From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68FE0C2BB1D for ; Wed, 11 Mar 2020 17:38:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F202B2073E for ; Wed, 11 Mar 2020 17:38:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730571AbgCKRil (ORCPT ); Wed, 11 Mar 2020 13:38:41 -0400 Received: from mga18.intel.com ([134.134.136.126]:22480 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729852AbgCKRil (ORCPT ); Wed, 11 Mar 2020 13:38:41 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Mar 2020 10:38:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,541,1574150400"; d="scan'208";a="261211208" Received: from sai-dev-mach.sc.intel.com ([143.183.140.153]) by orsmga002.jf.intel.com with ESMTP; 11 Mar 2020 10:38:39 -0700 Message-ID: <04c252f59062450e14642fcbef4b85845f6a7427.camel@intel.com> Subject: Re: [PATCH V1 11/13] selftests/resctrl: Change Cache Quality Monitoring (CQM) test From: Sai Praneeth Prakhya To: Reinette Chatre , shuah@kernel.org, linux-kselftest@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, tony.luck@intel.com, babu.moger@amd.com, james.morse@arm.com, ravi.v.shankar@intel.com, fenghua.yu@intel.com, x86@kernel.org, linux-kernel@vger.kernel.org Date: Wed, 11 Mar 2020 10:33:52 -0700 In-Reply-To: References: <26086dda86f062bba4116878a012a553503924b2.1583657204.git.sai.praneeth.prakhya@intel.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.30.5-0ubuntu0.18.10.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Reinette, On Wed, 2020-03-11 at 10:19 -0700, Reinette Chatre wrote: > Hi Sai, > > On 3/10/2020 7:46 PM, Sai Praneeth Prakhya wrote: > > On Tue, 2020-03-10 at 15:18 -0700, Reinette Chatre wrote: > > > On 3/6/2020 7:40 PM, Sai Praneeth Prakhya wrote: > > > > .mum_resctrlfs = 0, > > > > .filename = RESULT_FILE_NAME, > > > > - .mask = ~(long_mask << n) & long_mask, > > > > - .span = cache_size * n / count_of_bits, > > > > .num_of_runs = 0, > > > > - .setup = cqm_setup, > > > > + .setup = cqm_setup > > > > }; > > > > + int ret; > > > > + char schemata[64]; > > > > + unsigned long long_mask; > > > > > > > > - if (strcmp(benchmark_cmd[0], "fill_buf") == 0) > > > > - sprintf(benchmark_cmd[1], "%lu", param.span); > > > > + ret = remount_resctrlfs(1); > > > > + if (ret) > > > > + return ret; > > > > > > Here resctrl is remounted and followed by some changes to the root > > > group's schemata. That is followed by a call to resctrl_val that > > > attempts to remount resctrl again that will undo all the configurations > > > inbetween. > > > > No, it wouldn't because mum_resctrlfs is 0. When resctrl FS is already > > mounted > > and mum_resctrlfs is 0, then remount_resctrlfs() is a noop. > > > > I missed that. Thank you. > > fyi ... when I tried these tests I encountered the following error > related to unmounting: > > [SNIP] > ok Write schema "L3:1=7fff" to resctrl FS > ok Write schema "L3:1=ffff" to resctrl FS > ok Write schema "L3:1=1ffff" to resctrl FS > ok Write schema "L3:1=3ffff" to resctrl FS > # Unable to umount resctrl: Device or resource busy > # Results are displayed in (Bytes) > ok CQM: diff within 5% for mask 1 > # alloc_llc_cache_size: 2883584 > # avg_llc_occu_resc: 2973696 > ok CQM: diff within 5% for mask 3 > [SNIP] > > This seems to originate from resctrl_val() that forces an unmount but if > that fails the error is not propagated. Yes, that's right and it's a good test. I didn't encounter this issue during my testing because I wasn't using resctrl FS from other terminals (I think you were using resctrl FS from other terminal and hence resctrl_test was unable to unmount it). I think the error should not be propagated because unmounting resctrl FS shouldn't stop us from checking the results. If measuring values reports an error then we shouldn't check for results. > > > > diff --git a/tools/testing/selftests/resctrl/resctrl_val.c > > > > b/tools/testing/selftests/resctrl/resctrl_val.c > > > > index 271cb5c976f5..c59fad6cb9b0 100644 > > > > --- a/tools/testing/selftests/resctrl/resctrl_val.c > > > > +++ b/tools/testing/selftests/resctrl/resctrl_val.c > > > > @@ -705,29 +705,21 @@ int resctrl_val(char **benchmark_cmd, struct > > > > resctrl_val_param *param) > > > > goto out; > > > > } > > > > > > > > - /* Give benchmark enough time to fully run */ > > > > - sleep(1); > > > > - > > > > /* Test runs until the callback setup() tells the test to > > > > stop. */ > > > > while (1) { > > > > + ret = param->setup(param); > > > > + if (ret) { > > > > + ret = 0; > > > > + break; > > > > + } > > > > + > > > > + /* Measure vals sleeps for a second */ > > > > if ((strcmp(resctrl_val, "mbm") == 0) || > > > > (strcmp(resctrl_val, "mba") == 0)) { > > > > - ret = param->setup(param); > > > > - if (ret) { > > > > - ret = 0; > > > > - break; > > > > - } > > > > - > > (I refer to the above snippet in my comment below) > > > > > ret = measure_vals(param, &bw_resc_start); > > > > if (ret) > > > > break; > > > > } else if (strcmp(resctrl_val, "cqm") == 0) { > > > > - ret = param->setup(param); > > > > - if (ret) { > > > > - ret = 0; > > > > - break; > > > > - } > > > > - sleep(1); > > > > ret = measure_cache_vals(param, bm_pid); > > > > if (ret) > > > > break; > > > > > > This change affects not just the cache monitoring test. Could this > > > change be extracted into its own patch to be clear what is done here and > > > how it impacts the other tests? > > > > This change shouldn't impact other tests (i.e. CAT) because CAT will not > > call > > resctrl_val(). > > I was referring to the snippet above that seems to impact the "mbm" and > "mba" tests by moving the call to "param->setup" for the them. Ok.. makes sense. Sure! I will make it into separate patch. Regards, Sai