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Message-ID: <e3a6e460-b7d8-4164-ad0d-894e78c323d1@intel.com>
Date: Thu, 17 Jul 2025 20:55:21 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: 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 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
> + */
> +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
> + * @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" ?
> + */
> + 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.
> +{
> + 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
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