/core/lib/iomgr/iomgr_internal.cc
  src/core/lib/promise/activity.cc
  src/core/lib/resource_quota/memory_quota.cc
  src/core/lib/resource_quota/periodic_update.cc
  src/core/lib/resource_quota/resource_quota.cc
  src/core/lib/resource_quota/thread_quota.cc
  src/core/lib/resource_quota/trace.cc
--- a/2
+++ b/2
@ -1557,6 +1557,7 @@ LIBGRPC_SRC = \
    src/core/lib/resource_quota/api.cc \
    src/core/lib/resource_quota/arena.cc \
    src/core/lib/resource_quota/memory_quota.cc \
    src/core/lib/resource_quota/periodic_update.cc \
    src/core/lib/resource_quota/resource_quota.cc \
    src/core/lib/resource_quota/thread_quota.cc \
    src/core/lib/resource_quota/trace.cc \
@ -2022,6 +2023,7 @@ LIBGRPC_UNSECURE_SRC = \
    src/core/lib/resource_quota/api.cc \
    src/core/lib/resource_quota/arena.cc \
    src/core/lib/resource_quota/memory_quota.cc \
    src/core/lib/resource_quota/periodic_update.cc \
    src/core/lib/resource_quota/resource_quota.cc \
    src/core/lib/resource_quota/thread_quota.cc \
    src/core/lib/resource_quota/trace.cc \
--- a/build_autogenerated.yaml
+++ b/build_autogenerated.yaml
@ -873,6 +873,7 @@ libs:
  - src/core/lib/resource_quota/api.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -1539,6 +1540,7 @@ libs:
  - src/core/lib/resource_quota/api.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -2090,6 +2092,7 @@ libs:
  - src/core/lib/resource_quota/api.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -2397,6 +2400,7 @@ libs:
  - src/core/lib/resource_quota/api.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -3922,6 +3926,7 @@ targets:
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -3947,6 +3952,7 @@ targets:
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -4551,6 +4557,7 @@ targets:
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -4575,6 +4582,7 @@ targets:
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -5481,6 +5489,7 @@ targets:
  - src/core/lib/promise/race.h
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -5507,6 +5516,7 @@ targets:
  - src/core/lib/iomgr/iomgr_internal.cc
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -5571,6 +5581,7 @@ targets:
  - src/core/lib/promise/wait_set.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -5596,6 +5607,7 @@ targets:
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -6638,6 +6650,7 @@ targets:
  - src/core/lib/promise/race.h
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/trace.h
  - src/core/lib/slice/percent_encoding.h
  - src/core/lib/slice/slice.h
@ -6659,6 +6672,7 @@ targets:
  - src/core/lib/iomgr/iomgr_internal.cc
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/trace.cc
  - src/core/lib/slice/percent_encoding.cc
  - src/core/lib/slice/slice.cc
@ -6712,6 +6726,7 @@ targets:
  - src/core/lib/promise/race.h
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/trace.h
  - src/core/lib/slice/percent_encoding.h
  - src/core/lib/slice/slice.h
@ -6734,6 +6749,7 @@ targets:
  - src/core/lib/iomgr/iomgr_internal.cc
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/trace.cc
  - src/core/lib/slice/percent_encoding.cc
  - src/core/lib/slice/slice.cc
@ -7200,6 +7216,7 @@ targets:
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/arena.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -7225,6 +7242,7 @@ targets:
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/arena.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
