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), 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.

Co-Authored-By: Ray Bellis <ray@isc.org>
(cherry picked from commit 5a2df8caf5)

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;
 	}
 }