From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.19]) (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 17660245019; Fri, 27 Mar 2026 17:35:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.19 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774632910; cv=none; b=atAGxGq+sfk8VK2n0RowfB0kT3M3Hmljl5/6jN0jsHn7t0OX1sFy3ytUwI8v3vB4DEIY5jLwUUGq7DrOylb2nGW+Z2fSLHzisR0lffOoktLwfjSBXddwpJXM+mGmDW9nfdbaMCi6vALQMgZh5KGHQrKICtECjFLek4FfwiCZBXw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774632910; c=relaxed/simple; bh=g4tN38ZQdvBNUKmLr8XIM93tcq62pCUYXnI/PtosVuI=; h=From:Date:To:cc:Subject:In-Reply-To:Message-ID:References: MIME-Version:Content-Type; b=bBp021pAzG5WVPQA0ikYJd3bq0lxaM1pIkMb+4qPnm4jMvw7+F+/+j9BOrMecgFDjtPLYHGDAJXqcEd9t3uGmmkMUv2H0JEVbOKqeq+LHfn2X0hTvqzobpTA4mLrOOkxo9t5ApJFd5qG9qv3Cne0/QNaRyrMRVFUPUwxY16qEhM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=PvpiscmW; arc=none smtp.client-ip=192.198.163.19 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="PvpiscmW" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1774632909; x=1806168909; h=from:date:to:cc:subject:in-reply-to:message-id: references:mime-version; bh=g4tN38ZQdvBNUKmLr8XIM93tcq62pCUYXnI/PtosVuI=; b=PvpiscmW1Mp192CHBKJc9a4GgZnPvWOvzs3zajvMCxAuxcm4q1yBXGAJ 7tY8CbiY/EiU+p9fDYfV132U0KQegk53oJ3c6UksuAWdqnwH2YFpRTF2Y JzXPgOL65IAsHVLTx2Y7nhBfuO7vBLoDnb3M7a89pWDlFS1g4pXASN/w0 64Y9gLqLQySaWRBREjyvX/QNs6PrlzGmiLy6jV8CbFuVYdxqySFADmGvz HGbYmXLolVaBWGYu9l19UxvSYTF+u/ehNtTPsmDbh0BnWKOsuBf7yLW8J kHfzhjviR/5EJxSvt2vu2Y/kBLjqojYeWJsfHqHYKi4X9eIIgYM8FpUQI Q==; X-CSE-ConnectionGUID: jX732PZoQsyWllJDcfuC8g== X-CSE-MsgGUID: XArEqFOkSUK4V/EMeavopA== X-IronPort-AV: E=McAfee;i="6800,10657,11742"; a="74742671" X-IronPort-AV: E=Sophos;i="6.23,144,1770624000"; d="scan'208";a="74742671" Received: from fmviesa003.fm.intel.com ([10.60.135.143]) by fmvoesa113.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2026 10:34:55 -0700 X-CSE-ConnectionGUID: 98+cuf0TSWCMZEK/kDz0Tw== X-CSE-MsgGUID: kyUtY0oORL+lvJpKHGpK5Q== X-ExtLoop1: 1 Received: from ijarvine-mobl1.ger.corp.intel.com (HELO localhost) ([10.245.244.186]) by fmviesa003-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Mar 2026 10:34:49 -0700 From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= Date: Fri, 27 Mar 2026 19:34:46 +0200 (EET) To: Reinette Chatre cc: shuah@kernel.org, Dave.Martin@arm.com, james.morse@arm.com, tony.luck@intel.com, babu.moger@amd.com, ilpo.jarvinen@linux.intel.com, fenghuay@nvidia.com, peternewman@google.com, zide.chen@intel.com, dapeng1.mi@linux.intel.com, ben.horgan@arm.com, yu.c.chen@intel.com, jason.zeng@intel.com, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev Subject: Re: [PATCH v3 07/10] selftests/resctrl: Raise threshold at which MBM and PMU values are compared In-Reply-To: <1bdca244a899a605c1ddd701a09d6a9d0c242856.1773432891.git.reinette.chatre@intel.com> Message-ID: References: <1bdca244a899a605c1ddd701a09d6a9d0c242856.1773432891.git.reinette.chatre@intel.com> Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323328-263950525-1774632886=:1037" This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-263950525-1774632886=:1037 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: QUOTED-PRINTABLE On Fri, 13 Mar 2026, Reinette Chatre wrote: > commit 501cfdba0a40 ("selftests/resctrl: Do not