File 1911-Enable-possibility-to-skip-reading-CPU-top... of Package erlang

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File 1911-Enable-possibility-to-skip-reading-CPU-topology-at-s.patch of Package erlang (Revision 1c6d27e874ff4bb28c5c2e74b90a1fc8)

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From d5688f9a89baf1653a0b0e07115f601bc97c2b12 Mon Sep 17 00:00:00 2001
From: Hakan Nilsson <hanilsso@cisco.com>
Date: Mon, 13 Sep 2021 09:34:54 +0200
Subject: [PATCH] Enable possibility to skip reading CPU topology at startup

Reading CPU topology slows down startup when starting many
parallel instances of ERTS on systems with large amount of cores,
this commit adds the possibility to skip it.

Use new emulator flag +ssrct to skip reading CPU topology.
Reading CPU topology will also be skipped if a user defined topology
is set using the +sct flag.
---
 erts/doc/src/erl_cmd.xml               | 10 ++++++++++
 erts/emulator/beam/erl_cpu_topology.c  |  6 ++++--
 erts/emulator/beam/erl_cpu_topology.h  |  3 ++-
 erts/emulator/beam/erl_init.c          | 21 ++++++++++++++++++--
 erts/emulator/test/scheduler_SUITE.erl | 27 ++++++++++++++++++++++++++
 erts/include/internal/erl_misc_utils.h |  2 +-
 erts/lib_src/common/erl_misc_utils.c   |  9 ++++++---
 7 files changed, 69 insertions(+), 9 deletions(-)

diff --git a/erts/doc/src/erl_cmd.xml b/erts/doc/src/erl_cmd.xml
index 7ef3ca88f9..7365f917cd 100644
--- a/erts/doc/src/erl_cmd.xml
+++ b/erts/doc/src/erl_cmd.xml
@@ -1511,6 +1511,16 @@ $ <input>erl \
 <seeerl marker="erlang#system_info_cpu_topology">
 <c>erlang:system_info(cpu_topology)</c></seeerl>.
 </item>
+ <tag><marker id="+ssrct"/><c>+ssrct</c></tag>
+ <item>
+ Skips reading CPU topology.
+ <note>
+ Reading CPU topology slows down startup when starting many
+ parallel instances of ERTS on systems with large amount of
+ cores, using this flag might speed up execution in such
+ scenarios.
+ </note>
+ </item>
 <tag><marker id="+sfwi"/><c>+sfwi Interval</c></tag>
 <item>
 Sets scheduler-forced wakeup interval. All run queues are
diff --git a/erts/emulator/beam/erl_cpu_topology.c b/erts/emulator/beam/erl_cpu_topology.c
index 91a99077f8..0c4bc433df 100644
--- a/erts/emulator/beam/erl_cpu_topology.c
+++ b/erts/emulator/beam/erl_cpu_topology.c
@@ -1674,8 +1674,10 @@ erts_early_init_cpu_topology(int no_schedulers,
 			 int max_reader_groups,
 			 int *reader_groups_p,
 int max_decentralized_counter_groups,
- int *decentralized_counter_groups_p)
+ int *decentralized_counter_groups_p,
+ int skip_read_topology)
 {
+ erts_cpu_info_update(cpuinfo, skip_read_topology);
 user_cpudata = NULL;
 user_cpudata_size = 0;
 
@@ -1758,7 +1760,7 @@ erts_update_cpu_info(void)
 {
 int changed;
 erts_rwmtx_rwlock(&cpuinfo_rwmtx);
- changed = erts_cpu_info_update(cpuinfo);
+ changed = erts_cpu_info_update(cpuinfo, 0);
 if (changed) {
 	erts_cpu_topology_t *cpudata;
 	int cpudata_size;
diff --git a/erts/emulator/beam/erl_cpu_topology.h b/erts/emulator/beam/erl_cpu_topology.h
index 62bd0e73b6..6b4a73a1a0 100644
--- a/erts/emulator/beam/erl_cpu_topology.h
+++ b/erts/emulator/beam/erl_cpu_topology.h
@@ -40,7 +40,8 @@ erts_early_init_cpu_topology(int no_schedulers,
 			 int max_reader_groups,
 			 int *reader_groups_p,
 int max_decentralized_counter_groups,
- int *decentralized_counter_groups_p);
+ int *decentralized_counter_groups_p,
+ int skip_read_topology);
 void erts_init_cpu_topology(void);
 
