Re: [PATCH v3 0/5] x86,fs/resctrl: Cleanups in preparation for multiple controls support

[Reinette Chatre]

Dear x86 maintainers,

Could you please consider this series for inclusion?

Thank you very much.

Reinette

On 11/4/26 4:13 PM, Reinette Chatre wrote:
> Changes since v2:
>   - v2: https://lore.kernel.org/lkml/cover.1791406459.git.reinette.chatre@xxxxxxxxx/
>   - Rebase on v7.4-rc1.
>   - Add tags. All patches now have at least two Reviewed-by tags.
>   - No other changes.
> 
> Changes since v1:
>   - v1: https://lore.kernel.org/lkml/cover.1788452481.git.reinette.chatre@xxxxxxxxx/
>   - Rebase on x86/cache branch of tip with HEAD at:
>       50e5282df427 ("x86,fs/resctrl: Add event group descriptions for Intel Diamond Rapids")
>   - Rework all changelogs. Most now explain why each change is safe and why it
>     is needed independent of the multiple controls work. (Ben)
>   - Make subject lines more specific and fix the prefix of the patch removing
>     the non-linear bandwidth delay mapping.
>   - Keep the informational message printed when an Intel system with non-linear
>     MBA delay values is encountered, rewording it and adding the missing
>     newline. Match the related warning to the same wording. (Chenyu)
>   - Group the memory bandwidth property assignments during Intel MBA enumeration.
>   - Clarify in kernel-doc that the MSR_IA32_L{2,3}_QOS_CFG scope property only
>     applies to cache resources.
>   - Add Reviewed-by tags from Chenyu and Ben.
> 
> Hi Everybody,
> 
> For resource allocation resctrl assumes there is only one way to allocate
> portions of a resource. That is, every resource supporting allocation has a
> single control in the schemata file that user space can use to allocate
> portions of that resource.
> 
> All architectures supported by resctrl already support, or will soon support,
> multiple controls per resource. For example, the memory bandwidth resource may
> have a "maximum bandwidth" as well as a "minimum bandwidth" control.
> 
> Adding support for multiple controls to resctrl is a major endeavour. The goals
> are described in [1] and summarized in the Linux Plumbers Conference 2025
> slides [2]. The implementation is in progress, with the most recent PoC
> available at [3].
> 
> This series contains the preparatory cleanups from the PoC that are ready to be
> merged independently of the remaining work:
> - Remove the unused support for non-linear Intel MBA delay values, including a
>   user space configuration check that can never fail.
> - Make the scope of MSR_IA32_L{2,3}_QOS_CFG a private x86 property instead of
>   a resctrl filesystem cache property.
> - Drop an unnecessary helper and an unnecessary function parameter.
> 
> The only intended functional change is a reworded informational message
> printed if an Intel system with non-linear MBA delay values is encountered.
> 
> Changes since previous postings can be found in the individual patches.
> 
> [1] https://lore.kernel.org/lkml/aPtfMFfLV1l%2FRB0L@xxxxxxxxxxxxxxx/
> [2] https://lpc.events/event/19/contributions/2093/attachments/1958/4172/resctrl%20Microconference%20LPC%202025%20Tokyo.pdf
> [3] https://lore.kernel.org/lkml/d258a32f-12d5-464d-abe9-4720fb3e44b3@xxxxxxxxx/
> 
> Reinette Chatre (5):
>   x86,fs/resctrl: Remove unused non-linear bandwidth delay mapping
>   x86,fs/resctrl: Remove unnecessary non-linear MBA configuration check
>   x86,fs/resctrl: Move MSR_IA32_L{2,3}_QOS_CFG scope property to x86
>     resource
>   fs/resctrl: Drop unnecessary is_mba_linear() helper
>   fs/resctrl: Drop unnecessary parameter from
>     resctrl_io_alloc_parse_line()
> 
>  arch/x86/kernel/cpu/resctrl/core.c     | 72 ++++++++------------------
>  arch/x86/kernel/cpu/resctrl/internal.h |  4 ++
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c |  4 +-
>  fs/resctrl/ctrlmondata.c               | 15 ++----
>  fs/resctrl/rdtgroup.c                  |  7 +--
>  include/linux/resctrl.h                |  7 ---
>  6 files changed, 33 insertions(+), 76 deletions(-)
> 
> 
> base-commit: 6628e7d4c6b25c8d18f1345e3a20d21829aae7e4