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 07F86286881; Tue, 26 Aug 2025 14:36:02 +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=1756218962; cv=none; b=CxK+AolC+UN42V5YRILI18ezX0j3XR0S4aj7xE5FlBYOej1P8OMum/y66ihED4gfO559eUW1rxUyknbIhyPYZpLvKcuecyIUO8/DFDX9EOAJ4zKwnrZDuXE+G4GJAP50ctkemWAZJ/IorJ2J590is6pkgPqm7wFhseY/SHmU1tQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756218962; c=relaxed/simple; bh=Dh4Zifi5vWlExY/CyfDSZISCYXpSOdVYS8tRxWpbspU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ciAw7ZTRV41E0thEu+vrC0x9STRAwxbZJ6yg8caHyZSHU4pnbIYRkaM06x/5Sv7sSfyy6Ou/kE/Gh7Isf0bCESfs4LDrh5oSzxfSQC9AOcA8xgRyAoMkqDjZKBgoLe+Y+yNakznTKCh2JgGY6zyfvt43NFa/H6t38bageu66L0A= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=JU2l0Ylx; 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="JU2l0Ylx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8FC08C4CEF1; Tue, 26 Aug 2025 14:36:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1756218961; bh=Dh4Zifi5vWlExY/CyfDSZISCYXpSOdVYS8tRxWpbspU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=JU2l0Ylx3Bukpw7GMSJfkpaMHg8ag+4EUzU2QIs1WqY2kOo/ztpiur51RZEV5USn6 +zYtZEhJzvX3JOF1jpf8/YuH87AYQDYsRnOqaM+bT4nyaPAiGKlExWbKGvPvJtTLRt sQ1AA4Ij1kW9bSvbQ31FAJ7euUMVOqJ+bkl10uOU= 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 5.4 201/403] pm: cpupower: Fix the snapshot-order of tsc,mperf, clock in mperf_stop() Date: Tue, 26 Aug 2025 13:08:47 +0200 Message-ID: <20250826110912.412304079@linuxfoundation.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250826110905.607690791@linuxfoundation.org> References: <20250826110905.607690791@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 5.4-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 0e8c0b879d4b..09c606760464 100644 --- a/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c +++ b/tools/power/cpupower/utils/idle_monitor/mperf_monitor.c @@ -201,9 +201,9 @@ 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