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Message-ID: <aSi6uGZdIqxLuyhz@google.com>
Date: Thu, 27 Nov 2025 12:55:20 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Ian Rogers <irogers@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
James Clark <james.clark@...aro.org>,
Collin Funk <collin.funk1@...il.com>,
Dmitry Vyukov <dvyukov@...gle.com>, Andi Kleen <ak@...ux.intel.com>,
Thomas Falcon <thomas.falcon@...el.com>, Leo Yan <leo.yan@....com>,
Yicong Yang <yangyicong@...ilicon.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Masami Hiramatsu (Google)" <mhiramat@...nel.org>,
Stephen Brennan <stephen.s.brennan@...cle.com>,
Haibo Xu <haibo1.xu@...el.com>, linux-kernel@...r.kernel.org,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH v1 17/17] perf test kvm: Add some basic perf kvm test
coverage
On Thu, Nov 27, 2025 at 03:53:13AM -0800, Ian Rogers wrote:
> On Tue, Nov 25, 2025 at 11:21 PM Namhyung Kim <namhyung@...nel.org> wrote:
> >
> > On Sat, Nov 22, 2025 at 12:19:29AM -0800, Ian Rogers wrote:
> > > Setup qemu with KVM then run kvm stat and some host
> > > recording/reporting/build-id tests.
> > >
> > > Signed-off-by: Ian Rogers <irogers@...gle.com>
> > > ---
> > > tools/perf/tests/shell/kvm.sh | 154 ++++++++++++++++++++++++++++++++++
> > > 1 file changed, 154 insertions(+)
> > > create mode 100755 tools/perf/tests/shell/kvm.sh
> > >
> > > diff --git a/tools/perf/tests/shell/kvm.sh b/tools/perf/tests/shell/kvm.sh
> > > new file mode 100755
> > > index 000000000000..2fafde1a29cc
> > > --- /dev/null
> > > +++ b/tools/perf/tests/shell/kvm.sh
> > > @@ -0,0 +1,154 @@
> > > +#!/bin/bash
> > > +# perf kvm tests
> > > +# SPDX-License-Identifier: GPL-2.0
> > > +
> > > +set -e
> > > +
> > > +err=0
> > > +perfdata=$(mktemp /tmp/__perf_kvm_test.perf.data.XXXXX)
> > > +qemu_pid_file=$(mktemp /tmp/__perf_kvm_test.qemu.pid.XXXXX)
> > > +
> > > +cleanup() {
> > > + rm -f "${perfdata}"
> > > + if [ -f "${qemu_pid_file}" ]; then
> > > + if [ -s "${qemu_pid_file}" ]; then
> > > + qemu_pid=$(cat "${qemu_pid_file}")
> > > + if [ -n "${qemu_pid}" ]; then
> > > + kill "${qemu_pid}" 2>/dev/null || true
> > > + fi
> > > + fi
> > > + rm -f "${qemu_pid_file}"
> > > + fi
> > > + trap - EXIT TERM INT
> > > +}
> > > +
> > > +trap_cleanup() {
> > > + echo "Unexpected signal in ${FUNCNAME[1]}"
> > > + cleanup
> > > + exit 1
> > > +}
> > > +trap trap_cleanup EXIT TERM INT
> > > +
> > > +skip() {
> > > + echo "Skip: $1"
> > > + cleanup
> > > + exit 2
> > > +}
> > > +
> > > +test_kvm_stat() {
> > > + echo "Testing perf kvm stat"
> > > +
> > > + echo "Recording kvm events for pid ${qemu_pid}..."
> > > + if ! perf kvm stat record -p "${qemu_pid}" -o "${perfdata}" sleep 1; then
> > > + echo "Failed to record kvm events"
> > > + err=1
> > > + return
> > > + fi
> > > +
> > > + echo "Reporting kvm events..."