@ -7572,6 +7590,7 @@ targets:
  - src/core/lib/promise/race.h
  - src/core/lib/promise/seq.h
  - src/core/lib/resource_quota/memory_quota.h
  - src/core/lib/resource_quota/periodic_update.h
  - src/core/lib/resource_quota/resource_quota.h
  - src/core/lib/resource_quota/thread_quota.h
  - src/core/lib/resource_quota/trace.h
@ -7595,6 +7614,7 @@ targets:
  - src/core/lib/iomgr/iomgr_internal.cc
  - src/core/lib/promise/activity.cc
  - src/core/lib/resource_quota/memory_quota.cc
  - src/core/lib/resource_quota/periodic_update.cc
  - src/core/lib/resource_quota/resource_quota.cc
  - src/core/lib/resource_quota/thread_quota.cc
  - src/core/lib/resource_quota/trace.cc
--- a/config.m4
+++ b/config.m4
@ -618,6 +618,7 @@ if test "$PHP_GRPC" != "no"; then
    src/core/lib/resource_quota/api.cc \
    src/core/lib/resource_quota/arena.cc \
    src/core/lib/resource_quota/memory_quota.cc \
    src/core/lib/resource_quota/periodic_update.cc \
    src/core/lib/resource_quota/resource_quota.cc \
    src/core/lib/resource_quota/thread_quota.cc \
    src/core/lib/resource_quota/trace.cc \
--- a/config.w32
+++ b/config.w32
@ -584,6 +584,7 @@ if (PHP_GRPC != "no") {
    "src\\core\\lib\\resource_quota\\api.cc " +
    "src\\core\\lib\\resource_quota\\arena.cc " +
    "src\\core\\lib\\resource_quota\\memory_quota.cc " +
    "src\\core\\lib\\resource_quota\\periodic_update.cc " +
    "src\\core\\lib\\resource_quota\\resource_quota.cc " +
    "src\\core\\lib\\resource_quota\\thread_quota.cc " +
    "src\\core\\lib\\resource_quota\\trace.cc " +
--- a/gRPC-C++.podspec
+++ b/gRPC-C++.podspec
@ -833,6 +833,7 @@ Pod::Spec.new do |s|
                      'src/core/lib/resource_quota/api.h',
                      'src/core/lib/resource_quota/arena.h',
                      'src/core/lib/resource_quota/memory_quota.h',
                      'src/core/lib/resource_quota/periodic_update.h',
                      'src/core/lib/resource_quota/resource_quota.h',
                      'src/core/lib/resource_quota/thread_quota.h',
                      'src/core/lib/resource_quota/trace.h',
@ -1676,6 +1677,7 @@ Pod::Spec.new do |s|
                              'src/core/lib/resource_quota/api.h',
                              'src/core/lib/resource_quota/arena.h',
                              'src/core/lib/resource_quota/memory_quota.h',
                              'src/core/lib/resource_quota/periodic_update.h',
                              'src/core/lib/resource_quota/resource_quota.h',
                              'src/core/lib/resource_quota/thread_quota.h',
                              'src/core/lib/resource_quota/trace.h',
--- a/gRPC-Core.podspec
+++ b/gRPC-Core.podspec
@ -1349,6 +1349,8 @@ Pod::Spec.new do |s|
                      'src/core/lib/resource_quota/arena.h',
                      'src/core/lib/resource_quota/memory_quota.cc',
                      'src/core/lib/resource_quota/memory_quota.h',
                      'src/core/lib/resource_quota/periodic_update.cc',
                      'src/core/lib/resource_quota/periodic_update.h',
                      'src/core/lib/resource_quota/resource_quota.cc',
                      'src/core/lib/resource_quota/resource_quota.h',
                      'src/core/lib/resource_quota/thread_quota.cc',
@ -2291,6 +2293,7 @@ Pod::Spec.new do |s|
                              'src/core/lib/resource_quota/api.h',
