Make it possible to reread and update detected CPU information

Calling erlang:system_info/1 with the new argument 'update_cpu_info'
will make the runtime system reread and update the internally stored
CPU information. For more information see the documentation of
erlang:system_info(update_cpu_info).

6 files changed, 258 insertions, 73 deletions

diff --git a/erts/doc/src/erlang.xml b/erts/doc/src/erlang.xml
index 54a0a80536..cb3112acfe 100644
--- a/erts/doc/src/erlang.xml
+++ b/erts/doc/src/erlang.xml
@@ -5533,7 +5533,7 @@ true</pre>
 	       <c>CpuTopology</c> type to change.
 	    </p>
           </item>
-          <tag><c>{cpu_topology, defined}</c></tag>
+          <tag><marker id="system_info_cpu_topology_defined"><c>{cpu_topology, defined}</c></marker></tag>
           <item>
             <p>Returns the user defined <c>CpuTopology</c>. For more
 	       information see the documentation of
@@ -5543,7 +5543,7 @@ true</pre>
 	       argument.
 	    </p>
           </item>
-          <tag><c>{cpu_topology, detected}</c></tag>
+          <tag><marker id="system_info_cpu_topology_detected"><c>{cpu_topology, detected}</c></marker></tag>
           <item>
             <p>Returns the automatically detected <c>CpuTopology</c>. The
 	       emulator currently only detects the CPU topology on some newer
@@ -5727,11 +5727,34 @@ true</pre>
               information see the <seealso marker="erts:crash_dump">"How to interpret the Erlang crash dumps"</seealso> chapter
               in the ERTS User's Guide.</p>
           </item>
-	  <tag><c>logical_processors</c></tag>
+	  <tag><marker id="logical_processors"><c>logical_processors</c></marker></tag>
           <item>
-            <p>Returns the number of logical processors detected on the
-	       system as an integer or the atom <c>unknown</c> if the
-	       emulator wasn't able to detect any.
+            <p>Returns the detected number of logical processors configured
+	       on the system. The return value is either an integer, or
+	       the atom <c>unknown</c> if the emulator wasn't able to
+	       detect logical processors configured.
+	    </p>
+          </item>
+	  <tag><marker id="logical_processors_available"><c>logical_processors_available</c></marker></tag>
+          <item>
+            <p>Returns the detected number of logical processors available to
+	       the Erlang runtime system. The return value is either an
+	       integer, or the atom <c>unknown</c> if the emulator wasn't
+	       able to detect logical processors available. The number
+	       of logical processors available is less than or equal to
+	       the number of <seealso marker="#logical_processors_online">logical
+	       processors online</seealso>.
+	    </p>
+          </item>
+	  <tag><marker id="logical_processors_online"><c>logical_processors_online</c></marker></tag>
+          <item>
+            <p>Returns the detected number of logical processors online on
+	       the system. The return value is either an integer,
+	       or the atom <c>unknown</c> if the emulator wasn't able to
+	       detect logical processors online. The number of logical
+	       processors online is less than or equal to the number of
+	       <seealso marker="#logical_processors">logical processors
+	       configured</seealso>.
 	    </p>
           </item>
           <tag><c>machine</c></tag>
@@ -5936,6 +5959,26 @@ true</pre>
               <c>get_tcw</c> in "Match Specifications in Erlang",
               <seealso marker="erts:match_spec#get_tcw">ERTS User's Guide</seealso>.</p>
           </item>
+          <tag><marker id="update_cpu_info"><c>update_cpu_info</c></marker></tag>
+          <item>
+            <p>The runtime system rereads the CPU information available and
+	       updates its internally stored information about the