> > > + if ! perf kvm -i "${perfdata}" stat report 2>&1 | grep -q "VM-EXIT"; then
> > > + echo "Failed to find VM-EXIT in report"
> > > + perf kvm -i "${perfdata}" stat report 2>&1
> > > + err=1
> > > + return
> > > + fi
> > > +
> > > + echo "perf kvm stat test [Success]"
> > > +}
> > > +
> > > +test_kvm_record_report() {
> > > + echo "Testing perf kvm record/report"
> > > +
> > > + echo "Recording kvm profile for pid ${qemu_pid}..."
> > > + # Use --host to avoid needing guest symbols/mounts for this simple test
> > > + # We just want to verify the command runs and produces data
> > > + # We run in background and kill it because 'perf kvm record' appends options
> > > + # after the command, which breaks 'sleep' (e.g. it gets '-e cycles').
> > > + perf kvm --host record -p "${qemu_pid}" -o "${perfdata}" &
> > > + rec_pid=$!
> > > + sleep 1
> > > + kill -INT "${rec_pid}"
> > > + wait "${rec_pid}" || true
> > > +
> > > + echo "Reporting kvm profile..."
> > > + # Check for some standard output from report
> > > + if ! perf kvm -i "${perfdata}" report --stdio 2>&1 | grep -q "Event count"; then
> > > + echo "Failed to report kvm profile"
> > > + perf kvm -i "${perfdata}" report --stdio 2>&1
> > > + err=1
> > > + return
> > > + fi
> > > +
> > > + echo "perf kvm record/report test [Success]"
> > > +}
> > > +
> > > +test_kvm_buildid_list() {
> > > + echo "Testing perf kvm buildid-list"
> > > +
> > > + # We reuse the perf.data from the previous record test
> > > + if ! perf kvm --host -i "${perfdata}" buildid-list 2>&1 | grep -q "."; then
> > > + echo "Failed to list buildids"
> > > + perf kvm --host -i "${perfdata}" buildid-list 2>&1
> > > + err=1
> > > + return
> > > + fi
> > > +
> > > + echo "perf kvm buildid-list test [Success]"
> > > +}
> > > +
> > > +setup_qemu() {
> > > + # Find qemu
> > > + if [ "$(uname -m)" = "x86_64" ]; then
> > > + qemu="qemu-system-x86_64"
> > > + elif [ "$(uname -m)" = "aarch64" ]; then
> > > + qemu="qemu-system-aarch64"
> > > + elif [ "$(uname -m)" = "s390x" ]; then
> > > + qemu="qemu-system-s390x"
> > > + elif [ "$(uname -m)" = "ppc64le" ]; then
> > > + qemu="qemu-system-ppc64"
> > > + else
> > > + qemu="qemu-system-$(uname -m)"
> > > + fi
> > > +
> > > + if ! which -s "$qemu"; then
> > > + skip "$qemu not found"
> > > + fi
> > > +
> > > + if [ ! -r /dev/kvm ] || [ ! -w /dev/kvm ]; then
> > > + skip "/dev/kvm not accessible"
> > > + fi
> > > +
> > > + if ! perf kvm stat record -a sleep 0.01 >/dev/null 2>&1; then
> > > + skip "No permission to record kvm events"
> > > + fi
> > > +
> > > + echo "Starting $qemu..."
> > > + # Start qemu in background, detached, with pidfile
> > > + # We use -display none -daemonize and a monitor to keep it alive/controllable if needed
> > > + # We don't need a real kernel, just KVM active.
> > > + if ! $qemu -enable-kvm -display none -daemonize -pidfile "${qemu_pid_file}" -monitor none; then
> >
> > What is running in the guest?
>
> Nothing. As no kernel or storage image were provided the guest should
> be waiting at the bios similar to if you booted a PC with no storage
> in it. I just wanted something quick and dirty to give the basic perf
> kvm command a simple work out for the sake of testing coverage.
Ok, it'd be fine as long as perf can get some samples in the guest.
Thanks,
Namhyung
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