                              'src/core/lib/resource_quota/arena.h',
                              'src/core/lib/resource_quota/memory_quota.h',
                              'src/core/lib/resource_quota/periodic_update.h',
                              'src/core/lib/resource_quota/resource_quota.h',
                              'src/core/lib/resource_quota/thread_quota.h',
                              'src/core/lib/resource_quota/trace.h',
--- a/grpc.gemspec
+++ b/grpc.gemspec
@ -1262,6 +1262,8 @@ Gem::Specification.new do |s|
  s.files += %w( src/core/lib/resource_quota/arena.h )
  s.files += %w( src/core/lib/resource_quota/memory_quota.cc )
  s.files += %w( src/core/lib/resource_quota/memory_quota.h )
  s.files += %w( src/core/lib/resource_quota/periodic_update.cc )
  s.files += %w( src/core/lib/resource_quota/periodic_update.h )
  s.files += %w( src/core/lib/resource_quota/resource_quota.cc )
  s.files += %w( src/core/lib/resource_quota/resource_quota.h )
  s.files += %w( src/core/lib/resource_quota/thread_quota.cc )
--- a/grpc.gyp
+++ b/grpc.gyp
@ -908,6 +908,7 @@
        'src/core/lib/resource_quota/api.cc',
        'src/core/lib/resource_quota/arena.cc',
        'src/core/lib/resource_quota/memory_quota.cc',
        'src/core/lib/resource_quota/periodic_update.cc',
        'src/core/lib/resource_quota/resource_quota.cc',
        'src/core/lib/resource_quota/thread_quota.cc',
        'src/core/lib/resource_quota/trace.cc',
@ -1366,6 +1367,7 @@
        'src/core/lib/resource_quota/api.cc',
        'src/core/lib/resource_quota/arena.cc',
        'src/core/lib/resource_quota/memory_quota.cc',
        'src/core/lib/resource_quota/periodic_update.cc',
        'src/core/lib/resource_quota/resource_quota.cc',
        'src/core/lib/resource_quota/thread_quota.cc',
        'src/core/lib/resource_quota/trace.cc',
--- a/package.xml
+++ b/package.xml
@ -1244,6 +1244,8 @@
    <file baseinstalldir="/" name="src/core/lib/resource_quota/arena.h" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/memory_quota.cc" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/memory_quota.h" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/periodic_update.cc" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/periodic_update.h" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/resource_quota.cc" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/resource_quota.h" role="src" />
    <file baseinstalldir="/" name="src/core/lib/resource_quota/thread_quota.cc" role="src" />
--- a/src/core/lib/resource_quota/memory_quota.cc
+++ b/src/core/lib/resource_quota/memory_quota.cc
@ -29,6 +29,7 @@
 #include "src/core/lib/debug/trace.h"
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/gprpp/global_config_env.h"
 #include "src/core/lib/gprpp/mpscq.h"
 #include "src/core/lib/promise/exec_ctx_wakeup_scheduler.h"
 #include "src/core/lib/promise/loop.h"
@ -37,6 +38,13 @@
 #include "src/core/lib/promise/seq.h"
 #include "src/core/lib/resource_quota/trace.h"
 GPR_GLOBAL_CONFIG_DEFINE_BOOL(
    grpc_experimental_enable_periodic_resource_quota_reclamation, false,
    "Enable experimental feature to reclaim resource quota periodically");
 GPR_GLOBAL_CONFIG_DEFINE_INT32(
    grpc_experimental_max_quota_buffer_size, 1024 * 1024,
    "Maximum size for one memory allocators buffer size against a quota");
 namespace grpc_core {
 // Maximum number of bytes an allocator will request from a quota in one step.