+	       <seealso marker="#system_info_cpu_topology_detected">detected CPU
+	       topology</seealso> and the amount of logical processors
+	       <seealso marker="#logical_processors">configured</seealso>,
+	       <seealso marker="#logical_processors_online">online</seealso>, and
+	       <seealso marker="#logical_processors_available">available</seealso>.
+	       If the CPU information has changed since the last time it was read,
+	       the atom <c>changed</c> is returned; otherwise, the atom
+	       <c>unchanged</c> is returned. If the CPU information has changed
+	       you probably want to
+	       <seealso marker="#system_flag_schedulers_online">adjust the amount
+	       of schedulers online</seealso>. You typically want to have as
+	       many schedulers online as
+	       <seealso marker="#logical_processors_available">logical processors
+	       available</seealso>.
+	    </p>
+          </item>
           <tag><marker id="system_info_version"><c>version</c></marker></tag>
           <item>
             <p>Returns a string containing the version number of the
diff --git a/erts/emulator/beam/erl_bif_info.c b/erts/emulator/beam/erl_bif_info.c
index 5128776c47..d5ae3d2174 100644
--- a/erts/emulator/beam/erl_bif_info.c
+++ b/erts/emulator/beam/erl_bif_info.c
@@ -2316,6 +2316,15 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     } else if (ERTS_IS_ATOM_STR("cpu_topology", BIF_ARG_1)) {
 	res = erts_get_cpu_topology_term(BIF_P, am_used);
 	BIF_TRAP1(erts_format_cpu_topology_trap, BIF_P, res);
+    } else if (ERTS_IS_ATOM_STR("update_cpu_info", BIF_ARG_1)) {
+	if (erts_update_cpu_info()) {
+	    ERTS_DECL_AM(changed);
+	    BIF_RET(AM_changed);
+	}
+	else {
+	    ERTS_DECL_AM(unchanged);
+	    BIF_RET(AM_unchanged);
+	}
 #if defined(__GNUC__) && defined(HAVE_SOLARIS_SPARC_PERFMON)
     } else if (ERTS_IS_ATOM_STR("ultrasparc_read_tick1", BIF_ARG_1)) {
 	register unsigned high asm("%l0");
@@ -2387,7 +2396,10 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
     }
     /* Arguments that are unusual follow ... */
     else if (ERTS_IS_ATOM_STR("logical_processors", BIF_ARG_1)) {
-	int no = erts_get_cpu_configured(erts_cpuinfo);
+	int no;
+	erts_smp_rwmtx_rlock(&erts_cpu_bind_rwmtx);
+	no = erts_get_cpu_configured(erts_cpuinfo);
+	erts_smp_rwmtx_runlock(&erts_cpu_bind_rwmtx);
 	if (no > 0)
 	    BIF_RET(make_small((Uint) no));
 	else {
@@ -2396,7 +2408,10 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	}
     }
     else if (ERTS_IS_ATOM_STR("logical_processors_online", BIF_ARG_1)) {
-	int no = erts_get_cpu_online(erts_cpuinfo);
+	int no;
+	erts_smp_rwmtx_rlock(&erts_cpu_bind_rwmtx);
+	no = erts_get_cpu_online(erts_cpuinfo);
+	erts_smp_rwmtx_runlock(&erts_cpu_bind_rwmtx);
 	if (no > 0)
 	    BIF_RET(make_small((Uint) no));
 	else {
@@ -2405,7 +2420,10 @@ BIF_RETTYPE system_info_1(BIF_ALIST_1)
 	}
     }
     else if (ERTS_IS_ATOM_STR("logical_processors_available", BIF_ARG_1)) {
-	int no = erts_get_cpu_available(erts_cpuinfo);
+	int no;
+	erts_smp_rwmtx_rlock(&erts_cpu_bind_rwmtx);
+	no = erts_get_cpu_available(erts_cpuinfo);
+	erts_smp_rwmtx_runlock(&erts_cpu_bind_rwmtx);
 	if (no > 0)
 	    BIF_RET(make_small((Uint) no));
 	else {
diff --git a/erts/emulator/beam/erl_process.c b/erts/emulator/beam/erl_process.c
index a644520442..457e283034 100644
--- a/erts/emulator/beam/erl_process.c
+++ b/erts/emulator/beam/erl_process.c
@@ -3962,7 +3962,7 @@ check_cpu_bind(ErtsSchedulerData *esdp)
 		goto unbind;
 	}
     }
-    else if (cpu_id < 0 && scheduler2cpu_map[esdp->no].bound_id >= 0) {
+    else if (cpu_id < 0) /* && scheduler2cpu_map[esdp->no].bound_id >= 0) */ {
     unbind:
 	/* Get rid of old binding */
 	res = erts_unbind_from_cpu(erts_cpuinfo);
@@ -5521,6 +5521,39 @@ late_cpu_bind_init(void)
     }
 }
 
