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b=btv786/DSJREplSV/Y3greQQTbHUXnbWpuaxKrrv7NN35hoU5eC8In4b9mmmkUkHVT6rZszWmOZf8+R3bYXQ41YifUrZ+dvmu/Bc3fHZ3Y8w/q4OZ5HkzdEDBygDvK2wsreP0w9aqLBDQnF8/EwQCuS5docYhSFB6az6PyXVNiU= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from MW3PR12MB4553.namprd12.prod.outlook.com (2603:10b6:303:2c::19) by SJ2PR12MB7847.namprd12.prod.outlook.com (2603:10b6:a03:4d2::12) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.8272.13; Sat, 21 Dec 2024 14:20:35 +0000 Received: from MW3PR12MB4553.namprd12.prod.outlook.com ([fe80::b0ef:2936:fec1:3a87]) by MW3PR12MB4553.namprd12.prod.outlook.com ([fe80::b0ef:2936:fec1:3a87%5]) with mapi id 15.20.8272.013; Sat, 21 Dec 2024 14:20:35 +0000 Message-ID: <156e6bb5-650d-427c-8750-28b2d03cd587@amd.com> Date: Sat, 21 Dec 2024 08:20:30 -0600 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 20/24] x86/resctrl: Introduce the interface to switch between monitor modes To: Reinette Chatre , Babu Moger , corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, tony.luck@intel.com, peternewman@google.com Cc: fenghua.yu@intel.com, x86@kernel.org, hpa@zytor.com, paulmck@kernel.org, akpm@linux-foundation.org, thuth@redhat.com, rostedt@goodmis.org, xiongwei.song@windriver.com, pawan.kumar.gupta@linux.intel.com, daniel.sneddon@linux.intel.com, jpoimboe@kernel.org, perry.yuan@amd.com, sandipan.das@amd.com, kai.huang@intel.com, xiaoyao.li@intel.com, seanjc@google.com, xin3.li@intel.com, andrew.cooper3@citrix.com, ebiggers@google.com, mario.limonciello@amd.com, james.morse@arm.com, tan.shaopeng@fujitsu.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, maciej.wieczor-retman@intel.com, eranian@google.com References: <874347c318853ccaafc7efae79093f2a394bba77.1734034524.git.babu.moger@amd.com> <270bfebe-9a6f-4606-bb0e-c798e0984d3a@intel.com> Content-Language: en-US From: "Moger, Babu" In-Reply-To: <270bfebe-9a6f-4606-bb0e-c798e0984d3a@intel.com> Content-Type: text/plain; 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Sure. > >> $ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> [mbm_cntr_assign] >> default >> >> To enable the "mbm_cntr_assign" mode: >> $ echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> >> To enable the default monitoring mode: >> $ echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> >> MBM event counters will reset when mbm_assign_mode is changed. > > I think it will help to elaborate on this. > > I understand this as two parts. As stated, the hardware counters > are reset since that is what ABMC does. In this patch > there is a mbm_cntr_reset() but that does not actually reset the counters as > the above implies. > Instead, the counters are automatically reset as part of changing the mode. > resctrl triggers reset of architectural and non-architectural > state of the events because of the hardware counter reset. > > The changelog can really do more to explain what this patch does. Ok. Will do. > >> >> Signed-off-by: Babu Moger >> --- > >> --- >> Documentation/arch/x86/resctrl.rst | 15 ++++++++ >> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 50 +++++++++++++++++++++++++- >> 2 files changed, 64 insertions(+), 1 deletion(-) >> >> diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst >> index 3ec14c314606..d3a8a34cf629 100644 >> --- a/Documentation/arch/x86/resctrl.rst >> +++ b/Documentation/arch/x86/resctrl.rst >> @@ -290,6 +290,21 @@ with the following files: >> "mbm_total_bytes" or "mbm_local_bytes" will report 'Unavailable' if >> there is no counter associated with that event. >> >> + * To enable "mbm_cntr_assign" mode: >> + :: >> + >> + # echo "mbm_cntr_assign" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> + >> + * To enable default monitoring mode: >> + :: >> + >> + # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> + >> + The MBM events (mbm_total_bytes and/or mbm_local_bytes) associated with >> + counters may reset when "mbm_assign_mode" is changed. Moving to > > After looking at the final documentation it seems more appropriate to move this to > the top of the "mbm_assign_mode" section. The top already shows how to read from the > file using cat so it seems like a good match to document write to the file in the > same area. ok. > >> + mbm_cntr_assign mode require users to assign the counters to the events. >> + Otherwise, the MBM event counters will return "Unassigned" when read. > > This portion can move to the mode it applies to. ok. > >> + >> "num_mbm_cntrs": >> The number of monitoring counters available for assignment when the >> architecture supports mbm_cntr_assign mode. >> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> index 8d00b1689a80..eea534cce3d0 100644 >> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c >> @@ -939,6 +939,53 @@ static void mbm_cntr_reset(struct rdt_resource *r) >> } >> } >> >> +static ssize_t rdtgroup_mbm_assign_mode_write(struct kernfs_open_file *of, >> + char *buf, size_t nbytes, loff_t off) > > rdtgroup_ namespace is not appropriate Will rename as resctrl_ thanks Babu