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Message-ID: <97a2718c-9088-4762-84cb-06299bc33d3a@amd.com>
Date: Thu, 26 Jun 2025 11:47:28 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
tony.luck@...el.com, Dave.Martin@....com, james.morse@....com,
tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com
Cc: x86@...nel.org, hpa@...or.com, akpm@...ux-foundation.org,
rostedt@...dmis.org, paulmck@...nel.org, thuth@...hat.com, ardb@...nel.org,
gregkh@...uxfoundation.org, seanjc@...gle.com, thomas.lendacky@....com,
pawan.kumar.gupta@...ux.intel.com, manali.shukla@....com,
perry.yuan@....com, kai.huang@...el.com, peterz@...radead.org,
xiaoyao.li@...el.com, kan.liang@...ux.intel.com, mario.limonciello@....com,
xin3.li@...el.com, gautham.shenoy@....com, xin@...or.com,
chang.seok.bae@...el.com, fenghuay@...dia.com, peternewman@...gle.com,
maciej.wieczor-retman@...el.com, eranian@...gle.com,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v14 16/32] x86,fs/resctrl: Introduce event configuration
field in struct mon_evt
Hi Reinette,
On 6/24/25 18:51, Reinette Chatre wrote:
> Hi Babu,
>
> On 6/13/25 2:05 PM, Babu Moger wrote:
>> When supported, mbm_assign_mode allows the user to configure events to
>> track specific types of memory transactions.
>
> Since there is also a "default" mbm_assign_mode this should be made specific
> to mbm_event.
>
Changed to
"When supported, mbm_event mode allows the user to configure events to
track specific types of memory transactions."
>>
>> Introduce the evt_cfg field in struct mon_evt to define the type of memory
>> transactions tracked by a monitoring event. Also add helper functions to
>> get and set the evt_cfg value.
>
> hmmm ... this does not sound right (more below)
>
Removed the resctrl_set_mon_evt_cfg().
Changed to
"Introduce the evt_cfg field in struct mon_evt to define the type of
memory transactions tracked by a monitoring event. Also add a helper
function to get the evt_cfg value."
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v14: This is updated patch from previous patch.
>> https://lore.kernel.org/lkml/95b7f4e9d72773e8fda327fc80b429646efc3a8a.1747349530.git.babu.moger@amd.com/
>> Removed mbm_mode as it is not required anymore.
>> Added resctrl_get_mon_evt_cfg() and resctrl_set_mon_evt_cfg().
>>
>> v13: New patch to handle different event configuration types with
>> mbm_cntr_assign mode.
>> ---
>> arch/x86/kernel/cpu/resctrl/core.c | 4 ++++
>> fs/resctrl/internal.h | 4 ++++
>> fs/resctrl/monitor.c | 10 ++++++++++
>> include/linux/resctrl.h | 3 +++
>> 4 files changed, 21 insertions(+)
>>
>> diff --git a/arch/x86/kernel/cpu/resctrl/core.c b/arch/x86/kernel/cpu/resctrl/core.c
>> index 01b210febc7d..1df171d04bea 100644
>> --- a/arch/x86/kernel/cpu/resctrl/core.c
>> +++ b/arch/x86/kernel/cpu/resctrl/core.c
>> @@ -875,10 +875,14 @@ static __init bool get_rdt_mon_resources(void)
>> }
>> if (rdt_cpu_has(X86_FEATURE_CQM_MBM_TOTAL) || rdt_cpu_has(X86_FEATURE_ABMC)) {
>> resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
>> + resctrl_set_mon_evt_cfg(QOS_L3_MBM_TOTAL_EVENT_ID, MAX_EVT_CONFIG_BITS);
>> ret = true;
>> }
>> if (rdt_cpu_has(X86_FEATURE_CQM_MBM_LOCAL) || rdt_cpu_has(X86_FEATURE_ABMC)) {
>> resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
>> + resctrl_set_mon_evt_cfg(QOS_L3_MBM_LOCAL_EVENT_ID,
>> + READS_TO_LOCAL_MEM | READS_TO_LOCAL_S_MEM |
>> + NON_TEMP_WRITE_TO_LOCAL_MEM);
>> ret = true;
>> }
>
> The architecture should have no business setting the event configuration. This should
> all be managed via resctrl fs, no? I think the resctrl_set_mon_evt_cfg() helper should
> be dropped. The above initialization can be done as part of mon_event_all[] initialization
> within resctrl.
