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Message-ID: <5636898e-78dc-4eb1-b226-ced62372e09a@intel.com>
Date: Thu, 22 May 2025 14:02:40 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Babu Moger <babu.moger@....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 08/27] x86/resctrl: Introduce mbm_cntr_cfg to track
assignable counters at domain
Hi Babu,
shortlog: "at domain" -> "per domain"?
On 5/15/25 3:51 PM, Babu Moger wrote:
> In mbm_cntr_assign mode hardware counters are assigned/unassigned to an
> MBM event of a monitor group. Hardware counters are assigned/unassigned
> at monitoring domain level.
>
> Manage a monitoring domain's hardware counters using a per monitoring
> domain array of struct mbm_cntr_cfg that is indexed by the hardware
> counter ID. A hardware counter's configuration contains the MBM event
> ID and points to the monitoring group that it is assigned to, with a
> NULL pointer meaning that the hardware counter is available for assignment.
>
> There is no direct way to determine which hardware counters are assigned
> to a particular monitoring group. Check every entry of every hardware
> counter configuration array in every monitoring domain to query which
> MBM events of a monitoring group is tracked by hardware. Such queries are
> acceptable because of a very small number of assignable counters (32
> to 64).
>
> Suggested-by: Peter Newman <peternewman@...gle.com>
> Signed-off-by: Babu Moger <babu.moger@....com>
> ---
> v13: Resolved conflicts caused by the recent FS/ARCH code restructure.
> The files monitor.c/rdtgroup.c have been split between FS and ARCH directories.
>
> v12: Fixed the struct mbm_cntr_cfg code documentation.
> Removed few strange charactors in changelog.
> Added the counter range for better understanding.
> Moved the struct mbm_cntr_cfg definition to resctrl/internal.h as
> suggested by James.
>
> v11: Refined the change log based on Reinette's feedback.
> Fixed few style issues.
>
> v10: Patch changed completely to handle the counters at domain level.
> https://lore.kernel.org/lkml/CALPaoCj+zWq1vkHVbXYP0znJbe6Ke3PXPWjtri5AFgD9cQDCUg@mail.gmail.com/
> Removed Reviewed-by tag.
> Did not see the need to add cntr_id in mbm_state structure. Not used in the code.
>
> v9: Added Reviewed-by tag. No other changes.
>
> v8: Minor commit message changes.
>
> v7: Added check mbm_cntr_assignable for allocating bitmap mbm_cntr_map
>
> v6: New patch to add domain level assignment.
> ---
> fs/resctrl/rdtgroup.c | 11 +++++++++++
> include/linux/resctrl.h | 16 ++++++++++++++++
> 2 files changed, 27 insertions(+)
>
> diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c
> index 51f8f8d3ccbc..e2005fc9acd9 100644
> --- a/fs/resctrl/rdtgroup.c
> +++ b/fs/resctrl/rdtgroup.c
> @@ -4085,6 +4085,7 @@ static void rdtgroup_setup_default(void)
>
> static void domain_destroy_mon_state(struct rdt_mon_domain *d)
> {
> + kfree(d->cntr_cfg);
> bitmap_free(d->rmid_busy_llc);
> kfree(d->mbm_total);
> kfree(d->mbm_local);
> @@ -4171,6 +4172,16 @@ static int domain_setup_mon_state(struct rdt_resource *r, struct rdt_mon_domain
> return -ENOMEM;
> }
> }
> + if (resctrl_is_mbm_enabled() && r->mon.mbm_cntr_assignable) {
> + tsize = sizeof(*d->cntr_cfg);
> + d->cntr_cfg = kcalloc(r->mon.num_mbm_cntrs, tsize, GFP_KERNEL);
> + if (!d->cntr_cfg) {
> + bitmap_free(d->rmid_busy_llc);
> + kfree(d->mbm_total);
> + kfree(d->mbm_local);
> + return -ENOMEM;
> + }
> + }
>
> return 0;
> }
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index bdb264875ef6..d77981d1fcb9 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -156,6 +156,20 @@ struct rdt_ctrl_domain {
> u32 *mbps_val;
> };
>
> +/**
> + * struct mbm_cntr_cfg - Assignable counter configuration
> + * @evtid: MBM event to which the counter is assigned. Only valid
> + * if @rdtgroup is not NULL.
> + * @evt_cfg: Event configuration value.
@evt_cfg is not introduced in changelog nor defined here. Please add a snippet here
on what @evt_cfg's values represent. This is important since this is exposed
as resctrl fs API to architectures so all architectures need to use same values when
interacting with resctrl.
> + * @rdtgrp: resctrl group assigned to the counter. NULL if the
> + * counter is free.
> + */
> +struct mbm_cntr_cfg {
> + enum resctrl_event_id evtid;
> + u32 evt_cfg;
> + struct rdtgroup *rdtgrp;
Please align struct member names using TABs.
> +};
> +
> /**
> * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource
> * @hdr: common header for different domain types
> @@ -167,6 +181,7 @@ struct rdt_ctrl_domain {
> * @cqm_limbo: worker to periodically read CQM h/w counters
> * @mbm_work_cpu: worker CPU for MBM h/w counters
> * @cqm_work_cpu: worker CPU for CQM h/w counters
> + * @cntr_cfg: assignable counters configuration
"array of assignable counters' configuration (indexed by counter ID)"
> */
> struct rdt_mon_domain {
> struct rdt_domain_hdr hdr;
> @@ -178,6 +193,7 @@ struct rdt_mon_domain {
> struct delayed_work cqm_limbo;
> int mbm_work_cpu;
> int cqm_work_cpu;
> + struct mbm_cntr_cfg *cntr_cfg;
> };
>
> /**
Reinette
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