[memory] Re-align caches for transport, stream, and tcp (#34397)

Cache realignment saves 64 bytes per transport, 40 bytes per stream, 8
bytes per tcp endpoint, and 24 bytes per transport op.

src/core/ext/transport/chttp2/transport/chttp2_transport.cc

@@ -575,7 +575,6 @@ grpc_chttp2_transport::grpc_chttp2_transport(
       combiner(grpc_combiner_create(event_engine)),
       state_tracker(is_client ? "client_transport" : "server_transport",
                     GRPC_CHANNEL_READY),
-      is_client(is_client),
       next_stream_id(is_client ? 1 : 2),
       ping_abuse_policy(channel_args),
       ping_rate_policy(channel_args, is_client),
@@ -583,7 +582,8 @@ grpc_chttp2_transport::grpc_chttp2_transport(
           peer_string.as_string_view(),
           channel_args.GetBool(GRPC_ARG_HTTP2_BDP_PROBE).value_or(true),
           &memory_owner),
-      deframe_state(is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0) {
+      deframe_state(is_client ? GRPC_DTS_FH_0 : GRPC_DTS_CLIENT_PREFIX_0),
+      is_client(is_client) {
   cl = new grpc_core::ContextList();
   GPR_ASSERT(strlen(GRPC_CHTTP2_CLIENT_CONNECT_STRING) ==
              GRPC_CHTTP2_CLIENT_CONNECT_STRLEN);

src/core/ext/transport/chttp2/transport/internal.h

@@ -275,17 +275,9 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   grpc_closure* notify_on_receive_settings = nullptr;
   grpc_closure* notify_on_close = nullptr;
 
-  /// write execution state of the transport
-  grpc_chttp2_write_state write_state = GRPC_CHTTP2_WRITE_STATE_IDLE;
-
-  /// is the transport destroying itself?
-  uint8_t destroying = false;
   /// has the upper layer closed the transport?
   grpc_error_handle closed_with_error;
 
-  /// is there a read request to the endpoint outstanding?
-  uint8_t endpoint_reading = 1;
-
   /// various lists of streams
   grpc_chttp2_stream_list lists[STREAM_LIST_COUNT] = {};
 
@@ -322,26 +314,16 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   grpc_slice_buffer outbuf;
   /// hpack encoding
   grpc_core::HPackCompressor hpack_compressor;
-  /// is this a client?
-  bool is_client;
 
   /// data to write next write
   grpc_slice_buffer qbuf;
 
-  /// how much data are we willing to buffer when the WRITE_BUFFER_HINT is set?
-  ///
-  uint32_t write_buffer_size = grpc_core::chttp2::kDefaultWindow;
-
   /// Set to a grpc_error object if a goaway frame is received. By default, set
   /// to absl::OkStatus()
   grpc_error_handle goaway_error;
 
   grpc_chttp2_sent_goaway_state sent_goaway_state = GRPC_CHTTP2_NO_GOAWAY_SEND;
 
-  /// are the local settings dirty and need to be sent?
-  bool dirtied_local_settings = true;
-  /// have local settings been sent?
-  bool sent_local_settings = false;
   /// bitmask of setting indexes to send out
   /// Hack: it's common for implementations to assume 65536 bytes initial send
   /// window -- this should by rights be 0
@@ -396,7 +378,6 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   bool is_first_frame = true;
   uint32_t expect_continuation_stream_id = 0;
   uint32_t incoming_frame_size = 0;
-  uint32_t incoming_stream_id = 0;
 
   grpc_chttp2_stream* incoming_stream = nullptr;
   // active parser
@@ -412,8 +393,6 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   grpc_chttp2_write_cb* write_cb_pool = nullptr;
 
   // bdp estimator
-  bool bdp_ping_blocked =
-      false;  // Is the BDP blocked due to not receiving any data?
   grpc_closure next_bdp_ping_timer_expired_locked;
   grpc_closure start_bdp_ping_locked;
   grpc_closure finish_bdp_ping_locked;
@@ -425,19 +404,11 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   grpc_closure_list run_after_write = GRPC_CLOSURE_LIST_INIT;
 
