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Message-ID: <5351d9c5-5b1d-4ae5-80fc-2a3ee7af6f11@amd.com>
Date: Thu, 29 May 2025 14:54:27 -0500
From: "Moger, Babu" <babu.moger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>, corbet@....net,
tony.luck@...el.com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com
Cc: james.morse@....com, dave.martin@....com, fenghuay@...dia.com,
x86@...nel.org, hpa@...or.com, paulmck@...nel.org,
akpm@...ux-foundation.org, thuth@...hat.com, rostedt@...dmis.org,
ardb@...nel.org, gregkh@...uxfoundation.org, daniel.sneddon@...ux.intel.com,
jpoimboe@...nel.org, alexandre.chartre@...cle.com,
pawan.kumar.gupta@...ux.intel.com, thomas.lendacky@....com,
perry.yuan@....com, seanjc@...gle.com, kai.huang@...el.com,
xiaoyao.li@...el.com, kan.liang@...ux.intel.com, xin3.li@...el.com,
ebiggers@...gle.com, xin@...or.com, sohil.mehta@...el.com,
andrew.cooper3@...rix.com, mario.limonciello@....com,
linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
peternewman@...gle.com, maciej.wieczor-retman@...el.com, eranian@...gle.com,
Xiaojian.Du@....com, gautham.shenoy@....com
Subject: Re: [PATCH v13 19/27] x86/resctrl: Add event configuration directory
under info/L3_MON/
Hi Reinette,
On 5/22/25 23:43, Reinette Chatre wrote:
> Hi Babu,
>
> On 5/15/25 3:52 PM, Babu Moger wrote:
>> Create the configuration directory and files for mbm_cntr_assign mode.
>> These configurations will be used to assign MBM events in mbm_cntr_assign
>> mode, with two default configurations created upon mounting.
>
> This just jumps in with what the patch does. Requirements for proper changelog
> should be familiar by now. The changelog *always* starts with a context.
>
> Sample:
>
> "When assignable counters are supported the
> /sys/fs/resctrl/info/L3_MON/event_configs directory contains a sub-directory
> for each MBM event that can be assigned to a counter. The MBM event
> sub-directory contains a file named "event_filter" that is used to
> view and modify which memory transactions the MBM event is configured with.
>
> Create the /sys/fs/resctrl/info/L3_MON/event_configs directory on resctrl
> mount and pre-populate it with directories for the two existing MBM events:
> mbm_total_bytes and mbm_local_bytes. Create the "event_filter" file within
> each MBM event directory with the needed *show() that displays the memory
> transactions with which the MBM event is configured."
>
Looks good. Thanks. The directory name will be "event_configs". Will
change it in the code as well.
>>
>> Example:
>> $ cd /sys/fs/resctrl/
>> $ cat info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>> local_reads, remote_reads, local_non_temporal_writes,
>> remote_non_temporal_writes, local_reads_slow_memory,
>> remote_reads_slow_memory, dirty_victim_writes_all
>>
>> $ cat info/L3_MON/counter_configs/mbm_local_bytes/event_filter
>> local_reads, local_non_temporal_writes, local_reads_slow_memory
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>> v13: Updated user doc (resctrl.rst).
>> Changed the name of the function resctrl_mkdir_info_configs to
>> resctrl_mkdir_counter_configs().
>> Replaced seq_puts() with seq_putc() where applicable.
>> Removed RFTYPE_MON_CONFIG definition. Not required.
>> Changed the name of the flag RFTYPE_CONFIG to RFTYPE_ASSIGN_CONFIG.
>> Reinette suggested RFTYPE_MBM_EVENT_CONFIG but RFTYPE_ASSIGN_CONFIG
>> seemed shorter and pricise.
>> The configuration is created using evt_list.
>> Resolved conflicts caused by the recent FS/ARCH code restructure.
>> The monitor.c/rdtgroup.c files have been split between the FS and ARCH directories.
>>
>> v12: New patch to hold the MBM event configurations for mbm_cntr_assign mode.
