kernel/linux.git/fs/resctrl/internal.h, branch v6.19.11

fs/resctrl: Update bit_usage to reflect io_alloc

2025-11-22T13:30:34+00:00

The "shareable_bits" and "bit_usage" resctrl files associated with cache resources give insight into how instances of a cache is used. Update the annotated capacity bitmasks displayed by "bit_usage" to include the cache portions allocated for I/O via the "io_alloc" feature. "shareable_bits" is a global bitmask of shareable cache with I/O and can thus not present the per-domain I/O allocations possible with the "io_alloc" feature. Revise the "shareable_bits" documentation to direct users to "bit_usage" for accurate cache usage information. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/e02a0d424129fd7f3e45822a559b1c614ae4652a.1762995456.git.babu.moger@amd.com

fs/resctrl: Introduce interface to modify io_alloc capacity bitmasks

2025-11-22T13:28:31+00:00

The io_alloc feature in resctrl enables system software to configure the portion of the cache allocated for I/O traffic. When supported, the io_alloc_cbm file in resctrl provides access to capacity bitmasks (CBMs) allocated for I/O devices. Enable users to modify io_alloc CBMs by writing to the io_alloc_cbm resctrl file when the io_alloc feature is enabled. Mirror the CBMs between CDP_CODE and CDP_DATA when CDP is enabled to present consistent I/O allocation information to user space. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/67609641b03ccfba18a8ee0bf9dbd1f3dcbecda3.1762995456.git.babu.moger@amd.com

fs/resctrl: Introduce interface to display io_alloc CBMs

2025-11-22T10:37:21+00:00

Introduce the "io_alloc_cbm" resctrl file to display the capacity bitmasks (CBMs) that represent the portions of each cache instance allocated for I/O traffic on a cache resource that supports the "io_alloc" feature. io_alloc_cbm resides in the info directory of a cache resource, for example, /sys/fs/resctrl/info/L3/. Since the resource name is part of the path, it is not necessary to display the resource name as done in the schemata file. When CDP is enabled, io_alloc routes traffic using the highest CLOSID associated with the CDP_CODE resource and that CLOSID becomes unusable for the CDP_DATA resource. The highest CLOSID of CDP_CODE and CDP_DATA resources will be kept in sync to ensure consistent user interface. In preparation for this, access the CBMs for I/O traffic through highest CLOSID of either CDP_CODE or CDP_DATA resource. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/55a3ff66a70e7ce8239f022e62b334e9d64af604.1762995456.git.babu.moger@amd.com

fs/resctrl: Add user interface to enable/disable io_alloc feature

2025-11-21T22:01:54+00:00

AMD's SDCIAE forces all SDCI lines to be placed into the L3 cache portions identified by the highest-supported L3_MASK_n register, where n is the maximum supported CLOSID. To support this, when io_alloc resctrl feature is enabled, reserve the highest CLOSID exclusively for I/O allocation traffic making it no longer available for general CPU cache allocation. Introduce user interface to enable/disable io_alloc feature and encourage users to enable io_alloc only when running workloads that can benefit from this functionality. On enable, initialize the io_alloc CLOSID with all usable CBMs across all the domains. Since CLOSIDs are managed by resctrl fs, it is least invasive to make "io_alloc is supported by maximum supported CLOSID" part of the initial resctrl fs support for io_alloc. Take care to minimally (only in error messages) expose this use of CLOSID for io_alloc to user space so that this is not required from other architectures that may support io_alloc differently in the future. When resctrl is mounted with "-o cdp" to enable code/data prioritization, there are two L3 resources that can support I/O allocation: L3CODE and L3DATA. From resctrl fs perspective the two resources share a CLOSID and the architecture's available CLOSID are halved to support this. The architecture's underlying CLOSID used by SDCIAE when CDP is enabled is the CLOSID associated with the CDP_CODE resource, but from resctrl's perspective there is only one CLOSID for both CDP_CODE and CDP_DATA. CDP_DATA is thus not usable for general (CPU) cache allocation nor I/O allocation. Keep the CDP_CODE and CDP_DATA I/O alloc status in sync to avoid any confusion to user space. That is, enabling io_alloc on CDP_CODE does so on CDP_DATA and vice-versa, and keep the I/O allocation CBMs of CDP_CODE and CDP_DATA in sync. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/c7d3037795e653e22b02d8fc73ca80d9b075031c.1762995456.git.babu.moger@amd.com

fs/resctrl: Introduce interface to display "io_alloc" support

2025-11-21T21:49:42+00:00

Introduce the "io_alloc" resctrl file to the "info" area of a cache resource, for example /sys/fs/resctrl/info/L3/io_alloc. "io_alloc" indicates support for the "io_alloc" feature that allows direct insertion of data from I/O devices into the cache. Restrict exposing support for "io_alloc" to the L3 resource that is the only resource where this feature can be backed by AMD's L3 Smart Data Cache Injection Allocation Enforcement (SDCIAE). With that, the "io_alloc" file is only visible to user space if the L3 resource supports "io_alloc". Doing so makes the file visible for all cache resources though, for example also L2 cache (if it supports cache allocation). As a consequence, add capability for file to report expected "enabled" and "disabled", as well as "not supported". Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://patch.msgid.link/e8b116a8f424128b227734bb1d433c14af478d90.1762995456.git.babu.moger@amd.com

