linux-kernel - [tip: core/rcu] torture: Hoist calls to lscpu to higher-level kvm.sh script

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-ID: <157994897084.396.6588052021936782800.tip-bot2@tip-bot2>
Date:   Sat, 25 Jan 2020 10:42:50 -0000
From:   "tip-bot2 for Paul E. McKenney" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Paul E. McKenney" <paulmck@...nel.org>, x86 <x86@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: [tip: core/rcu] torture: Hoist calls to lscpu to higher-level kvm.sh script

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     b22eb7cefb9d31cf862542f9cef90f97c0294842
Gitweb:        https://git.kernel.org/tip/b22eb7cefb9d31cf862542f9cef90f97c0294842
Author:        Paul E. McKenney <paulmck@...nel.org>
AuthorDate:    Mon, 25 Nov 2019 14:33:28 -08:00
Committer:     Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Mon, 09 Dec 2019 13:00:30 -08:00

torture: Hoist calls to lscpu to higher-level kvm.sh script

On some kernels, concurrent calls to the lscpu command result in severe
slowdowns.  For example, on v4.16, a single lscpu invocation takes about
two milliseconds, four concurrent invocations more than two seconds,
and 16 concurrent invocations more than 20 seconds.  Given that the only
goal is to learn the number of CPUs, invoking lscpu but once suffices.
This commit therefore invokes lscpu early in kvm.sh execution, setting
the initial value of the TORTURE_ALLOTED_CPUS environment variable.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh |  7 +---
 tools/testing/selftests/rcutorture/bin/kvm.sh            | 11 +++++--
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
index 1d98992..e035230 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm-test-1-run.sh
@@ -133,11 +133,10 @@ fi
 qemu_args="-enable-kvm -nographic $qemu_args"
 cpu_count=`configNR_CPUS.sh $resdir/ConfigFragment`
 cpu_count=`configfrag_boot_cpus "$boot_args" "$config_template" "$cpu_count"`
-vcpus=`identify_qemu_vcpus`
-if test $cpu_count -gt $vcpus
+if test "$cpu_count" -gt "$TORTURE_ALLOTED_CPUS"
 then
-	echo CPU count limited from $cpu_count to $vcpus | tee -a $resdir/Warnings
-	cpu_count=$vcpus
+	echo CPU count limited from $cpu_count to $TORTURE_ALLOTED_CPUS | tee -a $resdir/Warnings
+	cpu_count=$TORTURE_ALLOTED_CPUS
 fi
 qemu_args="`specify_qemu_cpus "$QEMU" "$qemu_args" "$cpu_count"`"
 
diff --git a/tools/testing/selftests/rcutorture/bin/kvm.sh b/tools/testing/selftests/rcutorture/bin/kvm.sh
index e19151c..78d18ab 100755
--- a/tools/testing/selftests/rcutorture/bin/kvm.sh
+++ b/tools/testing/selftests/rcutorture/bin/kvm.sh
@@ -24,7 +24,9 @@ dur=$((30*60))
 dryrun=""
 KVM="`pwd`/tools/testing/selftests/rcutorture"; export KVM
 PATH=${KVM}/bin:$PATH; export PATH
-TORTURE_ALLOTED_CPUS=""
+. functions.sh
+
+TORTURE_ALLOTED_CPUS="`identify_qemu_vcpus`"
 TORTURE_DEFCONFIG=defconfig
 TORTURE_BOOT_IMAGE=""
 TORTURE_INITRD="$KVM/initrd"; export TORTURE_INITRD
@@ -40,8 +42,6 @@ cpus=0
 ds=`date +%Y.%m.%d-%H:%M:%S`
 jitter="-1"
 
-. functions.sh
-
 usage () {
 	echo "Usage: $scriptname optional arguments:"
 	echo "       --bootargs kernel-boot-arguments"
@@ -93,6 +93,11 @@ do
 		checkarg --cpus "(number)" "$#" "$2" '^[0-9]*$' '^--'
 		cpus=$2
 		TORTURE_ALLOTED_CPUS="$2"
+		max_cpus="`identify_qemu_vcpus`"
+		if test "$TORTURE_ALLOTED_CPUS" -gt "$max_cpus"
+		then
+			TORTURE_ALLOTED_CPUS=$max_cpus
+		fi
 		shift
 		;;
 	--datestamp)