+int
+erts_update_cpu_info(void)
+{
+    int changed;
+    erts_smp_rwmtx_rwlock(&erts_cpu_bind_rwmtx);
+    changed = erts_cpu_info_update(erts_cpuinfo);
+    if (changed) {
+	erts_cpu_topology_t *cpudata;
+	int cpudata_size;
+	erts_free(ERTS_ALC_T_CPUDATA, system_cpudata);
+
+	system_cpudata_size = erts_get_cpu_topology_size(erts_cpuinfo);
+	system_cpudata = erts_alloc(ERTS_ALC_T_CPUDATA,
+				    (sizeof(erts_cpu_topology_t)
+				     * system_cpudata_size));
+
+	if (!erts_get_cpu_topology(erts_cpuinfo, system_cpudata)
+	    || ERTS_INIT_CPU_TOPOLOGY_OK != verify_topology(system_cpudata,
+							    system_cpudata_size)) {
+	    erts_free(ERTS_ALC_T_CPUDATA, system_cpudata);
+	    system_cpudata = NULL;
+	    system_cpudata_size = 0;
+	}
+
+	create_tmp_cpu_topology_copy(&cpudata, &cpudata_size);
+	ASSERT(cpudata);
+	signal_schedulers_bind_change(cpudata, cpudata_size);
+	destroy_tmp_cpu_topology_copy(cpudata);
+    }
+    erts_smp_rwmtx_rwunlock(&erts_cpu_bind_rwmtx);
+    return changed;
+}
+
 #ifdef ERTS_SMP
 
 static void
diff --git a/erts/emulator/beam/erl_process.h b/erts/emulator/beam/erl_process.h
index c3fef6d38e..0cc4a715ad 100644
--- a/erts/emulator/beam/erl_process.h
+++ b/erts/emulator/beam/erl_process.h
@@ -1025,6 +1025,7 @@ int erts_init_scheduler_bind_type(char *how);
 #define ERTS_INIT_CPU_TOPOLOGY_MISSING			9
 
 int erts_init_cpu_topology(char *topology_str);
+int erts_update_cpu_info(void);
 
 void erts_pre_init_process(void);
 void erts_late_init_process(void);
diff --git a/erts/include/internal/erl_misc_utils.h b/erts/include/internal/erl_misc_utils.h
index 6b875ff824..dda2cab5c6 100644
--- a/erts/include/internal/erl_misc_utils.h
+++ b/erts/include/internal/erl_misc_utils.h
@@ -1,7 +1,7 @@
 /*
  * %CopyrightBegin%
  * 
- * Copyright Ericsson AB 2006-2009. All Rights Reserved.
+ * Copyright Ericsson AB 2006-2010. All Rights Reserved.
  * 
  * The contents of this file are subject to the Erlang Public License,
  * Version 1.1, (the "License"); you may not use this file except in
@@ -34,7 +34,7 @@ typedef struct {
 
