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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>,
	<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 v3 06/19] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID
Date: Fri, 31 Mar 2023 16:21:12 -0700	[thread overview]
Message-ID: <37c2371c-11e6-a2ef-059a-1a0ba08c2f67@intel.com> (raw)
In-Reply-To: <20230320172620.18254-7-james.morse@arm.com>

Hi James,

On 3/20/2023 10:26 AM, James Morse wrote:

...

> +/**
> + * resctrl_closid_is_dirty - Determine if all RMID associated with this CLOSID
> + *                           are available.
> + * @closid: The CLOSID that is being queried.
> + *
> + * MPAM's equivalent of RMID are per-CLOSID, meaning a freshly allocated CLOSID
> + * may not be able to allocate clean RMID. To avoid this the allocator will
> + * only return clean CLOSID. This is enough for now as it allows MPAM systems
> + * to use resctrl. This suffers from the problem that there may be no CLOSID
> + * where all the RMID are clean, causing the CLOSID allocation to fail.
> + * This can be improved (once MPAM support is upstream) to return the cleanest
> + * CLOSID where PMG=0 is clean. This would allow the CLOSID allocation to

Why does PMG=0 have to be the clean ID? 

I am wondering about the use cases here. When a new CLOSID needs to be allocated,
would it not be useful to instead have a utility that returns the "cleanest" CLOSID?
Instead of picking an available CLOSID and then always have to check if it is
"dirty or not", why not have a utility that picks the CLOSID with the most
available PMGs?

Reinette

  reply	other threads:[~2023-03-31 23:21 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-03-20 17:26 [PATCH v3 00/19] x86/resctrl: monitored closid+rmid together, separate arch/fs locking James Morse
2023-03-20 17:26 ` [PATCH v3 01/19] x86/resctrl: Track the closid with the rmid James Morse
2023-03-20 17:26 ` [PATCH v3 02/19] x86/resctrl: Access per-rmid structures by index James Morse
2023-03-21 10:57   ` Ilpo Järvinen
2023-03-31 23:19   ` Reinette Chatre
2023-04-24 13:06   ` Peter Newman
2023-05-25 17:32     ` James Morse
2023-03-20 17:26 ` [PATCH v3 03/19] x86/resctrl: Create helper for RMID allocation and mondata dir creation James Morse
2023-03-21 11:05   ` Ilpo Järvinen
2023-03-31 23:20   ` Reinette Chatre
2023-03-20 17:26 ` [PATCH v3 04/19] x86/resctrl: Move rmid allocation out of mkdir_rdt_prepare() James Morse
2023-03-20 17:26 ` [PATCH v3 05/19] x86/resctrl: Allow RMID allocation to be scoped by CLOSID James Morse
2023-03-21 11:29   ` Ilpo Järvinen
2023-03-20 17:26 ` [PATCH v3 06/19] x86/resctrl: Allow the allocator to check if a CLOSID can allocate clean RMID James Morse
2023-03-31 23:21   ` Reinette Chatre [this message]
2023-04-27 14:09     ` James Morse
2023-03-20 17:26 ` [PATCH v3 07/19] x86/resctrl: Move CLOSID/RMID matching and setting to use helpers James Morse
2023-03-20 17:26 ` [PATCH v3 08/19] x86/resctrl: Add cpumask_any_housekeeping() for limbo/overflow James Morse
2023-03-21 13:21   ` Ilpo Järvinen
2023-04-27 14:09     ` James Morse
2023-03-21 15:14   ` Ilpo Järvinen
2023-04-27 14:09     ` James Morse
2023-04-27 14:25       ` Ilpo Järvinen
2023-05-25 17:32         ` James Morse
2023-03-31 23:24   ` Reinette Chatre
2023-04-27 14:10     ` James Morse
2023-04-27 23:36       ` Reinette Chatre
2023-05-25 17:32         ` James Morse
2023-03-20 17:26 ` [PATCH v3 09/19] x86/resctrl: Queue mon_event_read() instead of sending an IPI James Morse
2023-03-22 14:07   ` Peter Newman
2023-03-23  9:09     ` Peter Newman
2023-04-27 14:12       ` James Morse
2023-04-27 14:11     ` James Morse
2023-03-31 23:25   ` Reinette Chatre
2023-04-27 14:12     ` James Morse
2023-03-20 17:26 ` [PATCH v3 10/19] x86/resctrl: Allow resctrl_arch_rmid_read() to sleep James Morse
2023-03-31 23:26   ` Reinette Chatre
2023-04-27 14:12     ` James Morse
2023-03-20 17:26 ` [PATCH v3 11/19] x86/resctrl: Allow arch to allocate memory needed in resctrl_arch_rmid_read() James Morse
2023-03-31 23:27   ` Reinette Chatre
2023-04-27 14:19     ` James Morse
2023-04-27 23:40       ` Reinette Chatre
2023-05-25 17:31         ` James Morse
2023-03-20 17:26 ` [PATCH v3 12/19] x86/resctrl: Make resctrl_mounted checks explicit James Morse
2023-03-31 23:28   ` Reinette Chatre
2023-04-27 14:19     ` James Morse
2023-04-27 23:37       ` Reinette Chatre
2023-05-25 17:31         ` James Morse
2023-03-20 17:26 ` [PATCH v3 13/19] x86/resctrl: Move alloc/mon static keys into helpers James Morse
2023-03-20 17:26 ` [PATCH v3 14/19] x86/resctrl: Make rdt_enable_key the arch's decision to switch James Morse
2023-03-20 17:26 ` [PATCH v3 15/19] x86/resctrl: Add helpers for system wide mon/alloc capable James Morse
2023-03-31 23:29   ` Reinette Chatre
2023-04-27 14:19     ` James Morse
2023-03-20 17:26 ` [PATCH v3 16/19] x86/resctrl: Add cpu online callback for resctrl work James Morse
2023-03-31 23:29   ` Reinette Chatre
2023-03-20 17:26 ` [PATCH v3 17/19] x86/resctrl: Allow overflow/limbo handlers to be scheduled on any-but cpu James Morse
2023-03-21 15:12   ` Ilpo Järvinen
2023-03-21 15:25     ` Ilpo Järvinen
2023-04-27 14:20       ` James Morse
2023-03-20 17:26 ` [PATCH v3 18/19] x86/resctrl: Add cpu offline callback for resctrl work James Morse
2023-03-21 15:32   ` Ilpo Järvinen
2023-04-27 14:20     ` James Morse
2023-04-27 14:51       ` Ilpo Järvinen
2023-04-05 23:48   ` Reinette Chatre
2023-04-27 14:20     ` James Morse
2023-03-20 17:26 ` [PATCH v3 19/19] x86/resctrl: Separate arch and fs resctrl locks James Morse
2023-05-23 17:14 ` [PATCH v3 00/19] x86/resctrl: monitored closid+rmid together, separate arch/fs locking Tony Luck
2023-05-25 17:31   ` James Morse
2023-05-25 21:00     ` Tony Luck
2023-05-28 20:52       ` Drew Fustini

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