From 2e601a2efc19d64ed0628a5973596e6331ddcc7c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20H=C3=B6gberg?= <john@erlang.org>
Date: Mon, 8 Jan 2018 11:45:33 +0100
Subject: Remove sender punishment

The reduction cost of sending messages is now constant and will no
longer scale according to the length of the receiving process'
message queue.
---
 erts/emulator/beam/bif.c      | 29 ++++++-----------------------
 erts/emulator/beam/erl_init.c |  7 -------
 erts/emulator/beam/global.h   |  1 -
 3 files changed, 6 insertions(+), 31 deletions(-)

diff --git a/erts/emulator/beam/bif.c b/erts/emulator/beam/bif.c
index 0e5f7bb22b..f086c434ea 100644
--- a/erts/emulator/beam/bif.c
+++ b/erts/emulator/beam/bif.c
@@ -2244,20 +2244,15 @@ do_send(Process *p, Eterm to, Eterm msg, Eterm *refp, ErtsSendContext *ctx)
     
  send_message: {
 	ErtsProcLocks rp_locks = 0;
-	Sint res;
 	if (p == rp)
 	    rp_locks |= ERTS_PROC_LOCK_MAIN;
 	/* send to local process */
-	res = erts_send_message(p, rp, &rp_locks, msg, 0);
-	if (erts_use_sender_punish)
-	    res *= 4;
-	else
-	    res = 0;
+	erts_send_message(p, rp, &rp_locks, msg, 0);
 	erts_proc_unlock(rp,
 			     p == rp
 			     ? (rp_locks & ~ERTS_PROC_LOCK_MAIN)
 			     : rp_locks);
-	return res;
+	return 0;
     }
 }
 
@@ -2312,8 +2307,8 @@ BIF_RETTYPE send_3(BIF_ALIST_3)
     result = do_send(p, to, msg, &ref, ctx);
     ERTS_MSACC_POP_STATE_M_X();
 
-    if (result > 0) {
-	ERTS_VBUMP_REDS(p, result);
+    if (result >= 0) {
+	ERTS_VBUMP_REDS(p, 4);
 	if (ERTS_IS_PROC_OUT_OF_REDS(p))
 	    goto yield_return;
 	ERTS_BIF_PREP_RET(retval, am_ok);
@@ -2321,12 +2316,6 @@ BIF_RETTYPE send_3(BIF_ALIST_3)
     }
 
     switch (result) {
-    case 0:
-	/* May need to yield even though we do not bump reds here... */
-	if (ERTS_IS_PROC_OUT_OF_REDS(p))
-	    goto yield_return;
-	ERTS_BIF_PREP_RET(retval, am_ok);
-	break;
     case SEND_NOCONNECT:
 	if (ctx->connect) {
 	    ERTS_BIF_PREP_RET(retval, am_ok);
@@ -2443,8 +2432,8 @@ Eterm erl_send(Process *p, Eterm to, Eterm msg)
 
     ERTS_MSACC_POP_STATE_M_X();
 
-    if (result > 0) {
-	ERTS_VBUMP_REDS(p, result);
+    if (result >= 0) {
+	ERTS_VBUMP_REDS(p, 4);
 	if (ERTS_IS_PROC_OUT_OF_REDS(p))
 	    goto yield_return;
 	ERTS_BIF_PREP_RET(retval, msg);
@@ -2452,12 +2441,6 @@ Eterm erl_send(Process *p, Eterm to, Eterm msg)
     }
 
     switch (result) {
-    case 0:
-	/* May need to yield even though we do not bump reds here... */
-	if (ERTS_IS_PROC_OUT_OF_REDS(p))
-	    goto yield_return;
-	ERTS_BIF_PREP_RET(retval, msg);
-	break;
     case SEND_NOCONNECT:
 	ERTS_BIF_PREP_RET(retval, msg);
 	break;
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index f52eed41d5..4846ccd2d3 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -155,9 +155,6 @@ erts_atomic32_t erts_writing_erl_crash_dump;
 erts_tsd_key_t erts_is_crash_dumping_key;
 int erts_initialized = 0;
 
-
-int erts_use_sender_punish;
-
 /*
  * Configurable parameters.
  */
@@ -758,8 +755,6 @@ early_init(int *argc, char **argv) /*
 
     erts_initialized = 0;
 
-    erts_use_sender_punish = 1;
-
     erts_pre_early_init_cpu_topology(&max_reader_groups,
 				     &ncpu,
 				     &ncpuonln,
@@ -1765,8 +1760,6 @@ erl_start(int argc, char **argv)
 		    erts_usage();
 		}
 	    }
-	    else if (sys_strcmp("nsp", sub_param) == 0)
-		erts_use_sender_punish = 0;
 	    else if (has_prefix("tbt", sub_param)) {
 		arg = get_arg(sub_param+3, argv[i+1], &i);
 		res = erts_init_scheduler_bind_type_string(arg);
diff --git a/erts/emulator/beam/global.h b/erts/emulator/beam/global.h
index 09500c5bc0..d16ab75178 100644
--- a/erts/emulator/beam/global.h
+++ b/erts/emulator/beam/global.h
@@ -1122,7 +1122,6 @@ extern int erts_no_line_info;
 extern Eterm erts_error_logger_warnings;
 extern int erts_initialized;
 extern int erts_compat_rel;
-extern int erts_use_sender_punish;
 void erl_start(int, char**);
 void erts_usage(void);
 Eterm erts_preloaded(Process* p);
-- 
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