From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B00B6321F56; Mon, 18 Aug 2025 13:24:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755523462; cv=none; b=RYEKWzzqne8nRNIRCrx8bOAEYGoTzTi4yishuWBywA1ZDoJCtst+VCZs5RLK5K9TJKt6uULNa+2Xj6x4TcEAxK1vA45MnT8gDAktQwvD1B+rpNcQMQIH/AmgEC0DvIOZKB089DziDc3i84iHBg/mMSdIELSWr2pOgILVkKBkJU0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755523462; c=relaxed/simple; bh=AXoz0UBU1wMnMabt9I+4TRFyLvg5zkLv9cGtLQDRSmI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jWQpNxT0xBOX2VD5BMk/5wcitJkJyh7QMS2+JTYyHwu6pTNoGZdsdEabhPTq/+18vx60BuSch/mqk7V/eipqP7rLkuu1b2kLZH2RONqqr7gRflFG+7lUyBtNr1/nMY6rvVrD9K7OkQ/uRiKm6fi1O/MwOQ84AMbT2z/lvCNH8xU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=slnn8lIE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="slnn8lIE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 33845C4CEEB; Mon, 18 Aug 2025 13:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1755523462; bh=AXoz0UBU1wMnMabt9I+4TRFyLvg5zkLv9cGtLQDRSmI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=slnn8lIE6KT+YqMkhPmpA2UxwBpqRdui5qw3SiHncuSozxUD6nvtTISZEfblJQaN2 1VNhEJdlXjOR2EVA8ZA4BN9OQpksd4xIyjl13EbEwfIO0eb1gFA/fK7OvX79vLQrdb sWQhLV0af5whf8HOrGyeyXeuno/6phSL/CTGFt4Q= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Gautham R. Shenoy" , Shuah Khan , Sasha Levin Subject: [PATCH 6.15 178/515] pm: cpupower: Fix the snapshot-order of tsc,mperf, clock in mperf_stop() Date: Mon, 18 Aug 2025 14:42:44 +0200 Message-ID: <20250818124505.218947102@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250818124458.334548733@linuxfoundation.org> References: <20250818124458.334548733@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Gautham R. Shenoy [ Upstream commit cda7ac8ce7de84cf32a3871ba5f318aa3b79381e ] In the function mperf_start(), mperf_monitor snapshots the time, tsc and finally the aperf,mperf MSRs. However, this order of snapshotting in is reversed in mperf_stop(). As a result, the C0 residency (which is computed as delta_mperf * 100 / delta_tsc) is under-reported on CPUs that is 100% busy. Fix this by snapshotting time, tsc and then aperf,mperf in mperf_stop() in the same order as in mperf_start(). Link: https://lore.kernel.org/r/20250612122355.19629-2-gautham.shenoy@amd.com Signed-off-by: Gautham R. Shenoy Signed-off-by: Shuah Khan Signed-off-by: Sasha Levin --- tools/power/cpupower/utils/idle_monitor/mperf_monitor.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c index 73b6b10cbdd2..5ae02c3d5b64 100644 --- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c +++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c @@ -240,9 +240,9 @@ static int mperf_stop(void) int cpu; for (cpu = 0; cpu < cpu_count; cpu++) { - mperf_measure_stats(cpu); - mperf_get_tsc(&tsc_at_measure_end[cpu]); clock_gettime(CLOCK_REALTIME, &time_end[cpu]); + mperf_get_tsc(&tsc_at_measure_end[cpu]); + mperf_measure_stats(cpu); } return 0; -- 2.39.5