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 <[email protected]>
---
Documentation/x86/resctrl.rst | 142 +++++++++++++++++++++++++++++++++-
1 file changed, 140 insertions(+), 2 deletions(-)
diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
index 71a531061e4e..2860856f4463 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 +163,83 @@ 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 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 for every RMID will report "Unavailable"
+ and subsequent reads will report the valid value.
+
+ Following are the types of events supported:
+
+ ==== ========================================================
+ Bits Description
+ ==== ========================================================
+ 6 Dirty Victims from the QOS domain to all types of memory
+ 5 Reads to slow memory in the non-local NUMA domain
+ 4 Reads to slow memory in the local NUMA domain
+ 3 Non-temporal writes to non-local NUMA domain
+ 2 Non-temporal writes to local NUMA domain
+ 1 Reads to memory in the non-local NUMA domain
+ 0 Reads to memory in the local NUMA domain
+ ==== ========================================================
+
+ By default, the mbm_total_bytes configuration is set to 0x7f to count
+ all the event types and the mbm_local_bytes configuration is set to
+ 0x15 to count all the local memory events.
+
+ Examples:
+
+ * To view the current configuration::
+ ::
+
+ # cat /sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config
+ 0=0x7f;1=0x7f;2=0x7f;3=0x7f
+
+ # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
+ 0=0x15;1=0x15;3=0x15;4=0x15
+
+ * To change the mbm_total_bytes to count only reads on domain 0,
+ the bits 0, 1, 4 and 5 needs to be set, which is 110011b in binary
+ (in hexadecimal 0x33):
+ ::
+
+ # echo "0=0x33" > /sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config
+
+ # cat /sys/fs/resctrl/info/L3_MON/mbm_total_bytes_config
+ 0=0x33;1=0x7f;2=0x7f;3=0x7f
+
+ * To change the mbm_local_bytes to count all the slow memory reads on
+ domain 0 and 1, the bits 4 and 5 needs to be set, which is 110000b
+ in binary (in hexadecimal 0x30):
+ ::
+
+ # echo "0=0x30;1=0x30" > /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
+
+ # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config
+ 0=0x30;1=0x30;3=0x15;4=0x15
"max_threshold_occupancy":
Read/write file provides the largest value (in
@@ -464,6 +543,25 @@ Memory bandwidth domain is L3 cache.
MB:<cache_id0>=bw_MBps0;<cache_id1>=bw_MBps1;...
+Slow Memory Bandwidth Allocation (SMBA)
+---------------------------------------
+AMD hardware supports Slow Memory Bandwidth Allocation (SMBA).
+CXL.memory is the only supported "slow" memory device. With the
+support of SMBA, the hardware enables bandwidth allocation on
+the slow memory devices. If there are multiple such devices in
+the system, the throttling logic groups all the slow sources
+together and applies the limit on them as a whole.
+
+The presence of SMBA (with CXL.memory) is independent of slow memory
+devices presence. If there are no such devices on the system, then
+configuring SMBA will have no impact on the performance of the system.
+
+The bandwidth domain for slow memory is L3 cache. Its schemata file
+is formatted as:
+::
+
+ SMBA:<cache_id0>=bandwidth0;<cache_id1>=bandwidth1;...
+
Reading/writing the schemata file
---------------------------------
Reading the schemata file will show the state of all resources
@@ -479,6 +577,46 @@ which you wish to change. E.g.
L3DATA:0=fffff;1=fffff;2=3c0;3=fffff
L3CODE:0=fffff;1=fffff;2=fffff;3=fffff
+Reading/writing the schemata file (on AMD systems)
+--------------------------------------------------
+Reading the schemata file will show the current bandwidth limit on all
+domains. The allocated resources are in multiples of one eighth GB/s.
+When writing to the file, you need to specify what cache id you wish to
+configure the bandwidth limit.
+
+For example, to allocate 2GB/s limit on the first cache id:
+
+::
+
+ # cat schemata
+ MB:0=2048;1=2048;2=2048;3=2048
+ L3:0=ffff;1=ffff;2=ffff;3=ffff
+
+ # echo "MB:1=16" > schemata
+ # cat schemata
+ MB:0=2048;1= 16;2=2048;3=2048
+ L3:0=ffff;1=ffff;2=ffff;3=ffff
+
+Reading/writing the schemata file (on AMD systems) with SMBA feature
+--------------------------------------------------------------------
+Reading and writing the schemata file is the same as without SMBA in
+above section.