@ -249,11 +257,16 @@ absl::optional<size_t> GrpcMemoryAllocatorImpl::TryReserve(
 void GrpcMemoryAllocatorImpl::MaybeDonateBack() {
  size_t free = free_bytes_.load(std::memory_order_relaxed);
-  const size_t kReduceToSize = kMaxQuotaBufferSize / 2;
+  while (free > 0) {
-  while (true) {
+    size_t ret = 0;
-    if (free <= kReduceToSize) return;
+    if (max_quota_buffer_size() > 0 && free > max_quota_buffer_size() / 2) {
-    size_t ret = free - kReduceToSize;
+      ret = std::max(ret, free - max_quota_buffer_size() / 2);
-    if (free_bytes_.compare_exchange_weak(free, kReduceToSize,
+    }
    if (periodic_donate_back()) {
      ret = std::max(ret, free > 8192 ? free / 2 : free);
    }
    const size_t new_free = free - ret;
    if (free_bytes_.compare_exchange_weak(free, new_free,
                                          std::memory_order_acq_rel,
                                          std::memory_order_acquire)) {
      if (GRPC_TRACE_FLAG_ENABLED(grpc_resource_quota_trace)) {
--- a/src/core/lib/resource_quota/memory_quota.h
+++ b/src/core/lib/resource_quota/memory_quota.h
@ -34,11 +34,18 @@
 #include <grpc/event_engine/memory_request.h>
 #include <grpc/support/log.h>
 #include "src/core/lib/gprpp/global_config_generic.h"
 #include "src/core/lib/gprpp/orphanable.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 #include "src/core/lib/gprpp/sync.h"
 #include "src/core/lib/gprpp/time.h"
 #include "src/core/lib/promise/activity.h"
 #include "src/core/lib/promise/poll.h"
 #include "src/core/lib/resource_quota/periodic_update.h"
 GPR_GLOBAL_CONFIG_DECLARE_BOOL(
    grpc_experimental_enable_periodic_resource_quota_reclamation);
 GPR_GLOBAL_CONFIG_DECLARE_INT32(grpc_experimental_max_quota_buffer_size);
 namespace grpc_core {
@ -80,7 +87,6 @@ enum class ReclamationPass {
  kDestructive = 3,
 };
 static constexpr size_t kNumReclamationPasses = 4;
 static constexpr size_t kMaxQuotaBufferSize = 1024 * 1024;
 // For each reclamation function run we construct a ReclamationSweep.
 // When this object is finally destroyed (it may be moved several times first),
@ -299,7 +305,9 @@ class GrpcMemoryAllocatorImpl final : public EventEngineMemoryAllocatorImpl {
    // from  0 to non-zero, then we have more to do, otherwise, we're actually
    // done.
    size_t prev_free = free_bytes_.fetch_add(n, std::memory_order_release);
-    if (prev_free + n > kMaxQuotaBufferSize) {
+    if ((max_quota_buffer_size() > 0 &&
         prev_free + n > max_quota_buffer_size()) ||
        (periodic_donate_back() && donate_back_.Tick())) {
      // Try to immediately return some free'ed memory back to the total quota.
      MaybeDonateBack();
    }
@ -328,13 +336,20 @@ class GrpcMemoryAllocatorImpl final : public EventEngineMemoryAllocatorImpl {
  absl::string_view name() const { return name_; }
 private:
  static bool periodic_donate_back() {
    static const bool value = GPR_GLOBAL_CONFIG_GET(
        grpc_experimental_enable_periodic_resource_quota_reclamation);
    return value;
  }
  static size_t max_quota_buffer_size() {
    static const size_t value =
        GPR_GLOBAL_CONFIG_GET(grpc_experimental_max_quota_buffer_size);
    return value;
  }
  // Primitive reservation function.
  absl::optional<size_t> TryReserve(MemoryRequest request) GRPC_MUST_USE_RESULT;
-  // This function may be invoked during a memory release operation. If the
+  // This function may be invoked during a memory release operation.
-  // total free_bytes in this allocator/local cache exceeds
+  // It will try to return half of our free pool to the quota.
  // kMaxQuotaBufferSize / 2, donate the excess free_bytes in this cache back
  // to the total quota immediately. This helps prevent free bytes in any
  // particular allocator from growing too large.
  void MaybeDonateBack();
  // Replenish bytes from the quota, without blocking, possibly entering
  // overcommit.
@ -359,6 +374,8 @@ class GrpcMemoryAllocatorImpl final : public EventEngineMemoryAllocatorImpl {
  // Amount of memory taken from the quota by this allocator.
  std::atomic<size_t> taken_bytes_{sizeof(GrpcMemoryAllocatorImpl)};
  std::atomic<bool> registered_reclaimer_{false};
  // We try to donate back some memory periodically to the central quota.
