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Message-ID: <a549c986-5914-4e00-81d0-994c933550c2@amd.com>
Date: Wed, 6 Aug 2025 16:19:25 -0500
From: "Moger, Babu" <babu.moger@....com>
To: corbet@....net, tony.luck@...el.com, reinette.chatre@...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 v16 13/34] fs/resctrl: Introduce interface to display
number of free MBM counters
Hi Reinette,
On 7/25/25 13:29, Babu Moger wrote:
> Introduce the "available_mbm_cntrs" resctrl file to display the number of
> counters available for assignment in each domain when "mbm_event" mode is
> enabled.
>
> Signed-off-by: Babu Moger <babu.moger@....com>
> Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>
> ---
> v16: Added Reviewed-by tag.
>
> v15: Minor changelog text update.
> Minor resctrl.rst text update and corrected the error text in
> resctrl_available_mbm_cntrs_show().
> Changed the goto label to out_unlock for consistency.
>
> v14: Minor changelog update.
> Changed subject line to fs/resctrl.
>
> v13: Resolved conflicts caused by the recent FS/ARCH code restructure.
> The files monitor.c and rdtgroup.c file has now been split between
> the FS and ARCH directories.
>
> v12: Minor change to change log.
> Updated the documentation text with an example.
> Replaced seq_puts(s, ";") with seq_putc(s, ';');
> Added missing rdt_last_cmd_clear() in resctrl_available_mbm_cntrs_show().
>
> v11: Rename rdtgroup_available_mbm_cntrs_show() to resctrl_available_mbm_cntrs_show().
> Few minor text changes.
>
> v10: Patch changed to handle the counters at domain level.
> https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
> So, display logic also changed now.
>
> v9: New patch
> ---
> Documentation/filesystems/resctrl.rst | 11 ++++++
> fs/resctrl/monitor.c | 2 ++
> fs/resctrl/rdtgroup.c | 48 +++++++++++++++++++++++++++
> 3 files changed, 61 insertions(+)
>
> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst
> index 4eb27530be6f..446736dbd97f 100644
> --- a/Documentation/filesystems/resctrl.rst
> +++ b/Documentation/filesystems/resctrl.rst
> @@ -299,6 +299,17 @@ with the following files:
> # cat /sys/fs/resctrl/info/L3_MON/num_mbm_cntrs
> 0=32;1=32
>
> +"available_mbm_cntrs":
> + The number of counters available for assignment in each domain when mbm_event
> + mode is enabled on the system.
> +
> + For example, on a system with 30 available [hardware] assignable counters
> + in each of its L3 domains:
> + ::
> +
> + # cat /sys/fs/resctrl/info/L3_MON/available_mbm_cntrs
> + 0=30;1=30
> +
> "max_threshold_occupancy":
> Read/write file provides the largest value (in
> bytes) at which a previously used LLC_occupancy
> diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c
> index 4539b08db7b9..a0b0ea45c7b4 100644
> --- a/fs/resctrl/monitor.c
> +++ b/fs/resctrl/monitor.c
> @@ -931,6 +931,8 @@ int resctrl_mon_resource_init(void)
> resctrl_enable_mon_event(QOS_L3_MBM_LOCAL_EVENT_ID);
> resctrl_file_fflags_init("num_mbm_cntrs",
> RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
> + resctrl_file_fflags_init("available_mbm_cntrs",
> + RFTYPE_MON_INFO | RFTYPE_RES_CACHE);
> }
>
> return 0;
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index a09566720d4f..15d10c346307 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -1853,6 +1853,48 @@ static int resctrl_num_mbm_cntrs_show(struct kernfs_open_file *of,
> return 0;
> }
>
> +static int resctrl_available_mbm_cntrs_show(struct kernfs_open_file *of,
> + struct seq_file *s, void *v)
> +{
> + struct rdt_resource *r = rdt_kn_parent_priv(of->kn);
> + struct rdt_mon_domain *dom;
> + bool sep = false;
> + u32 cntrs, i;
> + int ret = 0;
> +
> + cpus_read_lock();
> + mutex_lock(&rdtgroup_mutex);
> +
> + rdt_last_cmd_clear();
> +
> + if (!resctrl_arch_mbm_cntr_assign_enabled(r)) {
> + rdt_last_cmd_puts("mbm_event mode is not enabled\n");
> + ret = -EINVAL;
> + goto out_unlock;
> + }
> +
> + list_for_each_entry(dom, &r->mon_domains, hdr.list) {
> + if (sep)
> + seq_putc(s, ';');
> +
> + cntrs = 0;
> + for (i = 0; i < r->mon.num_mbm_cntrs; i++) {
> + if (!dom->cntr_cfg[i].rdtgrp)
> + cntrs++;
> + }
> +
> + seq_printf(s, "%d=%u", dom->hdr.id, cntrs);
> + sep = true;
> + }
> + seq_putc(s, '\n');
> +
> +out_unlock:
> + mutex_unlock(&rdtgroup_mutex);
> + cpus_read_unlock();
> +
> + return ret;
> +}
> +
This also can be moved to monitor.c. What do you think?
> /* rdtgroup information files for one cache resource. */
> static struct rftype res_common_files[] = {
> {
> @@ -1876,6 +1918,12 @@ static struct rftype res_common_files[] = {
> .seq_show = rdt_mon_features_show,
> .fflags = RFTYPE_MON_INFO,
> },
> + {
> + .name = "available_mbm_cntrs",
> + .mode = 0444,
> + .kf_ops = &rdtgroup_kf_single_ops,
> + .seq_show = resctrl_available_mbm_cntrs_show,
> + },
> {
> .name = "num_rmids",
> .mode = 0444,
--
Thanks
Babu Moger
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