 erts_cpu_info_t *erts_cpu_info_create(void);
 void erts_cpu_info_destroy(erts_cpu_info_t *cpuinfo);
-void erts_cpu_info_update(erts_cpu_info_t *cpuinfo);
+int erts_cpu_info_update(erts_cpu_info_t *cpuinfo);
 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 d2ef7140a5..6346fe361d 100644
--- a/erts/lib_src/common/erl_misc_utils.c
+++ b/erts/lib_src/common/erl_misc_utils.c
@@ -62,10 +62,10 @@
 #if defined(HAVE_SCHED_xETAFFINITY)
 #  include <sched.h>
 #  define ERTS_HAVE_MISC_UTIL_AFFINITY_MASK__
-#define ERTS_MU_GET_PROC_AFFINITY__(CPUINFOP)				\
+#define ERTS_MU_GET_PROC_AFFINITY__(CPUINFOP, CPUSET)			\
      (sched_getaffinity((CPUINFOP)->pid,				\
 			sizeof(cpu_set_t),				\
-			&(CPUINFOP)->cpuset) != 0 ? -errno : 0)
+			(CPUSET)) != 0 ? -errno : 0)
 #define ERTS_MU_SET_THR_AFFINITY__(SETP)				\
      (sched_setaffinity(0, sizeof(cpu_set_t), (SETP)) != 0 ? -errno : 0)
 #elif defined(__WIN32__)
@@ -99,6 +99,26 @@
 
 static int read_topology(erts_cpu_info_t *cpuinfo);
 
+#if defined(ERTS_HAVE_MISC_UTIL_AFFINITY_MASK__)
+static int
+cpu_sets_are_eq(cpu_set_t *x, cpu_set_t *y)
+{
+    int i;
+    for (i = 0; i < CPU_SETSIZE; i++) {
+	if (CPU_ISSET(i, x)) {
+	    if (!CPU_ISSET(i, y))
+		return 0;
+	}
+	else {
+	    if (CPU_ISSET(i, y))
+		return 0;
+	}
+    }
+    return 1;
+}
+
+#endif
+
 int
 erts_milli_sleep(long ms)
 {
@@ -137,15 +157,15 @@ struct erts_cpu_info_t_ {
 #if defined(__WIN32__)
 
 static __forceinline int
-get_proc_affinity(erts_cpu_info_t *cpuinfo)
+get_proc_affinity(erts_cpu_info_t *cpuinfo, cpu_set_t *cpuset)
 {
     DWORD pamask, samask;
     if (GetProcessAffinityMask(GetCurrentProcess(), &pamask, &samask)) {
-	cpuinfo->cpuset = (cpu_set_t) pamask;
+	*cpuset = (cpu_set_t) pamask;
 	return 0;
     }
     else {
-	cpuinfo->cpuset = (cpu_set_t) 0;
+	*cpuset = (cpu_set_t) 0;
 	return -erts_get_last_win_errno();
     }
 }
@@ -179,6 +199,9 @@ erts_cpu_info_create(void)
 #endif
     cpuinfo->topology_size = 0;
     cpuinfo->topology = NULL;
+    cpuinfo->configured = -1;
+    cpuinfo->online = -1;
+    cpuinfo->available = -1;
     erts_cpu_info_update(cpuinfo);
     return cpuinfo;
 }
@@ -203,34 +226,40 @@ erts_cpu_info_destroy(erts_cpu_info_t *cpuinfo)
     }
 }
 
-void
+int
 erts_cpu_info_update(erts_cpu_info_t *cpuinfo)
 {
-    cpuinfo->configured = 0;
-    cpuinfo->online = 0;
-    cpuinfo->available = 0;
+    int changed = 0;
+    int configured = 0;
+    int online = 0;
+    int available = 0;
+    erts_cpu_topology_t *old_topology;
+    int old_topology_size;
+#if defined(ERTS_HAVE_MISC_UTIL_AFFINITY_MASK__)
+    cpu_set_t cpuset;
+#endif
 