compare performance Should start with a capital letter. > counters and resctrl at low bandwidth") introduced a threshold under whic= h > memory bandwidth values from MBM and performance counters are not compare= d. > This is needed because MBM and the PMUs do not have an identical view of > memory bandwidth since PMUs can count all memory traffic while MBM does n= ot > count "overhead" (for example RAS) traffic that cannot be attributed to a= n > RMID. As a ratio this difference in view of memory bandwidth is pronounce= d > at low memory bandwidths. >=20 > The 750MiB threshold was chosen arbitrarily after comparisons on differen= t > platforms. Exposed to more platforms after introduction this threshold ha= s > proven to be inadequate. >=20 > Having accurate comparison between performance counters and MBM requires > careful management of system load as well as control of features that > introduce extra memory traffic, for example, patrol scrub. This is not > appropriate for the resctrl selftests that are intended to run on a > variety of systems with various configurations. >=20 > Increase the memory bandwidth threshold under which no comparison is made > between performance counters and MBM. Add additional leniency by increasi= ng > the percentage of difference that will be tolerated between these counts. >=20 > There is no impact to the validity of the resctrl selftests results as a > measure of resctrl subsystem health. >=20 > Signed-off-by: Reinette Chatre > Tested-by: Chen Yu > --- > Changes since v2: > - Add Chen Yu's tag. > --- > tools/testing/selftests/resctrl/mba_test.c | 2 +- > tools/testing/selftests/resctrl/mbm_test.c | 2 +- > tools/testing/selftests/resctrl/resctrl.h | 2 +- > 3 files changed, 3 insertions(+), 3 deletions(-) >=20 > diff --git a/tools/testing/selftests/resctrl/mba_test.c b/tools/testing/s= elftests/resctrl/mba_test.c > index cd4c715b7ffd..39cee9898359 100644 > --- a/tools/testing/selftests/resctrl/mba_test.c > +++ b/tools/testing/selftests/resctrl/mba_test.c > @@ -12,7 +12,7 @@ > =20 > #define RESULT_FILE_NAME=09"result_mba" > #define NUM_OF_RUNS=09=095 > -#define MAX_DIFF_PERCENT=098 > +#define MAX_DIFF_PERCENT=0915 > #define ALLOCATION_MAX=09=09100 > #define ALLOCATION_MIN=09=0910 > #define ALLOCATION_STEP=09=0910 > diff --git a/tools/testing/selftests/resctrl/mbm_test.c b/tools/testing/s= elftests/resctrl/mbm_test.c > index 58201f844740..6dbbc3b76003 100644 > --- a/tools/testing/selftests/resctrl/mbm_test.c > +++ b/tools/testing/selftests/resctrl/mbm_test.c > @@ -11,7 +11,7 @@ > #include "resctrl.h" > =20 > #define RESULT_FILE_NAME=09"result_mbm" > -#define MAX_DIFF_PERCENT=098 > +#define MAX_DIFF_PERCENT=0915 > #define NUM_OF_RUNS=09=095 > =20 > static int > diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/se= lftests/resctrl/resctrl.h > index 7f2ab28be857..3bad2d80c09b 100644 > --- a/tools/testing/selftests/resctrl/resctrl.h > +++ b/tools/testing/selftests/resctrl/resctrl.h > @@ -55,7 +55,7 @@ > * and MBM respectively, for instance generating "overhead" traffic whic= h > * is not counted against any specific RMID. > */ > -#define THROTTLE_THRESHOLD=09750 > +#define THROTTLE_THRESHOLD=092500 > =20 > /* > * fill_buf_param:=09"fill_buf" benchmark parameters >=20 Reviewed-by: Ilpo J=E4rvinen --=20 i. --8323328-263950525-1774632886=:1037--