From: Reinette Chatre <reinette.chatre@intel.com>
To: James Morse <james.morse@arm.com>, <x86@kernel.org>,
<linux-kernel@vger.kernel.org>
Cc: Fenghua Yu <fenghua.yu@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
H Peter Anvin <hpa@zytor.com>, Babu Moger <Babu.Moger@amd.com>,
<shameerali.kolothum.thodi@huawei.com>,
D Scott Phillips OS <scott@os.amperecomputing.com>,
<lcherian@marvell.com>, <bobo.shaobowang@huawei.com>,
<tan.shaopeng@fujitsu.com>, Jamie Iles <quic_jiles@quicinc.com>,
Cristian Marussi <cristian.marussi@arm.com>,
"Xin Hao" <xhao@linux.alibaba.com>, <xingxin.hx@openanolis.org>,
<baolin.wang@linux.alibaba.com>
Subject: Re: [PATCH v4 07/21] x86/resctrl: Create mba_sc configuration in the rdt_domain
Date: Tue, 17 May 2022 09:18:53 -0700 [thread overview]
Message-ID: <7f1c23cd-486d-9bbd-2bcc-c2db0fa1e5c2@intel.com> (raw)
In-Reply-To: <20220412124419.30689-8-james.morse@arm.com>
Hi James,
On 4/12/2022 5:44 AM, James Morse wrote:
...
> @@ -3263,6 +3295,7 @@ void resctrl_offline_domain(struct rdt_resource *r, struct rdt_domain *d)
> cancel_delayed_work(&d->cqm_limbo);
> }
>
> + mba_sc_domain_destroy(r, d);
> domain_destroy_mon_state(d);
> }
It is not clear to me how rdt_domain->mbps_val will be released via the above call.
After patch 3/21 and the hunk below resctrl_online_domain() would look like:
resctrl_online_domain() {
int err;
lockdep_assert_held(&rdtgroup_mutex);
if (is_mbm_enabled() && r->rid == RDT_RESOURCE_MBA) {
err = mba_sc_domain_allocate(r, d);
if (err)
return err;
}
if (!r->mon_capable)
return 0;
...
}
If I understand the above correctly, if MBM is enabled then all domains
of resource RDT_RESOURCE_MBA will have rdt_domain->mbps_val allocated via
resctrl_online_domain().
RDT_RESOURCE_MBA is not mon_capable, so at the time its domains go
offline, the freeing of rdt_domain->mbps_val will be skipped because
after patch 5/21 resctrl_offline_domain() would look like below so
I do not see how the hunk added above will ever end up cleaning up
allocated memory:
resctrl_offline_domain() {
lockdep_assert_held(&rdtgroup_mutex);
if (!r->mon_capable) /* RDT_RESOURCE_MBA is not mon_capable */
return 0;
...
mba_sc_domain_destroy(r, d); /* Not reached for rdt_domains of RDT_RESOURCE_MBA */
domain_destroy_mon_state(d);
}
>
> @@ -3302,12 +3335,20 @@ int resctrl_online_domain(struct rdt_resource *r, struct rdt_domain *d)
>
> lockdep_assert_held(&rdtgroup_mutex);
>
> + if (is_mbm_enabled() && r->rid == RDT_RESOURCE_MBA) {
This introduces only half of the checks that are later replaced in
patch 10 "x86/resctrl: Abstract and use supports_mba_mbps()". Could the
full check be used here for that patch to be cleaner or perhaps patch 10
could be moved to be before this patch?
> + err = mba_sc_domain_allocate(r, d);
> + if (err)
> + return err;
> + }
> +
> if (!r->mon_capable)
> return 0;
>
> err = domain_setup_mon_state(r, d);
> - if (err)
> + if (err) {
> + mba_sc_domain_destroy(r, d);
> return err;
> + }
Cleaning up after the error is reasonable but this allocation would only
ever happen if the resource is RDT_RESOURCE_MBA and it is not mon_capable.
Something would thus have gone really wrong if this cleanup is necessary.
Considering that only mon_capable resources are initialized at this point,
why not just exit right after calling mba_sc_domain_allocate()?
>
> if (is_mbm_enabled()) {
> INIT_DELAYED_WORK(&d->mbm_over, mbm_handle_overflow);
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 5d283bdd6162..46ab9fb5562e 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -15,6 +15,9 @@ int proc_resctrl_show(struct seq_file *m,
>
> #endif
>
> +/* max value for struct rdt_domain's mbps_val */
> +#define MBA_MAX_MBPS U32_MAX
> +
> /**
> * enum resctrl_conf_type - The type of configuration.
> * @CDP_NONE: No prioritisation, both code and data are controlled or monitored.