>> ---
>> Documentation/filesystems/resctrl.rst | 30 ++++++++++
>> fs/resctrl/internal.h | 2 +
>> fs/resctrl/monitor.c | 1 +
>> fs/resctrl/rdtgroup.c | 80 +++++++++++++++++++++++++++
>> 4 files changed, 113 insertions(+)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index 5cf2d742f04c..4eb9f007ba3d 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -306,6 +306,36 @@ with the following files:
>> # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
>> 0=30;1=30
>>
>> +"counter_configs":
>> + When the "mbm_cntr_assign" mode is supported, a dedicated directory is created
>> + under the "L3_MON" directory to store configuration files.
>
> ? it does not contain files but directories for each event, no?
>
> It will help if the text is specific. For example,
> "event_configs":
> Directory that exists when mbm_cntr_evt_assign is supported. Contains sub-directory
> for each MBM event that can be assigned to a counter. Each MBM event
> sub-directory ...
Sounds good.
>
>> +
>> + These files contain the list of configurable events. There are two default
>
> So confusing ... terminology is all over the place. Which files are even talked about here?
> "configurable events" ... are these the memory transactions or MBM events?
Should be "memory trasactions"
>
>> + configurations: mbm_local_bytes and mbm_total_bytes.
>
> "two default configurations"? These are not "configurations" but "events", no?
Sure. Should be "two default events"
>
>> +
>> + Following types of events are supported:
>
> events -> memory transactions?
Sure.
>
> I am unable to parse the above.
The following are the types of memory transactions that an MBM event can
be configured with:
>
>
>> +
>> + ==== ========================= ============================================================
>> + Bits Name Description
>> + ==== ========================= ============================================================
>> + 6 dirty_victim_writes_all Dirty Victims from the QOS domain to all types of memory
>> + 5 remote_reads_slow_memory Reads to slow memory in the non-local NUMA domain
>> + 4 local_reads_slow_memory Reads to slow memory in the local NUMA domain
>> + 3 remote_non_temporal_writes Non-temporal writes to non-local NUMA domain
>> + 2 local_non_temporal_writes Non-temporal writes to local NUMA domain
>> + 1 remote_reads Reads to memory in the non-local NUMA domain
>> + 0 local_reads Reads to memory in the local NUMA domain
>> + ==== ========================= ==========================================================
>
> Why does user need to know the bit position used to represent the memory transaction?
Not required. Will remove it.
>
>> +
>> + For example::
>> +
>> + # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_total_bytes/event_filter
>> + local_reads, remote_reads, local_non_temporal_writes, remote_non_temporal_writes,
>> + local_reads_slow_memory, remote_reads_slow_memory, dirty_victim_writes_all
>> +
>> + # cat /sys/fs/resctrl/info/L3_MON/counter_configs/mbm_local_bytes/event_filter
>> + local_reads, local_non_temporal_writes, local_reads_slow_memory
>> +
>> "max_threshold_occupancy":
>> Read/write file provides the largest value (in
>> bytes) at which a previously used LLC_occupancy
>> diff --git a/fs/resctrl/internal.h b/fs/resctrl/internal.h
>> index 019d00bf5adf..446cc9cc61df 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -238,6 +238,8 @@ struct mbm_evt_value {
>>
>> #define RFTYPE_DEBUG BIT(10)
>>
>> +#define RFTYPE_ASSIGN_CONFIG BIT(11)
>> +
>> #define RFTYPE_CTRL_INFO (RFTYPE_INFO | RFTYPE_CTRL)
>>
>> #define RFTYPE_MON_INFO (RFTYPE_INFO | RFTYPE_MON)
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 72f3dfb5b903..1f72249a5c93 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -932,6 +932,7 @@ int resctrl_mon_resource_init(void)
>> RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
>> resctrl_file_fflags_init("available_mbm_cntrs",
>> RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
>> + resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG);
>> }
>>
>> return 0;
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index b109e91096b0..cf84e3a382ac 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1911,6 +1911,25 @@ static int resctrl_available_mbm_cntrs_show(struct kernfs_open_file *of,
>> return ret;
>> }
>>
>> +static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq, void *v)
>> +{
>> + struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
>> + bool sep = false;
>> + int i;
>> +
>> + for (i = 0; i < NUM_MBM_EVT_VALUES; i++) {
>> + if (mevt->evt_cfg & mbm_evt_values[i].evt_val) {
>
> Still no idea where mevt->evt_cfg comes from. Patch ordering issue?
Yes.
