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Message-ID: <ea72280d-cf15-b1e4-17d2-966de7f6394e@intel.com>
Date: Wed, 4 Jan 2023 16:30:22 -0800
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....com>, <corbet@....net>,
<tglx@...utronix.de>, <mingo@...hat.com>, <bp@...en8.de>
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Subject: Re: [PATCH v10 13/13] Documentation/x86: Update resctrl.rst for new
features
Hi Babu,
On 12/22/2022 3:31 PM, Babu Moger wrote:
> Update the documentation for the new features:
> 1. Slow Memory Bandwidth allocation (SMBA).
> With this feature, the QOS enforcement policies can be applied
> to the external slow memory connected to the host. QOS enforcement
> is accomplished by assigning a Class Of Service (COS) to a processor
> and specifying allocations or limits for that COS for each resource
> to be allocated.
>
> 2. Bandwidth Monitoring Event Configuration (BMEC).
> The bandwidth monitoring events mbm_total_bytes and mbm_local_bytes
> are set to count all the total and local reads/writes respectively.
> With the introduction of slow memory, the two counters are not
> enough to count all the different types of memory events. With the
> feature BMEC, the users have the option to configure mbm_total_bytes
> and mbm_local_bytes to count the specific type of events.
>
> Also add configuration instructions with examples.
>
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
> Documentation/x86/resctrl.rst | 141 +++++++++++++++++++++++++++++++++-
> 1 file changed, 139 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
> index 71a531061e4e..bea6cab06873 100644
> --- a/Documentation/x86/resctrl.rst
> +++ b/Documentation/x86/resctrl.rst
> @@ -17,14 +17,16 @@ AMD refers to this feature as AMD Platform Quality of Service(AMD QoS).
> This feature is enabled by the CONFIG_X86_CPU_RESCTRL and the x86 /proc/cpuinfo
> flag bits:
>
> -============================================= ================================
> +=============================================== ================================
> RDT (Resource Director Technology) Allocation "rdt_a"
> CAT (Cache Allocation Technology) "cat_l3", "cat_l2"
> CDP (Code and Data Prioritization) "cdp_l3", "cdp_l2"
> CQM (Cache QoS Monitoring) "cqm_llc", "cqm_occup_llc"
> MBM (Memory Bandwidth Monitoring) "cqm_mbm_total", "cqm_mbm_local"
> MBA (Memory Bandwidth Allocation) "mba"
> -============================================= ================================
> +SMBA (Slow Memory Bandwidth Allocation) "smba"
> +BMEC (Bandwidth Monitoring Event Configuration) "bmec"
> +=============================================== ================================
>
> To use the feature mount the file system::
>
> @@ -161,6 +163,82 @@ with the following files:
> "mon_features":
> Lists the monitoring events if
> monitoring is enabled for the resource.
> + Example::
> +
> + # cat /sys/fs/resctrl/info/L3_MON/mon_features
> + llc_occupancy
> + mbm_total_bytes
> + mbm_local_bytes
> +
> + If the system supports Bandwidth Monitoring Event
> + Configuration (BMEC), then the bandwidth events will
> + be configurable. The output will be::
> +
> + # cat /sys/fs/resctrl/info/L3_MON/mon_features
> + llc_occupancy
> + mbm_total_bytes
> + mbm_total_bytes_config
> + mbm_local_bytes
> + mbm_local_bytes_config
> +
> +"mbm_total_bytes_config", "mbm_local_bytes_config":
> + Read/write files containing the configuration for the mbm_total_bytes
> + and mbm_local_bytes events, respectively, when the Bandwidth
> + Monitoring Event Configuration (BMEC) feature is supported.
> + The event configuration settings are domain specific and affect
> + all the CPUs in the domain. When an event configuration is changed,
> + the bandwidth counters for all the RMIDs and the events will be
> + cleared for that domain. The next read for every RMID will report
I think it needs to be emphasized that configuring one event impacts
all events. How about (please feel free to change): "When either event
configuration is changed, the bandwidth counters for all RMIDs of both
events (mbm_total_bytes as well as mbm_local_bytes) are cleared for that
domain. The next read ..."
> + "Unavailable" and subsequent reads will report the valid value.
> +
Reinette
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