 #ifdef __WIN32__
     {
 	int i;
 	SYSTEM_INFO sys_info;
 	GetSystemInfo(&sys_info);
-	cpuinfo->configured = (int) sys_info.dwNumberOfProcessors;
+	configured = (int) sys_info.dwNumberOfProcessors;
 	for (i = 0; i < sizeof(DWORD)*8; i++)
 	    if (sys_info.dwActiveProcessorMask & (((DWORD) 1) << i))
-		cpuinfo->online++;
+		online++;
     }
 #elif !defined(NO_SYSCONF) && (defined(_SC_NPROCESSORS_CONF) \
 			       || defined(_SC_NPROCESSORS_ONLN))
 #ifdef _SC_NPROCESSORS_CONF
-    cpuinfo->configured = (int) sysconf(_SC_NPROCESSORS_CONF);
-    if (cpuinfo->configured < 0)
-	cpuinfo->configured = 0;
+    configured = (int) sysconf(_SC_NPROCESSORS_CONF);
+    if (configured < 0)
+	configured = 0;
 #endif
 #ifdef _SC_NPROCESSORS_ONLN
-    cpuinfo->online = (int) sysconf(_SC_NPROCESSORS_ONLN);
-    if (cpuinfo->online < 0)
-	cpuinfo->online = 0;
+    online = (int) sysconf(_SC_NPROCESSORS_ONLN);
+    if (online < 0)
+	online = 0;
 #endif
 #elif defined(HAVE_SYS_SYSCTL_H) && defined(CTL_HW) && (defined(HW_NCPU) \
 							|| defined(HW_AVAILCPU))
@@ -242,71 +271,138 @@ erts_cpu_info_update(erts_cpu_info_t *cpuinfo)
 	len = sizeof(int);
 	mib[0] = CTL_HW;
 	mib[1] = HW_NCPU;
-	if (sysctl(&mib[0], 2, &cpuinfo->configured, &len, NULL, 0) < 0)
-	    cpuinfo->configured = 0;
+	if (sysctl(&mib[0], 2, &configured, &len, NULL, 0) < 0)
+	    configured = 0;
 #endif
 #ifdef HW_AVAILCPU
 	len = sizeof(int);
 	mib[0] = CTL_HW;
 	mib[1] = HW_AVAILCPU;
-	if (sysctl(&mib[0], 2, &cpuinfo->online, &len, NULL, 0) < 0)
-	    cpuinfo->online = 0;
+	if (sysctl(&mib[0], 2, &online, &len, NULL, 0) < 0)
+	    online = 0;
 #endif
     }
 #endif
 
-    if (cpuinfo->online > cpuinfo->configured)
-	cpuinfo->online = cpuinfo->configured;
+    if (online > configured)
+	online = configured;
+
+    if (cpuinfo->configured != configured)
+	changed = 1;
+    if (cpuinfo->online != online)
+	changed = 1;
 