>
Moved it to resctrl_mon_resource_init().
@@ -926,7 +931,12 @@ int resctrl_mon_resource_init(void)
if (r->mon.mbm_cntr_assignable) {
resctrl_enable_mon_event(QOS_L3_MBM_TOTAL_EVENT_ID);
+ mon_event_all[QOS_L3_MBM_TOTAL_EVENT_ID].evt_cfg =
MAX_EVT_CONFIG_BITS;
+
resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
+ mon_event_all[QOS_L3_MBM_LOCAL_EVENT_ID].evt_cfg =
READS_TO_LOCAL_MEM |
+
READS_TO_LOCAL_S_MEM |
+
NON_TEMP_WRITE_TO_LOCAL_MEM;
resctrl_file_fflags_init("num_mbm_cntrs",
RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
resctrl_file_fflags_init("available_mbm_cntrs",
>>
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index 20e2c45cea64..71059c2cda16 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -56,6 +56,9 @@ static inline struct rdt_fs_context *rdt_fc2context(struct fs_context *fc)
>> * @evtid: event id
>> * @rid: index of the resource for this event
>> * @name: name of the event
>> + * @@evt_cfg: Event configuration value that represents the
>
> Extra @ in "@@evt_cfg"
Sure.
>
>> + * memory transactions (e.g., READS_TO_LOCAL_MEM,
>> + * READS_TO_REMOTE_MEM) being tracked by @evtid.
>
> Can append "Only valid if @evtid is an MBM event."
Sure.
>
>> * @configurable: true if the event is configurable
>> * @enabled: true if the event is enabled
>> */
>> @@ -63,6 +66,7 @@ struct mon_evt {
>> enum resctrl_event_id evtid;
>> enum resctrl_res_level rid;
>> char *name;
>> + u32 evt_cfg;
>> bool configurable;
>> bool enabled;
>> };
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 2893da994f3c..3e1a8239b0d3 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -884,6 +884,16 @@ bool resctrl_is_mon_event_enabled(enum resctrl_event_id eventid)
>> mon_event_all[eventid].enabled;
>> }
>>
>> +u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id evtid)
>> +{
>> + return mon_event_all[evtid].evt_cfg;
>> +}
>> +
>> +void resctrl_set_mon_evt_cfg(enum resctrl_event_id evtid, u32 evt_cfg)
>> +{
>> + mon_event_all[evtid].evt_cfg = evt_cfg;
>> +}
>> +
>> /**
>> * resctrl_mon_resource_init() - Initialise global monitoring structures.
>> *
>> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
>> index 468a4ebabc64..a58dd40b7246 100644
>> --- a/include/linux/resctrl.h
>> +++ b/include/linux/resctrl.h
>> @@ -413,6 +413,9 @@ static inline bool resctrl_is_mbm_event(enum resctrl_event_id eventid)
>> eventid <= QOS_L3_MBM_LOCAL_EVENT_ID);
>> }
>>
>> +u32 resctrl_get_mon_evt_cfg(enum resctrl_event_id eventid);
>> +void resctrl_set_mon_evt_cfg(enum resctrl_event_id eventid, u32 evt_cfg);
>
> I think resctrl_set_mon_evt_cfg() should be dropped. Any changes to mon_evt:evt_cfg
> should be via resctrl, either via initialization (all archs should use same default)
> or when user writes to the event configuration's file.
Sure.
>
>> +
>> #define for_each_mbm_event_id(eventid) \
>> for (eventid = QOS_L3_MBM_TOTAL_EVENT_ID; \
>> eventid <= QOS_L3_MBM_LOCAL_EVENT_ID; eventid++)
>
> sidenote: This change looks to be a good foundation to bring back the BMEC optimization
> you worked on earlier where it is no longer needed to read event configuration from
> hardware.
>
Yes. Sure. Will work on it later.
--
Thanks
Babu Moger
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