Hi Reinette, On 7/17/25 23:03, Reinette Chatre wrote: > Hi Babu, > > On 7/8/25 3:17 PM, Babu Moger wrote: >> 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" monitoring mode: > > "monitoring mode" -> "counter assignment mode"? Sure. > >> $ 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 >> >> MBM event counters are automatically reset as part of changing the mode. >> Clear both architectural and non-architectural event states to prevent >> overflow conditions during the next event read. Also clear assignable >> counter configuration on all the domains. >> >> Signed-off-by: Babu Moger <babu.moger@xxxxxxx> >> --- > > ... > >> --- >> Documentation/filesystems/resctrl.rst | 22 +++++++- >> fs/resctrl/internal.h | 2 + >> fs/resctrl/monitor.c | 27 ++++++++++ >> fs/resctrl/rdtgroup.c | 72 ++++++++++++++++++++++++++- >> 4 files changed, 121 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst >> index 2b2acb55d8b1..b8a4dbe061ea 100644 >> --- a/Documentation/filesystems/resctrl.rst >> +++ b/Documentation/filesystems/resctrl.rst >> @@ -259,7 +259,8 @@ with the following files: >> >> "mbm_assign_mode": >> The supported counter assignment modes. The enclosed brackets indicate which mode >> - is enabled. >> + is enabled. The MBM events associated with counters may reset when "mbm_assign_mode" >> + is changed. >> :: >> >> # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> @@ -279,6 +280,15 @@ with the following files: >> of counters available is described in the "num_mbm_cntrs" file. Changing the >> mode may cause all counters on the resource to reset. >> >> + Moving to mbm_event counter assignment mode requires users to assign the counters >> + to the events. Otherwise, the MBM event counters will return 'Unassigned' when read. >> + >> + The mode is beneficial for AMD platforms that support more CTRL_MON >> + and MON groups than available hardware counters. By default, this >> + feature is enabled on AMD platforms with the ABMC (Assignable Bandwidth >> + Monitoring Counters) capability, ensuring counters remain assigned even >> + when the corresponding RMID is not actively used by any processor. >> + >> "default": >> >> In default mode, resctrl assumes there is a hardware counter for each >> @@ -288,6 +298,16 @@ with the following files: >> result in misleading values or display "Unavailable" if no counter is assigned >> to the event. >> >> + * To enable "mbm_event" monitoring mode: > > "monitoring mode" -> "counter assignment mode"? > Sure. >> + :: >> + >> + # echo "mbm_event" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> + >> + * To enable "default" monitoring mode: >> + :: >> + >> + # echo "default" > /sys/fs/resctrl/info/L3_MON/mbm_assign_mode >> + >> "num_mbm_cntrs": >> The maximum number of counters (total of available and assigned counters) in >> each domain when the system supports mbm_event mode. > > Reinette > > -- Thanks Babu Moger