+
+For example, to allocate 8GB/s limit on the first cache id:
+
+::
+
+ # cat schemata
+ SMBA:0=2048;1=2048;2=2048;3=2048
+ MB:0=2048;1=2048;2=2048;3=2048
+ L3:0=ffff;1=ffff;2=ffff;3=ffff
+
+ # echo "SMBA:1=64" > schemata
+ # cat schemata
+ SMBA:0=2048;1= 64;2=2048;3=2048
+ MB:0=2048;1=2048;2=2048;3=2048
+ L3:0=ffff;1=ffff;2=ffff;3=ffff
+
Cache Pseudo-Locking
====================
CAT enables a user to specify the amount of cache space that an
--
2.34.1
Hi Babu,
On 1/9/2023 8:44 AM, 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 <[email protected]>
> ---
> Documentation/x86/resctrl.rst | 142 +++++++++++++++++++++++++++++++++-
> 1 file changed, 140 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
> index 71a531061e4e..2860856f4463 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"
> +=============================================== ================================
>
I expect that you will follow Boris's guidance here and not make these flags visible in
/proc/cpuinfo. That would imply that this addition will have no entries in the second
column. Perhaps this could be made easier to parse by using empty quotes ("") in the second
column to match syntax used in the existing flags as well as the cpufeatures.h change?
If/when making this change, could you please also add a note that documents this new
guidance for other resctrl developers? Something like below but I am looking forward to
improvements:
"Historically new features were made visible by default in /proc/cpuinfo. This resulted
in the flags field becoming hard to parse by humans. Adding a new flag to /proc/cpuinfo
should be avoided if user space can obtain information about the feature from resctrl's
info directory."
The rest of the document looks good to me.
Thank you
Reinette
[AMD Official Use Only - General]
Hi Reinette,
> -----Original Message-----
> From: Reinette Chatre <[email protected]>
> Sent: Wednesday, January 11, 2023 4:07 PM
> To: Moger, Babu <[email protected]>; [email protected];
> [email protected]; [email protected]; [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; Das1, Sandipan
> <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new
> features
>
> Hi Babu,
>
> On 1/9/2023 8:44 AM, 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 <[email protected]>
> > ---
> > Documentation/x86/resctrl.rst | 142
> > +++++++++++++++++++++++++++++++++-
> > 1 file changed, 140 insertions(+), 2 deletions(-)
> >
> > diff --git a/Documentation/x86/resctrl.rst
> > b/Documentation/x86/resctrl.rst index 71a531061e4e..2860856f4463
> > 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"
> > +===============================================
> ================================
> >
>
> I expect that you will follow Boris's guidance here and not make these flags
> visible in /proc/cpuinfo. That would imply that this addition will have no entries
> in the second column. Perhaps this could be made easier to parse by using
> empty quotes ("") in the second column to match syntax used in the existing
> flags as well as the cpufeatures.h change?
Hmm.. I thought we dropped that idea for now. Did I miss understand that?
Thanks
Babu
>
> If/when making this change, could you please also add a note that documents
> this new guidance for other resctrl developers? Something like below but I am
> looking forward to
> improvements:
> "Historically new features were made visible by default in /proc/cpuinfo. This
> resulted in the flags field becoming hard to parse by humans. Adding a new
> flag to /proc/cpuinfo should be avoided if user space can obtain information
> about the feature from resctrl's info directory."
>
> The rest of the document looks good to me.
>
> Thank you
>
> Reinette
Hi Babu,
On 1/11/2023 2:39 PM, Moger, Babu wrote:
> [AMD Official Use Only - General]
>
> Hi Reinette,
>
>> -----Original Message-----
>> From: Reinette Chatre <[email protected]>
>> Sent: Wednesday, January 11, 2023 4:07 PM
>> To: Moger, Babu <[email protected]>; [email protected];
>> [email protected]; [email protected]; [email protected]
>> Cc: [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected];
>> [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected];
>> [email protected]; [email protected]; Das1, Sandipan
>> <[email protected]>; [email protected]; [email protected];
>> [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]; [email protected]; [email protected];
>> [email protected]
>> Subject: Re: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new
>> features
>>
>> Hi Babu,
>>
>> On 1/9/2023 8:44 AM, 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 <[email protected]>
>>> ---
>>> Documentation/x86/resctrl.rst | 142
>>> +++++++++++++++++++++++++++++++++-
>>> 1 file changed, 140 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/x86/resctrl.rst
>>> b/Documentation/x86/resctrl.rst index 71a531061e4e..2860856f4463
>>> 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"
>>> +===============================================
>> ================================
>>>
>>
>> I expect that you will follow Boris's guidance here and not make these flags
>> visible in /proc/cpuinfo. That would imply that this addition will have no entries
>> in the second column. Perhaps this could be made easier to parse by using
>> empty quotes ("") in the second column to match syntax used in the existing
>> flags as well as the cpufeatures.h change?
