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Message-ID: <a443cb17-3d50-4cb8-8208-e74fdd923897@intel.com>
Date: Wed, 24 Apr 2024 21:38:22 -0700
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v3 09/16] selftests/resctrl: Simplify mem bandwidth file
 code for MBA & MBM tests
To: =?UTF-8?Q?Ilpo_J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>,
	<linux-kselftest@vger.kernel.org>, Shuah Khan <shuah@kernel.org>, Babu Moger
	<babu.moger@amd.com>, =?UTF-8?Q?Maciej_Wiecz=C3=B3r-Retman?=
	<maciej.wieczor-retman@intel.com>
CC: Fenghua Yu <fenghua.yu@intel.com>, <linux-kernel@vger.kernel.org>
References: <20240408163247.3224-1-ilpo.jarvinen@linux.intel.com>
 <20240408163247.3224-10-ilpo.jarvinen@linux.intel.com>
Content-Language: en-US
From: Reinette Chatre <reinette.chatre@intel.com>
In-Reply-To: <20240408163247.3224-10-ilpo.jarvinen@linux.intel.com>
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Hi Ilpo,

On 4/8/2024 9:32 AM, Ilpo Järvinen wrote:
> initialize_mem_bw_resctrl() and set_mbm_path() contain complicated set
> of conditions, each yielding different file to be opened to measure
> memory bandwidth through resctrl FS. In practice, only two of them are
> used. For MBA test, ctrlgrp is always provided, and for MBM test both
> ctrlgrp and mongrp are set.
> 
> The file used differ between MBA/MBM test, however, MBM test
> unnecessarily create monitor group because resctrl FS already provides
> monitoring interface underneath any ctrlgrp too, which is what the MBA
> selftest uses.
> 
> Consolidate memory bandwidth file used to the one used by the MBA
> selftest. Remove all unused branches opening other files to simplify
> the code.

This is a good change but it seems incomplete to me. As changelog states
MBM creates monitor group unnecessarily, but from what I can tell it continues
to do so after this change. It is also optimized in patch 16, which I think
may end up being dropped as part of cleaning this up (here and for the CMT test).

Reinette