   // buffer pool state
-  /// have we scheduled a benign cleanup?
-  bool benign_reclaimer_registered = false;
-  /// have we scheduled a destructive cleanup?
-  bool destructive_reclaimer_registered = false;
   /// benign cleanup closure
   grpc_closure benign_reclaimer_locked;
   /// destructive cleanup closure
   grpc_closure destructive_reclaimer_locked;
 
-  /// If start_bdp_ping_locked has been called
-  bool bdp_ping_started = false;
-  // True if pings should be acked
-  bool ack_pings = true;
   // next bdp ping timer handle
   absl::optional<grpc_event_engine::experimental::EventEngine::TaskHandle>
       next_bdp_ping_timer_handle;
@@ -461,10 +432,6 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   grpc_core::Duration keepalive_time;
   /// grace period for a ping to complete before watchdog kicks in
   grpc_core::Duration keepalive_timeout;
-  /// if keepalive pings are allowed when there's no outstanding streams
-  bool keepalive_permit_without_calls = false;
-  /// If start_keepalive_ping_locked has been called
-  bool keepalive_ping_started = false;
   /// keep-alive state machine state
   grpc_chttp2_keepalive_state keepalive_state;
   // Soft limit on max header size.
@@ -478,6 +445,12 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   /// only continue reading when we are able to write to the socket again,
   /// thereby reducing the number of induced frames.
   uint32_t num_pending_induced_frames = 0;
+  uint32_t incoming_stream_id = 0;
+
+  /// how much data are we willing to buffer when the WRITE_BUFFER_HINT is set?
+  ///
+  uint32_t write_buffer_size = grpc_core::chttp2::kDefaultWindow;
+
   bool reading_paused_on_pending_induced_frames = false;
   /// Based on channel args, preferred_rx_crypto_frame_sizes are advertised to
   /// the peer
@@ -486,6 +459,42 @@ struct grpc_chttp2_transport : public grpc_core::KeepsGrpcInitialized {
   /// covering a write in a pollset. Such closures cannot be scheduled until
   /// we can prove that the write got scheduled.
   uint8_t closure_barrier_may_cover_write = CLOSURE_BARRIER_MAY_COVER_WRITE;
+
+  /// have we scheduled a benign cleanup?
+  bool benign_reclaimer_registered = false;
+  /// have we scheduled a destructive cleanup?
+  bool destructive_reclaimer_registered = false;
+
+  /// if keepalive pings are allowed when there's no outstanding streams
+  bool keepalive_permit_without_calls = false;
+  /// If start_keepalive_ping_locked has been called
+  bool keepalive_ping_started = false;
+
+  // bdp estimator
+  bool bdp_ping_blocked =
+      false;  // Is the BDP blocked due to not receiving any data?
+
+  /// is the transport destroying itself?
+  uint8_t destroying = false;
+
+  /// is there a read request to the endpoint outstanding?
+  uint8_t endpoint_reading = 1;
+
+  /// is this a client?
+  bool is_client;
+
+  /// are the local settings dirty and need to be sent?
+  bool dirtied_local_settings = true;
+  /// have local settings been sent?
+  bool sent_local_settings = false;
+
+  /// If start_bdp_ping_locked has been called
+  bool bdp_ping_started = false;
+  // True if pings should be acked
+  bool ack_pings = true;
+
+  /// write execution state of the transport
+  grpc_chttp2_write_state write_state = GRPC_CHTTP2_WRITE_STATE_IDLE;
 };
 
 typedef enum {
@@ -508,7 +517,6 @@ struct grpc_chttp2_stream {
   grpc_closure* destroy_stream_arg;
 
   grpc_chttp2_stream_link links[STREAM_LIST_COUNT];
-  grpc_core::BitSet<STREAM_LIST_COUNT> included;
 
   /// HTTP2 stream id for this stream, or zero if one has not been assigned
   uint32_t id = 0;
@@ -534,7 +542,6 @@ struct grpc_chttp2_stream {
   grpc_metadata_batch* recv_initial_metadata;
   grpc_closure* recv_initial_metadata_ready = nullptr;
   bool* trailing_metadata_available = nullptr;
-  bool parsed_trailers_only = false;
   absl::optional<grpc_core::SliceBuffer>* recv_message = nullptr;
   uint32_t* recv_message_flags = nullptr;
   bool* call_failed_before_recv_message = nullptr;
@@ -562,30 +569,25 @@ struct grpc_chttp2_stream {
   bool eos_received = false;
   bool eos_sent = false;
 
