linux-kernel - [PATCH v1 0/2] x86/resctrl: implement rename to help move containers' tasks

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Date:   Tue, 15 Nov 2022 16:45:13 +0100
From:   Peter Newman <peternewman@...gle.com>
To:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        "H. Peter Anvin" <hpa@...or.com>,
        James Morse <james.morse@....com>,
        Stephane Eranian <eranian@...gle.com>,
        Gaurang Upasani <gupasani@...gle.com>,
        Babu Moger <Babu.Moger@....com>, linux-kernel@...r.kernel.org,
        Peter Newman <peternewman@...gle.com>
Subject: [PATCH v1 0/2] x86/resctrl: implement rename to help move containers' tasks

Hi Reinette, Fenghua,

This patch series implements the solution Reinette suggested in the
earlier RFD thread[1] for the problem of moving a container's tasks to a
different control group on systems that don't provide enough CLOSIDs to
give every container its own control group.

Without this, we were forced to write all of the task IDs from the
container into the tasks file of the new control group. Because a group
is free to dynamically create new tasks, we found this approach
unusable.

This change originally depended on the CLOSID update race fix[2] to
provide a race-free mechanism for notifying the CPUs where moved tasks
were residing. However, now that the current guidance for group task
movement is to broadcast IPIs to all CPUs, this patch can be applied
independently.

This patch series assumes that a MON group's CLOSID can simply be
changed to that of a new parent CTRL_MON group. This is allowed on Intel
and AMD, but not MPAM implementations. While we (Google) only foresee
needing this functionality on Intel and AMD systems, this series should
hopefully be a good starting point for supporting MPAM.

These patches are based on v6.1-rc5

[1] https://lore.kernel.org/lkml/7b09fb62-e61a-65b9-a71e-ab725f527ded@intel.com/
[2] https://lore.kernel.org/lkml/20221103141641.3055981-2-peternewman@google.com/

Thanks!
-Peter

Peter Newman (2):
  x86/resctrl: factor rdtgroup lock for multi-file ops
  x86/resctrl: Implement rename op for mon groups

 arch/x86/kernel/cpu/resctrl/rdtgroup.c | 101 +++++++++++++++++++++----
 1 file changed, 88 insertions(+), 13 deletions(-)

-- 
2.38.1.493.g58b659f92b-goog