>
> Hmm.. I thought we dropped that idea for now. Did I miss understand that?
I referred to the guidance in https://lore.kernel.org/lkml/[email protected]/
Since the SMBA and BMEC features have never appeared in /proc/cpuinfo there cannot
be a user space that expects these flags in /proc/cpuinfo and thus no risk of
breaking user space. User space can get information about SMBA and BMEC
from the info directory.
Later that thread discussed removal of existing resctrl feature flags from
/proc/cpuinfo - that is what I think we shouldn't do since there are
user space consumers of those flags. I thus agree that the task described in
https://lore.kernel.org/lkml/MW3PR12MB455384130AF0BDE3AF88BCF095FE9@MW3PR12MB4553.namprd12.prod.outlook.com/
can be dropped.
I do not think this is a big change ... just add the empty quotes to the
two cpufeatures.h patches and a new snippet to the resctrl documentation.
Reinette
Hi Reinette,
On 1/11/2023 4:56 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 1/11/2023 2:39 PM, Moger, Babu wrote:
>> [AMD Official Use Only - General]
>>
>> Hi Reinette,
>>
>>> -----Original Message-----
>>> From: Reinette Chatre <[email protected]>
>>> Sent: Wednesday, January 11, 2023 4:07 PM
>>> To: Moger, Babu <[email protected]>; [email protected];
>>> [email protected]; [email protected]; [email protected]
>>> Cc: [email protected]; [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected];
>>> [email protected]; [email protected];
>>> [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected];
>>> [email protected]; [email protected];
>>> [email protected]; [email protected]; Das1, Sandipan
>>> <[email protected]>; [email protected]; [email protected];
>>> [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected];
>>> [email protected]; [email protected]; [email protected];
>>> [email protected]
>>> Subject: Re: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new
>>> features
>>>
>>> Hi Babu,
>>>
>>> On 1/9/2023 8:44 AM, 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 <[email protected]>
>>>> ---
>>>> Documentation/x86/resctrl.rst | 142
>>>> +++++++++++++++++++++++++++++++++-
>>>> 1 file changed, 140 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/Documentation/x86/resctrl.rst
>>>> b/Documentation/x86/resctrl.rst index 71a531061e4e..2860856f4463
>>>> 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"
>>>> +===============================================
>>> ================================
>>> I expect that you will follow Boris's guidance here and not make these flags
>>> visible in /proc/cpuinfo. That would imply that this addition will have no entries
>>> in the second column. Perhaps this could be made easier to parse by using
>>> empty quotes ("") in the second column to match syntax used in the existing
>>> flags as well as the cpufeatures.h change?
>> Hmm.. I thought we dropped that idea for now. Did I miss understand that?
> I referred to the guidance in https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2FY7xjxUj%2BKnOEJssZ%40zn.tnic%2F&data=05%7C01%7CBabu.Moger%40amd.com%7C900eb41c0e6049dd342208daf4270d2b%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638090745842366944%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=%2F5GVOhnxq1%2B3nJwGtlApvLfC%2FeX3X9RDaUZa9R92NiY%3D&reserved=0
> Since the SMBA and BMEC features have never appeared in /proc/cpuinfo there cannot
> be a user space that expects these flags in /proc/cpuinfo and thus no risk of
> breaking user space. User space can get information about SMBA and BMEC
> from the info directory.
ok. Got it.
>
> Later that thread discussed removal of existing resctrl feature flags from
> /proc/cpuinfo - that is what I think we shouldn't do since there are
> user space consumers of those flags. I thus agree that the task described in
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Flkml%2FMW3PR12MB455384130AF0BDE3AF88BCF095FE9%40MW3PR12MB4553.namprd12.prod.outlook.com%2F&data=05%7C01%7CBabu.Moger%40amd.com%7C900eb41c0e6049dd342208daf4270d2b%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638090745842366944%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=kE7d0cFYyJq1n4ZKKeeF%2FC%2FFDDJy0Sc%2Fd5MZ%2Bc56WQw%3D&reserved=0
> can be dropped.