  PeriodicUpdate donate_back_{Duration::Seconds(10)};
  Mutex reclaimer_mu_;
  bool shutdown_ ABSL_GUARDED_BY(reclaimer_mu_) = false;
  // Indices into the various reclaimer queues, used so that we can cancel
--- a/src/core/lib/resource_quota/periodic_update.cc
+++ b/src/core/lib/resource_quota/periodic_update.cc
@ -19,10 +19,16 @@
 #include <atomic>
 #include "src/core/lib/gpr/useful.h"
 #include "src/core/lib/iomgr/exec_ctx.h"
 namespace grpc_core {
 bool PeriodicUpdate::MaybeEndPeriod() {
  if (period_start_ == Timestamp::ProcessEpoch()) {
    period_start_ = ExecCtx::Get()->Now();
    updates_remaining_.store(1, std::memory_order_release);
    return false;
  }
  // updates_remaining_ just reached 0 and the thread calling this function was
  // the decrementer that got us there.
  // We can now safely mutate any non-atomic mutable variables (we've got a
--- a/src/core/lib/resource_quota/periodic_update.h
+++ b/src/core/lib/resource_quota/periodic_update.h
@ -22,7 +22,6 @@
 #include <atomic>
 #include "src/core/lib/gprpp/time.h"
 #include "src/core/lib/iomgr/exec_ctx.h"
 namespace grpc_core {
@ -60,7 +59,7 @@ class PeriodicUpdate {
  // this is fine because they'll observe an ignorable negative value.
  const Duration period_;
-  Timestamp period_start_ = ExecCtx::Get()->Now();
+  Timestamp period_start_ = Timestamp::ProcessEpoch();
  int64_t expected_updates_per_period_ = 1;
  std::atomic<int64_t> updates_remaining_{1};
 };
--- a/src/python/grpcio/grpc_core_dependencies.py
+++ b/src/python/grpcio/grpc_core_dependencies.py
@ -593,6 +593,7 @@ CORE_SOURCE_FILES = [
    'src/core/lib/resource_quota/api.cc',
    'src/core/lib/resource_quota/arena.cc',
    'src/core/lib/resource_quota/memory_quota.cc',
    'src/core/lib/resource_quota/periodic_update.cc',
    'src/core/lib/resource_quota/resource_quota.cc',
    'src/core/lib/resource_quota/thread_quota.cc',
    'src/core/lib/resource_quota/trace.cc',
--- a/tools/doxygen/Doxyfile.c++.internal
+++ b/tools/doxygen/Doxyfile.c++.internal
@ -2245,6 +2245,8 @@ src/core/lib/resource_quota/arena.cc \
 src/core/lib/resource_quota/arena.h \
 src/core/lib/resource_quota/memory_quota.cc \
 src/core/lib/resource_quota/memory_quota.h \
 src/core/lib/resource_quota/periodic_update.cc \
 src/core/lib/resource_quota/periodic_update.h \
 src/core/lib/resource_quota/resource_quota.cc \
 src/core/lib/resource_quota/resource_quota.h \
 src/core/lib/resource_quota/thread_quota.cc \
--- a/tools/doxygen/Doxyfile.core.internal
+++ b/tools/doxygen/Doxyfile.core.internal
@ -2039,6 +2039,8 @@ src/core/lib/resource_quota/arena.cc \
 src/core/lib/resource_quota/arena.h \
 src/core/lib/resource_quota/memory_quota.cc \
 src/core/lib/resource_quota/memory_quota.h \
 src/core/lib/resource_quota/periodic_update.cc \
 src/core/lib/resource_quota/periodic_update.h \
 src/core/lib/resource_quota/resource_quota.cc \
 src/core/lib/resource_quota/resource_quota.h \
 src/core/lib/resource_quota/thread_quota.cc \