 
diff --git a/erts/emulator/beam/erl_init.c b/erts/emulator/beam/erl_init.c
index cc2a168813..8d00015399 100644
--- a/erts/emulator/beam/erl_init.c
+++ b/erts/emulator/beam/erl_init.c
@@ -682,6 +682,7 @@ void erts_usage(void)
 erts_fprintf(stderr, " none | very_short | short | medium | long | very_long\n");
 erts_fprintf(stderr, "-scl bool enable/disable compaction of scheduler load\n");
 erts_fprintf(stderr, "-sct cput set cpu topology\n");
+ erts_fprintf(stderr, "-ssrct skip reading cpu topology\n");
 erts_fprintf(stderr, "-secio bool enable or disable eager check I/O scheduling\n");
 #if ERTS_HAVE_SCHED_UTIL_BALANCING_SUPPORT_OPT
 erts_fprintf(stderr, "-sub bool enable or disable scheduler utilization balancing\n");
@@ -829,6 +830,7 @@ early_init(int *argc, char **argv) /*
 int decentralized_counter_groups;
 char envbuf[21]; /* enough for any 64-bit integer */
 size_t envbufsz;
+ int skip_read_topology = 0;
 
 erts_save_emu_args(*argc, argv);
 
@@ -968,7 +970,18 @@ early_init(int *argc, char **argv) /*
 		 }
 		 break;
 		}
-
+		case 's' : {
+		 char *sub_param = argv[i]+2;
+		 if (has_prefix("srct", sub_param)) {
+			/* skip reading cpu topology */
+			skip_read_topology = 1;
+		 }
+		 else if (has_prefix("ct", sub_param)) {
+			/* cpu topology */
+			skip_read_topology = 1;
+		 }
+		 break;
+		}
 		case 'S' :
 		 if (argv[i][2] == 'P') {
 			int ptot, ponln;
@@ -1262,7 +1275,8 @@ early_init(int *argc, char **argv) /*
 				 max_reader_groups,
 				 &reader_groups,
 max_decentralized_counter_groups,
- &decentralized_counter_groups);
+ &decentralized_counter_groups,
+ skip_read_topology);
 erts_flxctr_setup(decentralized_counter_groups);
 {
 	erts_thr_late_init_data_t elid = ERTS_THR_LATE_INIT_DATA_DEF_INITER;
@@ -2088,6 +2102,9 @@ erl_start(int argc, char **argv)
 		}
 		erts_runq_supervision_interval = val;
 	 }
+	 else if (has_prefix("srct", sub_param)) {
+		/* skip reading cpu topology, already handled */
+	 }
 	 else {
 		erts_fprintf(stderr, "bad scheduling option %s\n", argv[i]);
 		erts_usage();
diff --git a/erts/emulator/test/scheduler_SUITE.erl b/erts/emulator/test/scheduler_SUITE.erl
index faf16a96ef..041df6f2f0 100644
--- a/erts/emulator/test/scheduler_SUITE.erl
+++ b/erts/emulator/test/scheduler_SUITE.erl
@@ -52,6 +52,7 @@
 	 cpu_topology/1,
 	 update_cpu_info/1,
 	 sct_cmd/1,
+	 ssrct_cmd/1,
 	 sbt_cmd/1,
 	 scheduler_threads/1,
 	 scheduler_suspend_basic/1,
@@ -786,6 +787,8 @@ cpu_topology_bif_test(Config, Topology) ->
 {ok, Peer, Node} = ?CT_PEER(),
 _ = rpc:call(Node, erlang, system_flag, [cpu_topology, Topology]),
 cmp(Topology, rpc:call(Node, erlang, system_info, [cpu_topology])),
+ cmp(Topology,
+ rpc:call(Node, erlang, system_info, [{cpu_topology, defined}])),
 peer:stop(Peer),
 ok.
 
@@ -794,6 +797,10 @@ cpu_topology_cmdline_test(_Config, _Topology, false) ->
 cpu_topology_cmdline_test(Topology, Cmd) ->
 {ok, Peer, Node} = ?CT_PEER(Cmd),
 cmp(Topology, rpc:call(Node, erlang, system_info, [cpu_topology])),
+ cmp(undefined,
+ rpc:call(Node, erlang, system_info, [{cpu_topology, detected}])),
+ cmp(Topology,
+ rpc:call(Node, erlang, system_info, [{cpu_topology, defined}])),
 peer:stop(Peer),
 ok.
 
