Hi Babu, On 1/22/25 12:20 PM, Babu Moger wrote: > Introduce the interface file "mbm_assign_mode" to list monitor modes > supported. > > The "mbm_cntr_assign" mode provides the option to assign a counter to > an RMID, event pair and monitor the bandwidth as long as it is assigned. > > On AMD systems "mbm_cntr_assign" is backed by the ABMC (Assignable ""mbm_cntr_assign" is backed" -> ""mbm_cntr_assign" mode is backed"? > Bandwidth Monitoring Counters) hardware feature and is enabled by default. > > The "default" mode is the existing monitoring mode that works without the > explicit counter assignment, instead relying on dynamic counter assignment > by hardware that may result in hardware not dedicating a counter resulting > in monitoring data reads returning "Unavailable". > > Provide an interface to display the monitor mode on the system. > $ cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode > [mbm_cntr_assign] > default > > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > --- > --- > Documentation/arch/x86/resctrl.rst | 26 +++++++++++++++++++++ > arch/x86/kernel/cpu/resctrl/rdtgroup.c | 31 ++++++++++++++++++++++++++ > 2 files changed, 57 insertions(+) > > diff --git a/Documentation/arch/x86/resctrl.rst b/Documentation/arch/x86/resctrl.rst > index fb90f08e564e..b5defc5bce0e 100644 > --- a/Documentation/arch/x86/resctrl.rst > +++ b/Documentation/arch/x86/resctrl.rst > @@ -257,6 +257,32 @@ with the following files: > # cat /sys/fs/resctrl/info/L3_MON/mbm_local_bytes_config > 0=0x30;1=0x30;3=0x15;4=0x15 > > +"mbm_assign_mode": > + Reports the list of monitoring modes supported. The enclosed brackets > + indicate which mode is enabled. > + :: > + > + # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_mode > + [mbm_cntr_assign] > + default > + > + "mbm_cntr_assign": > + > + In mbm_cntr_assign, monitoring event can only accumulate data while "In mbm_cntr_assign, monitoring event" -> "In mbm_cntr_assign mode, a monitoring event"? > + it is backed by a hardware counter. The user-space is able to specify > + which of the events in CTRL_MON or MON groups should have a counter > + assigned using the "mbm_assign_control" file. The number of counters > + available is described in the "num_mbm_cntrs" file. Changing the mode > + may cause all counters on a resource to reset. > + > + "default": > + > + In default mode, resctrl assumes there is a hardware counter for each > + event within every CTRL_MON and MON group. On AMD platforms, it is > + recommended to use mbm_cntr_assign mode if supported, because reading > + "mbm_total_bytes" or "mbm_local_bytes" will report 'Unavailable' if Reinette
