[9.18] chg: usr: Follow the number of CPU set by taskset/cpuset

Administrators may wish to constrain the set of cores that BIND 9 runs on via the 'taskset', 'cpuset' or 'numactl' programs (or equivalent on other O/S).

If the admin has used taskset, the `named` will now follow to automatically use the given number of CPUs rather than the system wide count.

Closes #4884

Backport of MR !9398

Merge branch 'backport-4884-use-cpuset-to-get-number-of-cpus-9.18' into 'bind-9.18'

See merge request isc-projects/bind9!9443

bin/tests/system/Makefile.am

@@ -108,6 +108,7 @@ TESTS =				\
 	checknames		\
 	checkzone		\
 	cookie			\
+	cpu			\
 	database		\
 	dialup			\
 	digdelv			\

bin/tests/system/cpu/clean.sh

@@ -0,0 +1,16 @@
+#!/bin/sh
+
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+set -e
+
+rm -f ./named.run.*

bin/tests/system/cpu/ns1/named.conf.in

@@ -0,0 +1,20 @@
+/*
+ * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+ *
+ * SPDX-License-Identifier: MPL-2.0
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0.  If a copy of the MPL was not distributed with this
+ * file, you can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See the COPYRIGHT file distributed with this work for additional
+ * information regarding copyright ownership.
+ */
+
+options {
+	query-source address 10.53.0.1;
+	port @PORT@;
+	pid-file "named.pid";
+	listen-on { 10.53.0.1; };
+	listen-on-v6 { none; };
+};

bin/tests/system/cpu/prereq.sh

@@ -0,0 +1,21 @@
+#!/bin/sh
+
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+. ../conf.sh
+
+command -v cpuset >/dev/null || command -v numactl >/dev/null || command -v taskset >/dev/null || {
+  echo_i "This test requires cpuset, numactl, or taskset." >&2
+  exit 255
+}
+
+exit 0

bin/tests/system/cpu/setup.sh

@@ -0,0 +1,21 @@
+#!/bin/sh -e
+
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+# shellcheck source=conf.sh
+. ../conf.sh
+
+set -e
+
+$SHELL clean.sh
+
+copy_setports ns1/named.conf.in ns1/named.conf

bin/tests/system/cpu/tests.sh

@@ -0,0 +1,65 @@
+#!/bin/sh
+
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+# shellcheck source=conf.sh
+. ../conf.sh
+
+status=0
+n=0
+
+CPUSET=$(command -v cpuset)
+NUMACTL=$(command -v numactl)
+TASKSET=$(command -v taskset)
+
+cpulist() (
+  if [ -n "$CPUSET" ]; then
+    cpuset -g | head -1 | sed -e "s/.*: //" | tr -s ', ' '\n'
+  elif [ -n "$NUMACTL" ]; then
+    numactl --show | sed -ne 's/^physcpubind: //p' | tr -s ' ' '\n'
+  elif [ -n "$TASKSET" ]; then
+    # shellcheck disable=SC2046
+    seq $(taskset -c -p $$ | sed -e 's/.*: //' | tr -s ' -' ' ')
+  else
+    echo 0
+  fi
+)
+
+cpulimit() (
+  set -x
+  min_cpu="${1}"
+  shift
+  max_cpu="${1}"
+  shift
+
+  if [ -n "$CPUSET" ]; then
+    cpuset -l "${min_cpu}-${max_cpu}" "$@" 2>&1
+  elif [ -n "$NUMACTL" ]; then
+    numactl --physcpubind="${min_cpu}-${max_cpu}" "$@" 2>&1
+  elif [ -n "$TASKSET" ]; then
+    taskset -c "${min_cpu}-${max_cpu}" "$@" 2>&1
+  fi
+)
+
+ret=0
+for cpu in $(cpulist); do
+  n=$((n + 1))
+  echo_i "testing that limiting CPU sets to 0-${cpu} works ($n)"
+  cpulimit 0 "$cpu" "$NAMED" -g >named.run.$n 2>&1 || true
+  ncpus=$(sed -ne 's/.*found \([0-9]*\) CPU.*\([0-9]*\) worker thread.*/\1/p' named.run.$n)
+  [ "$ncpus" -eq "$((cpu + 1))" ] || ret=1
+done
+test "$ret" -eq 0 || echo_i "failed"
+status=$((status + ret))
+
+echo_i "exit status: $status"
+[ $status -eq 0 ] || exit 1

bin/tests/system/cpu/tests_sh_cpu.py

@@ -0,0 +1,14 @@
+# Copyright (C) Internet Systems Consortium, Inc. ("ISC")
+#
+# SPDX-License-Identifier: MPL-2.0
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0.  If a copy of the MPL was not distributed with this
+# file, you can obtain one at https://mozilla.org/MPL/2.0/.
+#
+# See the COPYRIGHT file distributed with this work for additional
+# information regarding copyright ownership.
+
+
+def test_cpu(run_tests_sh):
+    run_tests_sh()

configure.ac

@@ -265,7 +265,8 @@ AS_CASE([$host],
 		  ])
 	])
 