> @@ -53,6 +56,9 @@ struct resctrl_staged_config {
> * @cqm_work_cpu: worker CPU for CQM h/w counters
> * @plr: pseudo-locked region (if any) associated with domain
> * @staged_config: parsed configuration to be applied
> + * @mbps_val: When mba_sc is enabled, this holds the array of user
> + * specified control values for mba_sc in MBps, indexed
> + * by closid
> */
> struct rdt_domain {
> struct list_head list;
> @@ -67,6 +73,7 @@ struct rdt_domain {
> int cqm_work_cpu;
> struct pseudo_lock_region *plr;
> struct resctrl_staged_config staged_config[CDP_NUM_TYPES];
> + u32 *mbps_val;
> };
>
> /**
Reinette
next prev parent reply other threads:[~2022-05-17 16:19 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-12 12:43 [PATCH v4 00/21] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2022-04-12 12:43 ` [PATCH v4 01/21] x86/resctrl: Kill off alloc_enabled James Morse
2022-04-12 12:44 ` [PATCH v4 02/21] x86/resctrl: Merge mon_capable and mon_enabled James Morse
2022-04-12 12:44 ` [PATCH v4 03/21] x86/resctrl: Add domain online callback for resctrl work James Morse
[not found] ` <3acfb11b-eba2-3eb0-94d1-d24a24d03d1f@linux.alibaba.com>
2022-05-03 7:59 ` Xin Hao
2022-04-12 12:44 ` [PATCH v4 04/21] x86/resctrl: Group struct rdt_hw_domain cleanup James Morse
2022-04-12 12:44 ` [PATCH v4 05/21] x86/resctrl: Add domain offline callback for resctrl work James Morse
2022-04-12 12:44 ` [PATCH v4 06/21] x86/resctrl: Remove set_mba_sc()s control array re-initialisation James Morse
2022-04-12 12:44 ` [PATCH v4 07/21] x86/resctrl: Create mba_sc configuration in the rdt_domain James Morse
2022-05-17 16:18 ` Reinette Chatre [this message]
2022-06-07 12:07 ` James Morse
2022-05-18 16:06 ` Reinette Chatre
2022-04-12 12:44 ` [PATCH v4 08/21] x86/resctrl: Switch over to the resctrl mbps_val list James Morse
2022-05-17 16:19 ` Reinette Chatre
2022-06-07 12:07 ` James Morse
2022-04-12 12:44 ` [PATCH v4 09/21] x86/resctrl: Remove architecture copy of mbps_val James Morse
2022-04-12 12:44 ` [PATCH v4 10/21] x86/resctrl: Abstract and use supports_mba_mbps() James Morse
2022-04-12 12:44 ` [PATCH v4 11/21] x86/resctrl: Allow update_mba_bw() to update controls directly James Morse
2022-04-12 12:44 ` [PATCH v4 12/21] x86/resctrl: Calculate bandwidth from the previous __mon_event_count() chunks James Morse
2022-04-12 12:44 ` [PATCH v4 13/21] x86/resctrl: Add per-rmid arch private storage for overflow and chunks James Morse
2022-05-18 16:06 ` Reinette Chatre
2022-04-12 12:44 ` [PATCH v4 14/21] x86/resctrl: Allow per-rmid arch private storage to be reset James Morse
2022-04-12 12:44 ` [PATCH v4 15/21] x86/resctrl: Abstract __rmid_read() James Morse
2022-05-17 21:23 ` Reinette Chatre
2022-06-07 12:07 ` James Morse
2022-06-07 15:51 ` Reinette Chatre
2022-06-07 20:44 ` Fenghua Yu
2022-06-07 21:25 ` Fenghua Yu
2022-04-12 12:44 ` [PATCH v4 16/21] x86/resctrl: Pass the required parameters into resctrl_arch_rmid_read() James Morse
2022-06-07 21:07 ` Fenghua Yu
2022-06-22 15:16 ` James Morse
2022-04-12 12:44 ` [PATCH v4 17/21] x86/resctrl: Move mbm_overflow_count() " James Morse
2022-04-12 12:44 ` [PATCH v4 18/21] x86/resctrl: Move get_corrected_mbm_count() " James Morse
2022-04-12 12:44 ` [PATCH v4 19/21] x86/resctrl: Rename and change the units of resctrl_cqm_threshold James Morse
2022-05-17 21:23 ` Reinette Chatre
2022-06-07 22:08 ` Fenghua Yu
2022-06-22 15:16 ` James Morse
2022-04-12 12:44 ` [PATCH v4 20/21] x86/resctrl: Add resctrl_rmid_realloc_limit to abstract x86's boot_cpu_data James Morse
2022-04-12 12:44 ` [PATCH v4 21/21] x86/resctrl: Make resctrl_arch_rmid_read() return values in bytes James Morse
2022-04-18 8:09 ` [PATCH v4 00/21] " tan.shaopeng
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