fs/resctrl: Introduce the interface to switch between monitor modes

2025-09-15T10:49:18+00:00

Resctrl subsystem can support two monitoring modes, "mbm_event" or "default". In mbm_event mode, monitoring event can only accumulate data while it is backed by a hardware counter. In "default" mode, resctrl assumes there is a hardware counter for each event within every CTRL_MON and MON group. Introduce mbm_assign_mode resctrl file to switch between mbm_event and default modes. Example: To list the MBM monitor modes supported: $ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode [mbm_event] default To enable the "mbm_event" counter assignment mode: $ echo "mbm_event" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode To enable the "default" monitoring mode: $ echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode Reset MBM event counters automatically as part of changing the mode. Clear both architectural and non-architectural event states to prevent overflow conditions during the next event read. Clear assignable counter configuration on all the domains. Also, enable auto assignment when switching to "mbm_event" mode. Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com

fs/resctrl: Introduce the interface to modify assignments in a group

2025-09-15T10:47:17+00:00

Enable the mbm_l3_assignments resctrl file to be used to modify counter assignments of CTRL_MON and MON groups when the "mbm_event" counter assignment mode is enabled. Process the assignment modifications in the following format: :=;= Event: A valid MBM event in the /sys/fs/resctrl/info/L3_MON/event_configs directory. Domain ID: A valid domain ID. When writing, '*' applies the changes to all domains. Assignment states: _ : Unassign a counter. e : Assign a counter exclusively. Examples: $ cd /sys/fs/resctrl $ cat /sys/fs/resctrl/mbm_L3_assignments mbm_total_bytes:0=e;1=e mbm_local_bytes:0=e;1=e To unassign the counter associated with the mbm_total_bytes event on domain 0: $ echo "mbm_total_bytes:0=_" > mbm_L3_assignments $ cat /sys/fs/resctrl/mbm_L3_assignments mbm_total_bytes:0=_;1=e mbm_local_bytes:0=e;1=e To unassign the counter associated with the mbm_total_bytes event on all the domains: $ echo "mbm_total_bytes:*=_" > mbm_L3_assignments $ cat /sys/fs/resctrl/mbm_L3_assignments mbm_total_bytes:0=_;1=_ mbm_local_bytes:0=e;1=e Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com

fs/resctrl: Introduce mbm_L3_assignments to list assignments in a group

2025-09-15T10:45:34+00:00

Introduce the mbm_L3_assignments resctrl file associated with CTRL_MON and MON resource groups to display the counter assignment states of the resource group when "mbm_event" counter assignment mode is enabled. Display the list in the following format: :=;= Event: A valid MBM event listed in /sys/fs/resctrl/info/L3_MON/event_configs directory. Domain ID: A valid domain ID. The assignment state can be one of the following: _ : No counter assigned. e : Counter assigned exclusively. Example: To list the assignment states for the default group $ cd /sys/fs/resctrl $ cat /sys/fs/resctrl/mbm_L3_assignments mbm_total_bytes:0=e;1=e mbm_local_bytes:0=e;1=e Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com

fs/resctrl: Introduce mbm_assign_on_mkdir to enable assignments on mkdir

2025-09-15T10:42:02+00:00

The "mbm_event" counter assignment mode allows users to assign a hardware counter to an RMID, event pair and monitor the bandwidth as long as it is assigned. Introduce a user-configurable option that determines if a counter will automatically be assigned to an RMID, event pair when its associated monitor group is created via mkdir. Accessible when "mbm_event" counter assignment mode is enabled. Suggested-by: Peter Newman Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com

fs/resctrl: Provide interface to update the event configurations

2025-09-15T10:40:38+00:00

When "mbm_event" counter assignment mode is enabled, users can modify the event configuration by writing to the 'event_filter' resctrl file. The event configurations for mbm_event mode are located in /sys/fs/resctrl/info/L3_MON/event_configs/. Update the assignments of all CTRL_MON and MON resource groups when the event configuration is modified. Example: $ mount -t resctrl resctrl /sys/fs/resctrl $ cd /sys/fs/resctrl/ $ cat info/L3_MON/event_configs/mbm_local_bytes/event_filter local_reads,local_non_temporal_writes,local_reads_slow_memory $ echo "local_reads,local_non_temporal_writes" > info/L3_MON/event_configs/mbm_total_bytes/event_filter $ cat info/L3_MON/event_configs/mbm_total_bytes/event_filter local_reads,local_non_temporal_writes Signed-off-by: Babu Moger Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Reinette Chatre Link: https://lore.kernel.org/cover.1757108044.git.babu.moger@amd.com