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Message-ID: <b792d729-669b-4785-bdbb-23230f2e993e@amd.com>
Date: Wed, 19 Jun 2024 11:25:50 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
fenghua.yu@...el.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com
Cc: x86@...nel.org, hpa@...or.com, paulmck@...nel.org, rdunlap@...radead.org,
tj@...nel.org, peterz@...radead.org, yanjiewtw@...il.com,
kim.phillips@....com, lukas.bulwahn@...il.com, seanjc@...gle.com,
jmattson@...gle.com, leitao@...ian.org, jpoimboe@...nel.org,
rick.p.edgecombe@...el.com, kirill.shutemov@...ux.intel.com,
jithu.joseph@...el.com, kai.huang@...el.com, kan.liang@...ux.intel.com,
daniel.sneddon@...ux.intel.com, pbonzini@...hat.com, sandipan.das@....com,
ilpo.jarvinen@...ux.intel.com, peternewman@...gle.com,
maciej.wieczor-retman@...el.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, eranian@...gle.com, james.morse@....com
Subject: Re: [PATCH v4 08/19] x86/resctrl: Introduce the interface to display
monitor mode
Hi Reinette,
On 6/13/24 20:40, Reinette Chatre wrote:
> Hi Babu,
>
> On 5/24/24 5:23 AM, Babu Moger wrote:
>> The ABMC feature provides an option to the user to assign a hardware
>> counter to an RMID and monitor the bandwidth as long as it is assigned.
>> ABMC mode is enabled by default when supported. System can be one mode
>> at a time (Legacy monitor mode or ABMC mode).
>>
>> Provide an interface to display the monitor mode on the system.
>> $cat /sys/fs/resctrl/info/L3_MON/mbm_assign
>> [abmc]
>> legacy
>
> Output is different from cover letter and what this patch implements.
My bad. Will fix it,
>
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v4: Fixed the checks for legacy and abmc mode. Default it ABMC.
>>
>> v3: New patch to display ABMC capability.
>> ---
>> Documentation/arch/x86/resctrl.rst | 10 ++++++++++
>> arch/x86/kernel/cpu/resctrl/monitor.c | 1 +
>> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 23 +++++++++++++++++++++++
>> 3 files changed, 34 insertions(+)
>>
>> diff --git a/Documentation/arch/x86/resctrl.rst
>> b/Documentation/arch/x86/resctrl.rst
>> index 7ab8172ef208..ab3cde61a124 100644
>> --- a/Documentation/arch/x86/resctrl.rst
>> +++ b/Documentation/arch/x86/resctrl.rst
>> @@ -261,6 +261,16 @@ with the following files:
>> Available when ABMC feature is supported. The number of ABMC counters
>> available for configuration.
>> +"mbm_assign":
>
> This name is not ideal but I am having trouble finding a better one ... I
> have
> seen you use "monitor mode" a couple of times (even in shortlog), so maybe
> that
> could be the start of a more generic name? "mbm_mode"?
mbm_mode sounds good. Like this.
$cat /sys/fs/resctrl/info/L3_MON/mbm_mode
[abmc]
legacy
Keeping just "legacy" vs mbm_legacy.
>
>> + Available when ABMC feature is supported. Reports the list of
>> assignable
>
> Why not always make this file available? At least it will display that
> legacy mode is supported and it gives user space an always present file to
> query to
> determine support.
Ok. Sure.
>
>> + monitoring features supported. The enclosed brackets indicate which
>> + feature is enabled.
>> + ::
>> +
>> + cat /sys/fs/resctrl/info/L3_MON/mbm_assign
>> + [abmc]
>> + mbm_legacy
>> +
>> "max_threshold_occupancy":
>> Read/write file provides the largest value (in
>> bytes) at which a previously used LLC_occupancy
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c
>> b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index e75a6146068b..b1d002e5e93d 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -1071,6 +1071,7 @@ int __init rdt_get_mon_l3_config(struct
>> rdt_resource *r)
>> if (rdt_cpu_has(X86_FEATURE_ABMC)) {
>> r->abmc_capable = true;
>> + resctrl_file_fflags_init("mbm_assign", RFTYPE_MON_INFO);
>> /*
>> * Query CPUID_Fn80000020_EBX_x05 for number of
>> * ABMC counters
>> diff --git a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> index 9148d1234ede..3071bbb7a15e 100644
>> --- a/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> +++ b/arch/x86/kernel/cpu/resctrl/rdtgroup.c
>> @@ -856,6 +856,23 @@ static int rdtgroup_num_cntrs_show(struct
>> kernfs_open_file *of,
>> return 0;
>> }
>> +static int rdtgroup_mbm_assign_show(struct kernfs_open_file *of,
>> + struct seq_file *s, void *v)
>> +{
>> + struct rdt_resource *r = of->kn->parent->priv;
>> + struct rdt_hw_resource *hw_res = resctrl_to_arch_res(r);
>
> Please use arch helper to just get abmc state instead of fs code
> digging into arch structures.
Ok. I will use "resctrl_arch_get_abmc_enabled()" to get abmc state.
>
>> +
>> + if (hw_res->abmc_enabled) {
>> + seq_puts(s, "[abmc]\n");
>> + seq_puts(s, "mbm_legacy\n");
>> + } else {
>> + seq_puts(s, "abmc\n");
>> + seq_puts(s, "[mbm_legacy]\n");
>> + }
>> +
>> + return 0;
>> +}
>> +
>> #ifdef CONFIG_PROC_CPU_RESCTRL
>> /*
>> @@ -1913,6 +1930,12 @@ static struct rftype res_common_files[] = {
>> .seq_show = mbm_local_bytes_config_show,
>> .write = mbm_local_bytes_config_write,
>> },
>> + {
>> + .name = "mbm_assign",
>> + .mode = 0444,
>> + .kf_ops = &rdtgroup_kf_single_ops,
>> + .seq_show = rdtgroup_mbm_assign_show,
>> + },
>> {
>> .name = "cpus",
>> .mode = 0644,
>
> Reinette
>
--
Thanks
Babu Moger
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