Need to introduce evt_cfg member and also need to initialize the default
values during the init. Will order it correctly to make little bit clear.
>
>> + if (sep)
>> + seq_putc(seq, ',');
>> + seq_printf(seq, "%s", mbm_evt_values[i].evt_name);
>> + sep = true;
>> + }
>> + }
>> + seq_putc(seq, '\n');
>> +
>> + return 0;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>> @@ -2035,6 +2054,12 @@ static struct rftype res_common_files[] = {
>> .seq_show = mbm_local_bytes_config_show,
>> .write = mbm_local_bytes_config_write,
>> },
>> + {
>> + .name = "event_filter",
>> + .mode = 0444,
>> + .kf_ops = &rdtgroup_kf_single_ops,
>> + .seq_show = event_filter_show,
>> + },
>> {
>> .name = "mbm_assign_mode",
>> .mode = 0444,
>> @@ -2317,6 +2342,55 @@ static int rdtgroup_mkdir_info_resdir(void *priv, char *name,
>> return ret;
>> }
>>
>> +static int resctrl_mkdir_counter_configs(struct rdt_resource *r, char *name)
>> +{
>> + struct kernfs_node *l3_mon_kn, *kn_subdir, *kn_subdir2;
>> + struct mon_evt *mevt;
>> + int ret;
>> +
>> + l3_mon_kn = kernfs_find_and_get(kn_info, name);
>> + if (!l3_mon_kn)
>> + return -ENOENT;
>> +
>> + kn_subdir = kernfs_create_dir(l3_mon_kn, "counter_configs", l3_mon_kn->mode, NULL);
>> + if (IS_ERR(kn_subdir)) {
>> + kernfs_put(l3_mon_kn);
>> + return PTR_ERR(kn_subdir);
>> + }
>> +
>> + ret = rdtgroup_kn_set_ugid(kn_subdir);
>> + if (ret) {
>> + kernfs_put(l3_mon_kn);
>> + return ret;
>> + }
>> +
>> + list_for_each_entry(mevt, &r->mon.evt_list, list) {
>> + if (mevt->mbm_mode == MBM_MODE_ASSIGN) {
>
> I do not think this "mbm_mode" is needed, resctrl_mon::mbm_cntr_assignable is already used
> earlier, so would for_each_mbm_event() from the telemetry work be useful here?
Yes. Will remove mbm_mode and use Tony's telemetry work.
>
>> + kn_subdir2 = kernfs_create_dir(kn_subdir, mevt->name,
>> + kn_subdir->mode, mevt);
>> + if (IS_ERR(kn_subdir2)) {
>> + ret = PTR_ERR(kn_subdir2);
>> + goto config_out;
>
> "grep goto fs/resctrl/rdtgroup.c" for naming conventions.
Yes. I see it. It should be "out_config".
>
>> + }
>> +
>> + ret = rdtgroup_kn_set_ugid(kn_subdir2);
>> + if (ret)
>> + goto config_out;
>> +
>> + ret = rdtgroup_add_files(kn_subdir2, RFTYPE_ASSIGN_CONFIG);
>> + if (!ret)
>> + kernfs_activate(kn_subdir);
>> + }
>> + }
>> +
>> +config_out:
>> + kernfs_put(l3_mon_kn);
>> + if (ret)
>> + kernfs_remove(kn_subdir);
>
> This looks unnecessary since caller does kernfs_remove() on error return. Compare
> with how rdtgroup_mkdir_info_resdir() handles errors.
Yes. Will remove it.
>
>> +
>> + return ret;
>> +}
>> +
>> static unsigned long fflags_from_resource(struct rdt_resource *r)
>> {
>> switch (r->rid) {
>> @@ -2363,6 +2437,12 @@ static int rdtgroup_create_info_dir(struct kernfs_node *parent_kn)
>> ret = rdtgroup_mkdir_info_resdir(r, name, fflags);
>> if (ret)
>> goto out_destroy;
>> +
>> + if (r->mon.mbm_cntr_assignable) {
>> + ret = resctrl_mkdir_counter_configs(r, name);
>> + if (ret)
>> + goto out_destroy;
>> + }
>> }
>>
>> ret = rdtgroup_kn_set_ugid(kn_info);
>
> Reinette
>
--
Thanks
Babu Moger
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