Re: [PATCH v20 08/18] x86/resctrl: Prepare for new Sub-NUMA Cluster (SNC) monitor files

Reinette Chatre
2024-06-20T21:22:10Z

Hi Tony,

On 6/10/24 11:35 AM, Tony Luck wrote:
> When SNC is enabled monitoring data is collected at the SNC node
> granularity, but must be reported at L3-cache granularity for
> backwards compatibility in addition to reporting at the node
> level.
>
> Add a "ci" field to the rdt_mon_domain structure to save the
> cache information about the enclosing L3 cache for the domain.
> This provides:
>
> 1) The cache id which is needed to compose the name of the legacy
> monitoring directory, and to determine which domains should be
> summed to provide L3-scoped data.
>
> 2) The shared_cpu_map which is needed to determine which CPUs can
> be used to read the RMID counters with the MSR interface.
>
> This is the first step to an eventual goal of monitor reporting files
> like this (for a system with two SNC nodes per L3):
>
> $ cd /sys/fs/resctrl/mon_data
> $ tree mon_L3_00
> mon_L3_00 <- 00 here is L3 cache id
> ├── llc_occupancy \ These files provide legacy support
> ├── mbm_local_bytes > for non-SNC aware monitor apps
> ├── mbm_total_bytes / that expect data at L3 cache level
> ├── mon_sub_L3_00 <- 00 here is SNC node id
> │   ├── llc_occupancy \ These files are finer grained
> │   ├── mbm_local_bytes > data from each SNC node
> │   └── mbm_total_bytes /
> └── mon_sub_L3_01
> ├── llc_occupancy \
> ├── mbm_local_bytes > As above, but for node 1.
> └── mbm_total_bytes /
>
> Signed-off-by: Tony Luck <tony.luck@intel.com>
> ---
> include/linux/resctrl.h | 2 ++
> arch/x86/kernel/cpu/resctrl/internal.h | 1 +
> arch/x86/kernel/cpu/resctrl/core.c | 7 ++++++-
> arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 1 -
> arch/x86/kernel/cpu/resctrl/rdtgroup.c | 1 -
> 5 files changed, 9 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/resctrl.h b/include/linux/resctrl.h
> index 64b6ad1b22a1..d733e1f6485d 100644
> --- a/include/linux/resctrl.h
> +++ b/include/linux/resctrl.h
> @@ -96,6 +96,7 @@ struct rdt_ctrl_domain {
> /**
> * struct rdt_mon_domain - group of CPUs sharing a resctrl monitor resource
> * @hdr: common header for different domain types
> + * @ci: cache info for this domain
> * @rmid_busy_llc: bitmap of which limbo RMIDs are above threshold
> * @mbm_total: saved state for MBM total bandwidth
> * @mbm_local: saved state for MBM local bandwidth
> @@ -106,6 +107,7 @@ struct rdt_ctrl_domain {
> */
> struct rdt_mon_domain {
> struct rdt_domain_hdr hdr;
> + struct cacheinfo *ci;
> unsigned long *rmid_busy_llc;
> struct mbm_state *mbm_total;
> struct mbm_state *mbm_local;

With struct cacheinfo used here I expected cacheinfo.h to be included in
include/linux/resctrl.h since it is now needed by resctrl fs?

Reinette