 #if defined(ERTS_HAVE_MISC_UTIL_AFFINITY_MASK__)
-    if (ERTS_MU_GET_PROC_AFFINITY__(cpuinfo) == 0) {
-	int i, c, cn, si;
-	c = cn = 0;
-	si = sizeof(cpuinfo->affinity_str_buf) - 1;
-	cpuinfo->affinity_str_buf[si] = '\0';
-	for (i = 0; i < CPU_SETSIZE; i++) {
-	    if (CPU_ISSET(i, &cpuinfo->cpuset)) {
-		c |= 1 << cn;
-		cpuinfo->available++;
+    if (ERTS_MU_GET_PROC_AFFINITY__(cpuinfo, &cpuset) == 0) {
+	if (!changed && !cpu_sets_are_eq(&cpuset, &cpuinfo->cpuset))
+	    changed = 1;
+
+	if (!changed)
+	    available = cpuinfo->available;
+	else {
+	    int i, c, cn, si;
+
+	    memcpy((void *) &cpuinfo->cpuset,
+		   (void *) &cpuset,
+		   sizeof(cpu_set_t));
+
+	    c = cn = 0;
+	    si = sizeof(cpuinfo->affinity_str_buf) - 1;
+	    cpuinfo->affinity_str_buf[si] = '\0';
+	    for (i = 0; i < CPU_SETSIZE; i++) {
+		if (CPU_ISSET(i, &cpuinfo->cpuset)) {
+		    c |= 1 << cn;
+		    available++;
+		}
+		cn++;
+		if (cn == 4) {
+		    cpuinfo->affinity_str_buf[--si] = (c < 10
+						       ? '0' + c
+						       : 'A' + c - 10);
+		    c = cn = 0;
+		}
 	    }
-	    cn++;
-	    if (cn == 4) {
+	    if (c)
 		cpuinfo->affinity_str_buf[--si] = (c < 10
 						   ? '0' + c
 						   : 'A' + c - 10);
-		c = cn = 0;
-	    }
+	    while (cpuinfo->affinity_str_buf[si] == '0')
+		si++;
+	    cpuinfo->affinity_str = &cpuinfo->affinity_str_buf[si];
 	}
-	if (c)
-	    cpuinfo->affinity_str_buf[--si] = (c < 10
-					       ? '0' + c
-					       : 'A' + c - 10);
-	while (cpuinfo->affinity_str_buf[si] == '0')
-	    si++;
-	cpuinfo->affinity_str = &cpuinfo->affinity_str_buf[si];
     }
 #elif defined(HAVE_PSET_INFO)
     {
-	uint_t numcpus = cpuinfo->configured;
-	if (cpuinfo->cpuids)
-	    free(cpuinfo->cpuids);
-	cpuinfo->cpuids = malloc(sizeof(processorid_t)*numcpus);
-	if (cpuinfo->cpuids) {
-	    if (pset_info(PS_MYID, NULL, &numcpus, &cpuinfo->cpuids) == 0)
-		cpuinfo->available = (int) numcpus;
-	    if (cpuinfo->available < 0) {
-		free(cpuinfo->cpuid);
-		cpuinfo->available = 0;
+	processorid_t *cpuids;
+	uint_t numcpus = configured;
+	cpuids = malloc(sizeof(processorid_t)*numcpus);
+	if (cpuids) {
+	    if (pset_info(PS_MYID, NULL, &numcpus, &cpuids) == 0)
+		available = (int) numcpus;
+	    if (available < 0) {
+		free(cpuids);
+		cpuids = NULL;
+		available = 0;
 	    }
 	}
+	if (!cpuids) {
+	    if (cpuinfo->cpuids)
+		changed = 1;
+	}
+	else {
+	    if (cpuinfo->cpuids)
+		changed = 1;
+	    if (memcmp((void *) cpuinfo->cpuids,
+		       (void *) cpuids,
+		       sizeof(processorid_t)*numcpus) != 0)
+		changed = 1;
+
+	}
+	if (!changed) {
+	    if (cpuids)
+		free(cpuids);
+	}
+	else {
+	    if (cpuinfo->cpuids)
+		free(cpuinfo->cpuids);
+	    cpuinfo->cpuids = cpuids;
+	}
     }
 #endif
 
-    if (cpuinfo->available > cpuinfo->online)
-	cpuinfo->available = cpuinfo->online;
+    if (available > online)
+	available = online;
+
+    if (cpuinfo->available != available)
+	changed = 1;
+
+    cpuinfo->configured = configured;
+    cpuinfo->online = online;
+    cpuinfo->available = available;
+
+    old_topology = cpuinfo->topology;
+    old_topology_size = cpuinfo->topology_size;
+    cpuinfo->topology = NULL;
 
     read_topology(cpuinfo);
 
+    if (cpuinfo->topology_size != old_topology_size
+	|| (old_topology_size != 0
+	    && memcmp((void *) cpuinfo->topology,
+		      (void *) old_topology,
+		      (sizeof(erts_cpu_topology_t)
+		       * old_topology_size)) != 0)) {
+	changed = 1;
+	if (old_topology)
+	    free(old_topology);
+    }
+    else {
+	if (cpuinfo->topology)
+	    free(cpuinfo->topology);
+	cpuinfo->topology = old_topology;
+    }
+
+    return changed;
 }
 
 int
@@ -641,9 +737,6 @@ read_topology(erts_cpu_info_t *cpuinfo)
 
     errno = 0;
 
-    if (cpuinfo->topology)
-	free(cpuinfo->topology);
-
     if (cpuinfo->configured < 1)
 	goto error;
 
@@ -896,9 +989,6 @@ read_topology(erts_cpu_info_t *cpuinfo)
 
     errno = 0;
 
-    if (cpuinfo->topology)
-	free(cpuinfo->topology);
-
     if (cpuinfo->configured < 1)
 	goto error;