From: James Morse <james.morse@arm.com>
To: Reinette Chatre <reinette.chatre@intel.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>,
carl@os.amperecomputing.com, lcherian@marvell.com,
bobo.shaobowang@huawei.com, tan.shaopeng@fujitsu.com,
xingxin.hx@openanolis.org, baolin.wang@linux.alibaba.com,
Jamie Iles <quic_jiles@quicinc.com>,
Xin Hao <xhao@linux.alibaba.com>,
peternewman@google.com
Subject: Re: [PATCH v2 16/18] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu
Date: Mon, 6 Mar 2023 11:34:16 +0000 [thread overview]
Message-ID: <cdabc034-1365-d254-8ce5-b5a70d45a28e@arm.com> (raw)
In-Reply-To: <ab71c33e-f1e3-63be-ac83-685d11c8b4eb@intel.com>
Hi Reinette,
On 02/02/2023 23:49, Reinette Chatre wrote:
> On 1/13/2023 9:54 AM, James Morse wrote:
>> When a cpu is taken offline resctrl may need to move the overflow or
>> limbo handlers to run on a different CPU.
>> Once the offline callbacks have been split, cqm_setup_limbo_handler()
>> will be called while the CPU that is going offline is still present
>> in the cpu_mask.
>>
>> Pass the CPU to exclude to cqm_setup_limbo_handler() and
>> mbm_setup_overflow_handler(). These functions can use cpumask_any_but()
>> when selecting the CPU. -1 is used to indicate no CPUs need excluding.
>> diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
>> index 1a214bd32ed4..334fb3f1c6e2 100644
>> --- a/arch/x86/kernel/cpu/resctrl/monitor.c
>> +++ b/arch/x86/kernel/cpu/resctrl/monitor.c
>> @@ -773,15 +773,27 @@ void cqm_handle_limbo(struct work_struct *work)
>> mutex_unlock(&rdtgroup_mutex);
>> }
>>
>> -void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms)
>> +/**
>> + * cqm_setup_limbo_handler() - Schedule the limbo handler to run for this
>> + * domain.
>> + * @delay_ms: How far in the future the handler should run.
>> + * @exclude_cpu: Which CPU the handler should not run on, -1 to pick any CPU.
>> + */
>> +void cqm_setup_limbo_handler(struct rdt_domain *dom, unsigned long delay_ms,
>> + int exclude_cpu)
>> {
>> unsigned long delay = msecs_to_jiffies(delay_ms);
>> int cpu;
>>
>> - cpu = cpumask_any(&dom->cpu_mask);
>> + if (exclude_cpu == -1)
>> + cpu = cpumask_any(&dom->cpu_mask);
>> + else
>> + cpu = cpumask_any_but(&dom->cpu_mask, exclude_cpu);
>> +
>> dom->cqm_work_cpu = cpu;
>>
>
> This assignment is unexpected considering the error handling that follows.
> cqm_work_cpu can thus be >= nr_cpu_ids. I assume it is to help during
> domain remove where the CPU being removed is checked against this value?
> If indeed this invalid CPU assignment is done in support of future code
> path, could you please add a comment to help explain this assignment?
Looks like I ignored it because in the last-man-standing case, the domain is going to get
free()d anyway ... but I couldn't find a 'cpu >= nr_cpu_ids' check under
schedule_delayed_work_on() hence the error handling.
I'll move the dom->mbm_work_cpu under the nr_cpu_ids check too so that it doesn't look funny.