+  grpc_core::BitSet<STREAM_LIST_COUNT> included;
+
   /// the error that resulted in this stream being read-closed
   grpc_error_handle read_closed_error;
   /// the error that resulted in this stream being write-closed
   grpc_error_handle write_closed_error;
 
   grpc_published_metadata_method published_metadata[2] = {};
-  bool final_metadata_requested = false;
 
   grpc_metadata_batch initial_metadata_buffer;
   grpc_metadata_batch trailing_metadata_buffer;
 
-  grpc_slice_buffer frame_storage;   // protected by t combiner
-  bool received_last_frame = false;  // protected by t combiner
+  grpc_slice_buffer frame_storage;  // protected by t combiner
 
   grpc_core::Timestamp deadline = grpc_core::Timestamp::InfFuture();
 
-  /// how many header frames have we received?
-  uint8_t header_frames_received = 0;
   /// number of bytes received - reset at end of parse thread execution
   int64_t received_bytes = 0;
 
-  bool sent_initial_metadata = false;
-  bool sent_trailing_metadata = false;
-
   grpc_core::chttp2::StreamFlowControl flow_control;
 
   grpc_slice_buffer flow_controlled_buffer;
@@ -595,13 +597,25 @@ struct grpc_chttp2_stream {
   grpc_chttp2_write_cb* finish_after_write = nullptr;
   size_t sending_bytes = 0;
 
-  /// Whether the bytes needs to be traced using Fathom
-  bool traced = false;
   /// Byte counter for number of bytes written
   size_t byte_counter = 0;
 
   // time this stream was created
   gpr_timespec creation_time = gpr_now(GPR_CLOCK_MONOTONIC);
+
+  bool parsed_trailers_only = false;
+
+  bool final_metadata_requested = false;
+  bool received_last_frame = false;  // protected by t combiner
+
+  /// how many header frames have we received?
+  uint8_t header_frames_received = 0;
+
+  bool sent_initial_metadata = false;
+  bool sent_trailing_metadata = false;
+
+  /// Whether the bytes needs to be traced using Fathom
+  bool traced = false;
 };
 
 /// Transport writing call flow:

src/core/lib/iomgr/tcp_posix.cc

@@ -479,10 +479,7 @@ struct grpc_tcp {
   grpc_endpoint base;
   grpc_fd* em_fd;
   int fd;
-  // Used by the endpoint read function to distinguish the very first read call
-  // from the rest
-  bool is_first_read;
-  bool has_posted_reclaimer ABSL_GUARDED_BY(read_mu) = false;
+  int inq;  // bytes pending on the socket from the last read.
   double target_length;
   double bytes_read_this_round;
   grpc_core::RefCount refcount;
@@ -490,15 +487,12 @@ struct grpc_tcp {
 
   int min_read_chunk_size;
   int max_read_chunk_size;
-  int set_rcvlowat = 0;
 
   // garbage after the last read
   grpc_slice_buffer last_read_buffer;
 
   grpc_core::Mutex read_mu;
   grpc_slice_buffer* incoming_buffer ABSL_GUARDED_BY(read_mu) = nullptr;
-  int inq;           // bytes pending on the socket from the last read.
-  bool inq_capable;  // cache whether kernel supports inq
 
   grpc_slice_buffer* outgoing_buffer;
   // byte within outgoing_buffer->slices[0] to write next
@@ -535,17 +529,26 @@ struct grpc_tcp {
   // options for collecting timestamps are set, and is incremented with each
   // byte sent.
   int bytes_counter;
-  bool socket_ts_enabled;  // True if timestamping options are set on the socket
-                           //
-  bool ts_capable;         // Cache whether we can set timestamping options
+
+  int min_progress_size;  // A hint from upper layers specifying the minimum
+                          // number of bytes that need to be read to make
+                          // meaningful progress
+
   gpr_atm stop_error_notification;  // Set to 1 if we do not want to be notified
                                     // on errors anymore
   TcpZerocopySendCtx tcp_zerocopy_send_ctx;
   TcpZerocopySendRecord* current_zerocopy_send = nullptr;
 