Sure.
> I do not think this is a big change ... just add the empty quotes to the
> two cpufeatures.h patches and a new snippet to the resctrl documentation.
How about this? I want to get this right.. Hopefully next version can be
final.
diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
index 2860856f4463..7df5889237f4 100644
--- a/Documentation/x86/resctrl.rst
+++ b/Documentation/x86/resctrl.rst
@@ -24,10 +24,15 @@ 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"
+SMBA (Slow Memory Bandwidth Allocation) ""
+BMEC (Bandwidth Monitoring Event Configuration) ""
===============================================
================================
+Historically, new features were made visible by default in
/proc/cpuinfo. This
+resulted in the feature flags becoming hard to parse by the humans.
Adding a new
+flag to /proc/cpuinfo should be avoided if user space can obtain
information
+about the feature from resctrl's info directory.
+
To use the feature mount the file system::
# mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
thanks
Babu
[AMD Official Use Only - General]
Hi Reinette,
> -----Original Message-----
> From: Reinette Chatre <[email protected]>
> Sent: Wednesday, January 11, 2023 4:56 PM
> To: Moger, Babu <[email protected]>; [email protected];
> [email protected]; [email protected]; [email protected]
> Cc: [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; Das1, Sandipan
> <[email protected]>; [email protected]; [email protected];
> [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]; [email protected]; [email protected];
> [email protected]
> Subject: Re: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst for new
> features
>
> Hi Babu,
>
> On 1/11/2023 2:39 PM, Moger, Babu wrote:
> > [AMD Official Use Only - General]
> >
> > Hi Reinette,
> >
> >> -----Original Message-----
> >> From: Reinette Chatre <[email protected]>
> >> Sent: Wednesday, January 11, 2023 4:07 PM
> >> To: Moger, Babu <[email protected]>; [email protected];
> >> [email protected]; [email protected]; [email protected]
> >> Cc: [email protected]; [email protected];
> >> [email protected]; [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]; [email protected];
> [email protected];
> >> [email protected]; [email protected];
> >> [email protected];
> >> [email protected]; [email protected]; Das1, Sandipan
> >> <[email protected]>; [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]; [email protected];
> >> [email protected]
> >> Subject: Re: [PATCH v11 13/13] Documentation/x86: Update resctrl.rst
> >> for new features
> >>
> >> Hi Babu,
> >>
> >> On 1/9/2023 8:44 AM, 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 <[email protected]>
> >>> ---
> >>> Documentation/x86/resctrl.rst | 142
> >>> +++++++++++++++++++++++++++++++++-
> >>> 1 file changed, 140 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/Documentation/x86/resctrl.rst
> >>> b/Documentation/x86/resctrl.rst index 71a531061e4e..2860856f4463
> >>> 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"
> >>> +===============================================
> >> ================================
> >>>
> >>
> >> I expect that you will follow Boris's guidance here and not make
> >> these flags visible in /proc/cpuinfo. That would imply that this
> >> addition will have no entries in the second column. Perhaps this
> >> could be made easier to parse by using empty quotes ("") in the
> >> second column to match syntax used in the existing flags as well as the
> cpufeatures.h change?
> >
> > Hmm.. I thought we dropped that idea for now. Did I miss understand that?
>
> I referred to the guidance in
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kern
> el.org%2Flkml%2FY7xjxUj%2BKnOEJssZ%40zn.tnic%2F&data=05%7C01%7CBabu
> .Moger%40amd.com%7C900eb41c0e6049dd342208daf4270d2b%7C3dd8961fe
> 4884e608e11a82d994e183d%7C0%7C0%7C638090745842366944%7CUnknown
> %7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWw
> iLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=%2F5GVOhnxq1%2B3nJwGtlAp
> vLfC%2FeX3X9RDaUZa9R92NiY%3D&reserved=0
> Since the SMBA and BMEC features have never appeared in /proc/cpuinfo
> there cannot be a user space that expects these flags in /proc/cpuinfo and thus
> no risk of breaking user space. User space can get information about SMBA and
> BMEC from the info directory.