@@ -979,6 +986,10 @@ sct_cmd(Config) when is_list(Config) ->
 	{ok, Peer, Node} = ?CT_PEER(?TOPOLOGY_A_CMD),
 	cmp(Topology,
 		 rpc:call(Node, erlang, system_info, [cpu_topology])),
+	cmp(undefined,
+		 rpc:call(Node, erlang, system_info, [{cpu_topology, detected}])),
+	cmp(Topology,
+		 rpc:call(Node, erlang, system_info, [{cpu_topology, defined}])),
 	cmp(Topology,
 		 rpc:call(Node, erlang, system_flag, [cpu_topology, Topology])),
 	cmp(Topology,
@@ -989,6 +1000,22 @@ sct_cmd(Config) when is_list(Config) ->
 end,
 ok.
 
+ssrct_cmd(Config) when is_list(Config) ->
+ OldRelFlags = clear_erl_rel_flags(),
+ try
+ {ok, Node} = start_node(Config, "+ssrct"),
+ cmp(undefined,
+ rpc:call(Node, erlang, system_info, [cpu_topology])),
+ cmp(undefined,
+ rpc:call(Node, erlang, system_info, [{cpu_topology, detected}])),
+ cmp(undefined,
+ rpc:call(Node, erlang, system_info, [{cpu_topology, defined}])),
+ stop_node(Node)
+ after
+ restore_erl_rel_flags(OldRelFlags)
+ end,
+ ok.
+
 -define(BIND_TYPES,
 	[{"u", unbound},
 	 {"ns", no_spread},
diff --git a/erts/include/internal/erl_misc_utils.h b/erts/include/internal/erl_misc_utils.h
index 59933ade4b..b3de4d0360 100644
--- a/erts/include/internal/erl_misc_utils.h
+++ b/erts/include/internal/erl_misc_utils.h
@@ -35,7 +35,7 @@ typedef struct {
 
 erts_cpu_info_t *erts_cpu_info_create(void);
 void erts_cpu_info_destroy(erts_cpu_info_t *cpuinfo);
-int erts_cpu_info_update(erts_cpu_info_t *cpuinfo);
+int erts_cpu_info_update(erts_cpu_info_t *cpuinfo, int skip_read_topology);
 int erts_get_cpu_configured(erts_cpu_info_t *cpuinfo);
 int erts_get_cpu_online(erts_cpu_info_t *cpuinfo);
 int erts_get_cpu_available(erts_cpu_info_t *cpuinfo);
diff --git a/erts/lib_src/common/erl_misc_utils.c b/erts/lib_src/common/erl_misc_utils.c
index 9b6c8341dc..ba49b76709 100644
--- a/erts/lib_src/common/erl_misc_utils.c
+++ b/erts/lib_src/common/erl_misc_utils.c
@@ -234,7 +234,7 @@ erts_cpu_info_create(void)
 cpuinfo->online = -1;
 cpuinfo->available = -1;
 cpuinfo->quota = -1;
- erts_cpu_info_update(cpuinfo);
+ erts_cpu_info_update(cpuinfo, 1);
 return cpuinfo;
 }
 
@@ -259,7 +259,8 @@ erts_cpu_info_destroy(erts_cpu_info_t *cpuinfo)
 }
 
 int
-erts_cpu_info_update(erts_cpu_info_t *cpuinfo)
+erts_cpu_info_update(erts_cpu_info_t *cpuinfo,
+ int skip_read_topology)
 {
 int changed = 0;
 int configured = 0;
@@ -424,7 +425,9 @@ erts_cpu_info_update(erts_cpu_info_t *cpuinfo)
 old_topology_size = cpuinfo->topology_size;
 cpuinfo->topology = NULL;
 
- read_topology(cpuinfo);
+ if (!skip_read_topology) {
+ read_topology(cpuinfo);
+ }
 
 if (cpuinfo->topology_size != old_topology_size
 	|| (old_topology_size != 0
-- 
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File 1911-Enable-possibility-to-skip-reading-CPU-topology-at-s.patch of Package erlang (Revision 1c6d27e874ff4bb28c5c2e74b90a1fc8)

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