-  int min_progress_size;  // A hint from upper layers specifying the minimum
-                          // number of bytes that need to be read to make
-                          // meaningful progress
+  int set_rcvlowat = 0;
+
+  // Used by the endpoint read function to distinguish the very first read call
+  // from the rest
+  bool is_first_read;
+  bool has_posted_reclaimer ABSL_GUARDED_BY(read_mu) = false;
+  bool inq_capable;        // cache whether kernel supports inq
+  bool socket_ts_enabled;  // True if timestamping options are set on the socket
+                           //
+  bool ts_capable;         // Cache whether we can set timestamping options
 };
 
 struct backup_poller {

src/core/lib/transport/transport.h

@@ -508,7 +508,6 @@ typedef struct grpc_transport_op {
   /// connectivity monitoring - set connectivity_state to NULL to unsubscribe
   grpc_core::OrphanablePtr<grpc_core::ConnectivityStateWatcherInterface>
       start_connectivity_watch;
-  grpc_connectivity_state start_connectivity_watch_state = GRPC_CHANNEL_IDLE;
   grpc_core::ConnectivityStateWatcherInterface* stop_connectivity_watch =
       nullptr;
   /// should the transport be disconnected
@@ -519,27 +518,11 @@ typedef struct grpc_transport_op {
   /// Error contract: the transport that gets this op must cause
   ///                goaway_error to be unref'ed after processing it
   grpc_error_handle goaway_error;
-  /// set the callback for accepting new streams;
-  /// this is a permanent callback, unlike the other one-shot closures.
-  /// If true, the callback is set to set_accept_stream_fn, with its
-  /// user_data argument set to set_accept_stream_user_data.
-  /// `set_registered_method_matcher_fn` is also set with its user_data argument
-  /// set to set_accept_stream_user_data. The transport should invoke
-  /// `set_registered_method_matcher_fn` after initial metadata is received but
-  /// before recv_initial_metadata_ready callback is invoked. If the transport
-  /// detects an error in the stream, invoking
-  /// `set_registered_method_matcher_fn` can be skipped.
-  bool set_accept_stream = false;
   void (*set_accept_stream_fn)(void* user_data, grpc_transport* transport,
                                const void* server_data) = nullptr;
   void (*set_registered_method_matcher_fn)(
       void* user_data, grpc_core::ServerMetadata* metadata) = nullptr;
   void* set_accept_stream_user_data = nullptr;
-  /// set the callback for accepting new streams based upon promises;
-  /// this is a permanent callback, unlike the other one-shot closures.
-  /// If true, the callback is set to set_make_promise_fn, with its
-  /// user_data argument set to set_make_promise_data
-  bool set_make_promise = false;
   void (*set_make_promise_fn)(void* user_data, grpc_transport* transport,
                               const void* server_data) = nullptr;
   void* set_make_promise_user_data = nullptr;
@@ -555,9 +538,28 @@ typedef struct grpc_transport_op {
     /// Called when the ping ack is received
     grpc_closure* on_ack = nullptr;
   } send_ping;
+  grpc_connectivity_state start_connectivity_watch_state = GRPC_CHANNEL_IDLE;
   // If true, will reset the channel's connection backoff.
   bool reset_connect_backoff = false;
 
+  /// set the callback for accepting new streams;
+  /// this is a permanent callback, unlike the other one-shot closures.
+  /// If true, the callback is set to set_accept_stream_fn, with its
+  /// user_data argument set to set_accept_stream_user_data.
+  /// `set_registered_method_matcher_fn` is also set with its user_data argument
+  /// set to set_accept_stream_user_data. The transport should invoke
+  /// `set_registered_method_matcher_fn` after initial metadata is received but
+  /// before recv_initial_metadata_ready callback is invoked. If the transport
+  /// detects an error in the stream, invoking
+  /// `set_registered_method_matcher_fn` can be skipped.
+  bool set_accept_stream = false;
+
+  /// set the callback for accepting new streams based upon promises;
+  /// this is a permanent callback, unlike the other one-shot closures.
+  /// If true, the callback is set to set_make_promise_fn, with its
+  /// user_data argument set to set_make_promise_data
+  bool set_make_promise = false;
+
   //**************************************************************************
   // remaining fields are initialized and used at the discretion of the
   // transport implementation