Thanks,
James
next prev parent reply other threads:[~2023-03-06 11:34 UTC|newest]
Thread overview: 73+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-13 17:54 [PATCH v2 00/18] x86/resctrl: monitored closid+rmid together, separate arch/fs locking James Morse
2023-01-13 17:54 ` [PATCH v2 01/18] x86/resctrl: Track the closid with the rmid James Morse
2023-01-13 17:54 ` [PATCH v2 02/18] x86/resctrl: Access per-rmid structures by index James Morse
2023-01-17 18:28 ` Yu, Fenghua
2023-03-03 18:33 ` James Morse
2023-01-17 18:29 ` Yu, Fenghua
2023-02-02 23:44 ` Reinette Chatre
2023-03-03 18:33 ` James Morse
2023-01-13 17:54 ` [PATCH v2 03/18] x86/resctrl: Create helper for RMID allocation and mondata dir creation James Morse
2023-01-13 17:54 ` [PATCH v2 04/18] x86/resctrl: Move rmid allocation out of mkdir_rdt_prepare() James Morse
2023-01-17 18:28 ` Yu, Fenghua
2023-02-02 23:45 ` Reinette Chatre
2023-03-03 18:33 ` James Morse
2023-01-13 17:54 ` [PATCH v2 05/18] x86/resctrl: Allow RMID allocation to be scoped by CLOSID James Morse
2023-01-17 18:53 ` Yu, Fenghua
2023-03-03 18:34 ` James Morse
2023-02-02 23:45 ` Reinette Chatre
2023-03-03 18:34 ` James Morse
2023-03-10 19:57 ` Reinette Chatre
2023-01-13 17:54 ` [PATCH v2 06/18] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID James Morse
2023-01-17 18:29 ` Yu, Fenghua
2023-03-03 18:35 ` James Morse
2023-02-02 23:46 ` Reinette Chatre
2023-03-03 18:36 ` James Morse
2023-03-10 19:59 ` Reinette Chatre
2023-03-20 17:12 ` James Morse
2023-01-13 17:54 ` [PATCH v2 07/18] x86/resctrl: Move CLOSID/RMID matching and setting to use helpers James Morse
2023-01-17 19:10 ` Yu, Fenghua
2023-03-03 18:37 ` James Morse
2023-02-02 23:47 ` Reinette Chatre
2023-03-06 11:32 ` James Morse
2023-03-08 10:30 ` Peter Newman
2023-03-10 20:00 ` Reinette Chatre
2023-01-13 17:54 ` [PATCH v2 08/18] x86/resctrl: Queue mon_event_read() instead of sending an IPI James Morse
2023-01-17 18:29 ` Yu, Fenghua
2023-03-06 11:32 ` James Morse
2023-03-10 20:00 ` Reinette Chatre
2023-02-02 23:47 ` Reinette Chatre
2023-03-06 11:33 ` James Morse
2023-03-08 16:09 ` James Morse
2023-03-10 20:06 ` Reinette Chatre
2023-03-20 17:12 ` James Morse
2023-01-13 17:54 ` [PATCH v2 09/18] x86/resctrl: Allow resctrl_arch_rmid_read() to sleep James Morse
2023-01-23 13:54 ` Peter Newman
2023-03-06 11:33 ` James Morse
2023-01-23 15:33 ` Peter Newman
2023-03-06 11:33 ` James Morse
2023-03-06 13:14 ` Peter Newman
2023-03-08 17:45 ` James Morse
2023-03-09 13:41 ` Peter Newman
2023-03-09 17:35 ` James Morse
2023-03-10 9:28 ` Peter Newman
2023-03-20 17:12 ` James Morse
2023-03-22 13:21 ` Peter Newman
2023-01-13 17:54 ` [PATCH v2 10/18] x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read() James Morse
2023-01-13 17:54 ` [PATCH v2 11/18] x86/resctrl: Make resctrl_mounted checks explicit James Morse
2023-01-13 17:54 ` [PATCH v2 12/18] x86/resctrl: Move alloc/mon static keys into helpers James Morse
2023-01-13 17:54 ` [PATCH v2 13/18] x86/resctrl: Make rdt_enable_key the arch's decision to switch James Morse
2023-02-02 23:48 ` Reinette Chatre
2023-01-13 17:54 ` [PATCH v2 14/18] x86/resctrl: Add helpers for system wide mon/alloc capable James Morse
2023-01-25 7:16 ` Shaopeng Tan (Fujitsu)
2023-03-06 11:34 ` James Morse
2023-01-13 17:54 ` [PATCH v2 15/18] x86/resctrl: Add cpu online callback for resctrl work James Morse
2023-01-13 17:54 ` [PATCH v2 16/18] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu James Morse
2023-02-02 23:49 ` Reinette Chatre
2023-03-06 11:34 ` James Morse [this message]
2023-01-13 17:54 ` [PATCH v2 17/18] x86/resctrl: Add cpu offline callback for resctrl work James Morse
2023-01-13 17:54 ` [PATCH v2 18/18] x86/resctrl: Separate arch and fs resctrl locks James Morse
2023-02-02 23:50 ` Reinette Chatre
2023-03-06 11:34 ` James Morse
2023-03-11 0:22 ` Reinette Chatre
2023-03-20 17:12 ` James Morse
2023-01-25 7:19 ` [PATCH v2 00/18] x86/resctrl: monitored closid+rmid together, separate arch/fs locking Shaopeng Tan (Fujitsu)
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