-AC_CHECK_HEADERS([fcntl.h regex.h sys/time.h unistd.h sys/mman.h sys/sockio.h sys/select.h sys/param.h sys/sysctl.h net/if6.h sys/socket.h net/route.h linux/netlink.h linux/rtnetlink.h], [], [],
+AC_CHECK_HEADERS([sys/param.h sys/socket.h])
+AC_CHECK_HEADERS([fcntl.h regex.h sys/time.h unistd.h sys/mman.h sys/sockio.h sys/select.h sys/sysctl.h net/if6.h net/route.h linux/netlink.h linux/rtnetlink.h], [], [],
 		 [$ac_includes_default
 		  #ifdef HAVE_SYS_PARAM_H
 		  # include <sys/param.h>
@@ -532,9 +533,16 @@ AM_CONDITIONAL([HAVE_LIBNGHTTP2], [test -n "$LIBNGHTTP2_LIBS"])
 AC_CHECK_FUNCS([flockfile getc_unlocked])
 
 #
-# Look for sysconf to allow detection of the number of processors.
+# Look for sysconf or other ways to allow detection of the number of processors.
 #
 AC_CHECK_FUNCS([sysconf])
+AC_CHECK_FUNCS(sysconf sched_getaffinity cpuset_getaffinity)
+AC_CHECK_HEADERS([sys/cpuset.h], [], [],
+		 [$ac_includes_default
+		  #ifdef HAVE_SYS_PARAM_H
+		  # include <sys/param.h>
+		  #endif
+		 ])
 
 #
 # Do we want to use pthread rwlock?

lib/isc/os.c

@@ -59,17 +59,94 @@ sysctl_ncpus(void) {
 }
 #endif /* if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME) */
 
+#if defined(HAVE_SCHED_GETAFFINITY)
+
+#if defined(HAVE_SCHED_H)
+#include <sched.h>
+#endif
+
+/*
+ * Administrators may wish to constrain the set of cores that BIND runs
+ * on via the 'taskset' or 'numactl' programs (or equivalent on other
+ * O/S), for example to achieve higher (or more stable) performance by
+ * more closely associating threads with individual NIC rx queues. If
+ * the admin has used taskset, it follows that BIND ought to
+ * automatically use the given number of CPUs rather than the system
+ * wide count.
+ */
+static int
+sched_affinity_ncpus(void) {
+	cpu_set_t cpus;
+	int result;
+
+	result = sched_getaffinity(0, sizeof(cpus), &cpus);
+	if (result != -1) {
+#ifdef CPU_COUNT
+		return (CPU_COUNT(&cpus));
+#else
+		int i, n = 0;
+
+		for (i = 0; i < CPU_SETSIZE; ++i) {
+			if (CPU_ISSET(i, &cpus))
+				++n;
+		}
+		return (n);
+#endif
+	}
+	return (0);
+}
+#endif
+
+/*
+ * Affinity detecting variant of sched_affinity_cpus() for FreeBSD
+ */
+
+#if defined(HAVE_SYS_CPUSET_H) && defined(HAVE_CPUSET_GETAFFINITY)
+#include <sys/cpuset.h>
+#include <sys/param.h>
+
+static int
+cpuset_affinity_ncpus(void) {
+	cpuset_t cpus;
+	int result;
+
+	result = cpuset_getaffinity(CPU_LEVEL_WHICH, CPU_WHICH_PID, -1,
+				    sizeof(cpus), &cpus);
+	if (result != -1) {
+		int i, n = 0;
+		for (i = 0; i < CPU_SETSIZE; ++i) {
+			if (CPU_ISSET(i, &cpus))
+				++n;
+		}
+		return (n);
+	}
+	return (0);
+}
+#endif
+
 static void
 ncpus_initialize(void) {
+#if defined(HAVE_SYS_CPUSET_H) && defined(HAVE_CPUSET_GETAFFINITY)
+	if (isc__os_ncpus <= 0) {
+		isc__os_ncpus = cpuset_affinity_ncpus();
+	}
+#endif
+#if defined(HAVE_SCHED_GETAFFINITY)
+	if (isc__os_ncpus <= 0) {
+		isc__os_ncpus = sched_affinity_ncpus();
+	}
+#endif
 #if defined(HAVE_SYSCONF)
-	isc__os_ncpus = sysconf_ncpus();
+	if (isc__os_ncpus <= 0) {
+		isc__os_ncpus = sysconf_ncpus();
+	}
 #endif /* if defined(HAVE_SYSCONF) */
 #if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME)
 	if (isc__os_ncpus <= 0) {
 		isc__os_ncpus = sysctl_ncpus();
 	}
 #endif /* if defined(HAVE_SYS_SYSCTL_H) && defined(HAVE_SYSCTLBYNAME) */
-	if (isc__os_ncpus == 0) {
+	if (isc__os_ncpus <= 0) {
 		isc__os_ncpus = 1;
 	}
 }