>
> Later that thread discussed removal of existing resctrl feature flags from
> /proc/cpuinfo - that is what I think we shouldn't do since there are user space
> consumers of those flags. I thus agree that the task described in
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kern
> el.org%2Flkml%2FMW3PR12MB455384130AF0BDE3AF88BCF095FE9%40MW3P
> R12MB4553.namprd12.prod.outlook.com%2F&data=05%7C01%7CBabu.Moger
> %40amd.com%7C900eb41c0e6049dd342208daf4270d2b%7C3dd8961fe4884e6
> 08e11a82d994e183d%7C0%7C0%7C638090745842366944%7CUnknown%7CTW
> FpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVC
> I6Mn0%3D%7C3000%7C%7C%7C&sdata=kE7d0cFYyJq1n4ZKKeeF%2FC%2FFDDJ
> y0Sc%2Fd5MZ%2Bc56WQw%3D&reserved=0
> can be dropped.
>
> I do not think this is a big change ... just add the empty quotes to the two
> cpufeatures.h patches and a new snippet to the resctrl documentation.
Previous one got garbled. Here is the correct one.
diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
index 2860856f4463..7df5889237f4 100644
--- a/Documentation/x86/resctrl.rst
+++ b/Documentation/x86/resctrl.rst
@@ -24,10 +24,15 @@ 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"
+SMBA (Slow Memory Bandwidth Allocation) ""
+BMEC (Bandwidth Monitoring Event Configuration) ""
=============================================== ================================
+Historically, new features were made visible by default in /proc/cpuinfo. This
+resulted in the feature flags becoming hard to parse by the humans. Adding a new
+flag to /proc/cpuinfo should be avoided if user space can obtain information
+about the feature from resctrl's info directory.
+
To use the feature mount the file system::
# mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
Hi Babu,
On 1/11/2023 4:47 PM, Moger, Babu wrote:
> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
> index 2860856f4463..7df5889237f4 100644
> --- a/Documentation/x86/resctrl.rst
> +++ b/Documentation/x86/resctrl.rst
> @@ -24,10 +24,15 @@ 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"
> +SMBA (Slow Memory Bandwidth Allocation) ""
> +BMEC (Bandwidth Monitoring Event Configuration) ""
> =============================================== ================================
>
> +Historically, new features were made visible by default in /proc/cpuinfo. This
> +resulted in the feature flags becoming hard to parse by the humans. Adding a new
> +flag to /proc/cpuinfo should be avoided if user space can obtain information
> +about the feature from resctrl's info directory.
> +
Could you please replace "parse by the humans" with "parse by humans"?
The rest looks good to me.
Could you please do a sanity check by building the documentation to ensure
that the usage of the empty quotes looks as expected and is not parsed out by a
tool when, for example, creating the html docs?
> To use the feature mount the file system::
>
> # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
Thank you very much
Reinette
On 1/12/23 11:30, Reinette Chatre wrote:
> Hi Babu,
>
> On 1/11/2023 4:47 PM, Moger, Babu wrote:
>
>> diff --git a/Documentation/x86/resctrl.rst b/Documentation/x86/resctrl.rst
>> index 2860856f4463..7df5889237f4 100644
>> --- a/Documentation/x86/resctrl.rst
>> +++ b/Documentation/x86/resctrl.rst
>> @@ -24,10 +24,15 @@ 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"
>> +SMBA (Slow Memory Bandwidth Allocation) ""
>> +BMEC (Bandwidth Monitoring Event Configuration) ""
>> =============================================== ================================
>>
>> +Historically, new features were made visible by default in /proc/cpuinfo. This
>> +resulted in the feature flags becoming hard to parse by the humans. Adding a new
>> +flag to /proc/cpuinfo should be avoided if user space can obtain information
>> +about the feature from resctrl's info directory.
>> +
> Could you please replace "parse by the humans" with "parse by humans"?
Sure.
>
> The rest looks good to me.
>
> Could you please do a sanity check by building the documentation to ensure
> that the usage of the empty quotes looks as expected and is not parsed out by a
> tool when, for example, creating the html docs?
Yes. Will do.
Thanks
Babu
>
>> To use the feature mount the file system::
>>
>> # mount -t resctrl resctrl [-o cdp[,cdpl2][,mba_MBps]] /sys/fs/resctrl
> Thank you very much
>
> Reinette
--
Thanks
Babu Moger