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Message-ID: <4fa74aeb-7078-48fa-8bcc-c83389aaf73b@amd.com>
Date: Tue, 22 Jul 2025 17:55:45 -0500
From: "Moger, Babu" <bmoger@....com>
To: Reinette Chatre <reinette.chatre@...el.com>,
Babu Moger <babu.moger@....com>, corbet@....net, tony.luck@...el.com,
james.morse@....com, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
dave.hansen@...ux.intel.com
Cc: Dave.Martin@....com, x86@...nel.org, hpa@...or.com,
akpm@...ux-foundation.org, paulmck@...nel.org, rostedt@...dmis.org,
Neeraj.Upadhyay@....com, david@...hat.com, arnd@...db.de, fvdl@...gle.com,
seanjc@...gle.com, jpoimboe@...nel.org, pawan.kumar.gupta@...ux.intel.com,
xin@...or.com, manali.shukla@....com, tao1.su@...ux.intel.com,
sohil.mehta@...el.com, kai.huang@...el.com, xiaoyao.li@...el.com,
peterz@...radead.org, xin3.li@...el.com, kan.liang@...ux.intel.com,
mario.limonciello@....com, thomas.lendacky@....com, perry.yuan@....com,
gautham.shenoy@....com, chang.seok.bae@...el.com, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org, peternewman@...gle.com, eranian@...gle.com
Subject: Re: [PATCH v15 27/34] fs/resctrl: Provide interface to update the
event configurations
Hi Reinette,
On 7/17/2025 10:55 PM, Reinette Chatre wrote:
> Hi Babu,
>
> On 7/8/25 3:17 PM, Babu Moger wrote:
>> When "mbm_event" counter assignment mode is supported, users can modify
>> the event configuration by writing to the 'event_filter' resctrl file.
>> The event configurations for mbm_event mode are located in
>> /sys/fs/resctrl/info/L3_MON/event_configs/.
>>
>> Update the assignments of all CTRL_MON and MON resource groups when the
>> event configuration is modified.
>>
>> Example:
>> $ mount -t resctrl resctrl /sys/fs/resctrl
>>
>> $ cd /sys/fs/resctrl/
>>
>> $ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter
>> local_reads,local_non_temporal_writes,local_reads_slow_memory
>>
>> $ echo "local_reads,local_non_temporal_writes" >
>> info/L3_MON/event_configs/mbm_total_bytes/event_filter
>>
>> $ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> local_reads,local_non_temporal_writes
>>
>> Signed-off-by: Babu Moger <babu.moger@....com>
>> ---
>
> ...
>
>> ---
>> Documentation/filesystems/resctrl.rst | 12 +++++
>> fs/resctrl/internal.h | 1 +
>> fs/resctrl/monitor.c | 44 ++++++++++++++++
>> fs/resctrl/rdtgroup.c | 74 ++++++++++++++++++++++++++-
>> 4 files changed, 130 insertions(+), 1 deletion(-)
>>
>> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
>> index 57fd12f0aeca..06c8c08d0341 100644
>> --- a/Documentation/filesystems/resctrl.rst
>> +++ b/Documentation/filesystems/resctrl.rst
>> @@ -342,6 +342,18 @@ with the following files:
>> # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_local_bytes/event_filter
>> local_reads,local_non_temporal_writes,local_reads_slow_memory
>>
>> + Modify the event configuration by writing to the "event_filter" file within
>> + the "event_configs" directory. The read/write "event_filter" file contains the
>> + configuration of the event that reflects which memory transactions are counted by it.
>> +
>> + For example::
>> +
>> + # echo "local_reads, local_non_temporal_writes" >
>> + /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> +
>> + # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter
>> + local_reads,local_non_temporal_writes
>> +
>> "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 b107874407b2..b42890fd937a 100644
>> --- a/fs/resctrl/internal.h
>> +++ b/fs/resctrl/internal.h
>> @@ -409,6 +409,7 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>> struct mon_evt *mevt);
>> int mbm_cntr_get(struct rdt_resource *r, struct rdt_mon_domain *d,
>> struct rdtgroup *rdtgrp, enum resctrl_event_id evtid);
>> +void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt);
>>
>> #ifdef CONFIG_RESCTRL_FS_PSEUDO_LOCK
>> int rdtgroup_locksetup_enter(struct rdtgroup *rdtgrp);
>> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
>> index 787dce934903..0722e72f6cb1 100644
>> --- a/fs/resctrl/monitor.c
>> +++ b/fs/resctrl/monitor.c
>> @@ -1173,3 +1173,47 @@ void rdtgroup_unassign_cntr_event(struct rdt_mon_domain *d, struct rdtgroup *rdt
>> rdtgroup_free_config_cntr(r, d, rdtgrp, mevt->evtid);
>> }
>> }
>> +
>> +/*
>> + * rdtgroup_update_cntr_event - Update the counter assignments for the event
>> + * in a group.
>> + * @r: Resource to which update needs to be done.
>> + * @rdtgrp: Resctrl group.
>> + * @mevt: MBM monitor event.
>
> @mevt needs update match actual parameter
Sure.
