linux-kernel - Re: [PATCH v13 0/8] Add support for Sub-NUMA cluster (SNC) systems

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Message-ID: <ZW5f4iiNaaPqndKt@agluck-desk3>
Date:   Mon, 4 Dec 2023 15:25:22 -0800
From:   Tony Luck <tony.luck@...el.com>
To:     Borislav Petkov <bp@...en8.de>, Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Peter Newman <peternewman@...gle.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org
Cc:     Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        patches@...ts.linux.dev
Subject: Re: [PATCH v13 0/8] Add support for Sub-NUMA cluster (SNC) systems

On Mon, Dec 04, 2023 at 10:53:49AM -0800, Tony Luck wrote:

Boris: I've collected "Reviewed-by:" from Reinette for all patches. Babu
sent a Tested-by for the series, and Reviewed-by for each patch just
now.

So it's ready to got into your to-be-reviewed queue.

Thanks

-Tony

> The Sub-NUMA cluster feature on some Intel processors partitions the CPUs
> that share an L3 cache into two or more sets. This plays havoc with the
> Resource Director Technology (RDT) monitoring features.  Prior to this
> patch Intel has advised that SNC and RDT are incompatible.
> 
> Some of these CPU support an MSR that can partition the RMID counters in
> the same way. This allows monitoring features to be used. With the caveat
> that users must be aware that Linux may migrate tasks more frequently
> between SNC nodes than between "regular" NUMA nodes, so reading counters
> from all SNC nodes may be needed to get a complete picture of activity
> for tasks.
> 
> Cache and memory bandwidth allocation features continue to operate at
> the scope of the L3 cache.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> 
> Changes since v12:
> 
> All:
> 	Reinette - put commit tags in right order for TIP (Tested-by before
> 	Reviewed-by)
> 
> Patch 7:
> 	Fam Zheng - Check for -1 return from get_cpu_cacheinfo_id() and
> 	increase size of bitmap tracking # of L3 instances.
> 	Reinette - Add extra sanity checks. Note that this patch has
> 	some additional tweaks beyond the e-mail discussion.
> 		1) "3" is a valid return in addition to 1, 2, 4
> 		2) Added a warning if the sanity checks fail that
> 		prints number of CPU nodes and number of L3 cache
> 		instances that were found.
> 
> Patch 8:
> 	Babu - Fix grammar with an additional comma.
> 
> 
> Tony Luck (8):
>   x86/resctrl: Prepare for new domain scope
>   x86/resctrl: Prepare to split rdt_domain structure
>   x86/resctrl: Prepare for different scope for control/monitor
>     operations
>   x86/resctrl: Split the rdt_domain and rdt_hw_domain structures
>   x86/resctrl: Add node-scope to the options for feature scope
>   x86/resctrl: Introduce snc_nodes_per_l3_cache
>   x86/resctrl: Sub NUMA Cluster detection and enable
>   x86/resctrl: Update documentation with Sub-NUMA cluster changes
> 
>  Documentation/arch/x86/resctrl.rst        |  25 +-
>  include/linux/resctrl.h                   |  85 +++--
>  arch/x86/include/asm/msr-index.h          |   1 +
>  arch/x86/kernel/cpu/resctrl/internal.h    |  66 ++--
>  arch/x86/kernel/cpu/resctrl/core.c        | 433 +++++++++++++++++-----
>  arch/x86/kernel/cpu/resctrl/ctrlmondata.c |  58 +--
>  arch/x86/kernel/cpu/resctrl/monitor.c     |  68 ++--
>  arch/x86/kernel/cpu/resctrl/pseudo_lock.c |  26 +-
>  arch/x86/kernel/cpu/resctrl/rdtgroup.c    | 149 ++++----
>  9 files changed, 629 insertions(+), 282 deletions(-)
> 
> 
> base-commit: 2cc14f52aeb78ce3f29677c2de1f06c0e91471ab
> -- 
> 2.41.0
>