>
>> + */
>> +static void rdtgroup_update_cntr_event(struct rdt_resource *r, struct rdtgroup *rdtgrp,
>> + enum resctrl_event_id evtid)
>> +{
>> + struct rdt_mon_domain *d;
>> + int cntr_id;
>> +
>> + list_for_each_entry(d, &r->mon_domains, hdr.list) {
>> + cntr_id = mbm_cntr_get(r, d, rdtgrp, evtid);
>> + if (cntr_id >= 0)
>> + resctrl_arch_config_cntr(r, d, evtid, rdtgrp->mon.rmid,
>> + rdtgrp->closid, cntr_id, true);
>> + }
>> +}
>> +
>> +/*
>> + * resctrl_update_cntr_allrdtgrp - Update the counter assignments for the event
>> + * for all the groups.
>> + * @r: Resource to which update needs to be done.
>
> @r no longer a parameter
>
Removed it.
>> + * @mevt MBM Monitor event.
>> + */
>> +void resctrl_update_cntr_allrdtgrp(struct mon_evt *mevt)
>> +{
>> + struct rdt_resource *r = resctrl_arch_get_resource(mevt->rid);
>> + struct rdtgroup *prgrp, *crgrp;
>> +
>> + /*
>> + * Find all the groups where the event is assigned and update
>> + * the assignment
>
> "update the assignment" -> "update the configuration of existing assignments" ?
>
Sure.
>> + */
>> + list_for_each_entry(prgrp, &rdt_all_groups, rdtgroup_list) {
>> + rdtgroup_update_cntr_event(r, prgrp, mevt->evtid);
>> +
>> + list_for_each_entry(crgrp, &prgrp->mon.crdtgrp_list, mon.crdtgrp_list)
>> + rdtgroup_update_cntr_event(r, crgrp, mevt->evtid);
>> + }
>> +}
>> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
>> index bb28ef7e4600..4889e7556cc7 100644
>> --- a/fs/resctrl/rdtgroup.c
>> +++ b/fs/resctrl/rdtgroup.c
>> @@ -1916,6 +1916,77 @@ static int event_filter_show(struct kernfs_open_file *of, struct seq_file *seq,
>> return 0;
>> }
>>
>> +static int resctrl_process_configs(char *tok, u32 *val)
>
> Please move to monitor.c and give more specific name. Perhaps
> resctrl_parse_mem_transactions()? Open to ideas.
Sure.
>
>> +{
>> + u32 temp_val = 0;
>> + char *evt_str;
>> + bool found;
>> + int i;
>> +
>> +next_config:
>> + if (!tok || tok[0] == '\0') {
>> + *val = temp_val;
>> + return 0;
>> + }
>> +
>> + /* Start processing the strings for each memory transaction type */
>> + evt_str = strim(strsep(&tok, ","));
>> + found = false;
>> + for (i = 0; i < NUM_MBM_TRANSACTIONS; i++) {
>> + if (!strcmp(mbm_transactions[i].name, evt_str)) {
>> + temp_val |= mbm_transactions[i].val;
>> + found = true;
>> + break;
>> + }
>> + }
>> +
>> + if (!found) {
>> + rdt_last_cmd_printf("Invalid memory transaction type %s\n", evt_str);
>> + return -EINVAL;
>> + }
>> +
>> + goto next_config;
>> +}
>> +
>> +static ssize_t event_filter_write(struct kernfs_open_file *of, char *buf,
>> + size_t nbytes, loff_t off)
>> +{
>> + struct mon_evt *mevt = rdt_kn_parent_priv(of->kn);
>> + struct rdt_resource *r;
>> + u32 evt_cfg = 0;
>> + int ret = 0;
>> +
>> + /* Valid input requires a trailing newline */
>> + if (nbytes == 0 || buf[nbytes - 1] != '\n')
>> + return -EINVAL;
>> +
>> + buf[nbytes - 1] = '\0';
>> +
>> + cpus_read_lock();
>> + mutex_lock(&rdtgroup_mutex);
>> +
>> + rdt_last_cmd_clear();
>> +
>> + r = resctrl_arch_get_resource(mevt->rid);
>> + if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
>> + rdt_last_cmd_puts("mbm_event counter assignment mode is not enabled\n");
>> + ret = -EINVAL;
>> + goto out_unlock;
>> + }
>> +
>> + ret = resctrl_process_configs(buf, &evt_cfg);
>> + if (!ret && mevt->evt_cfg != evt_cfg) {
>> + mevt->evt_cfg = evt_cfg;
>> + resctrl_update_cntr_allrdtgrp(mevt);
>> + }
>> +
>> +out_unlock:
>> + mutex_unlock(&rdtgroup_mutex);
>> + cpus_read_unlock();
>> +
>> + return ret ?: nbytes;
>> +}
>> +
>> /* rdtgroup information files for one cache resource. */
>> static struct rftype res_common_files[] = {
>> {
>> @@ -2042,9 +2113,10 @@ static struct rftype res_common_files[] = {
>> },
>> {
>> .name = "event_filter",
>> - .mode = 0444,
>> + .mode = 0644,
>> .kf_ops = &rdtgroup_kf_single_ops,
>> .seq_show = event_filter_show,
>> + .write = event_filter_write,
>> },
>> {
>> .name = "mbm_assign_mode",
>
> Reinette
>
thanks
Babu
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