Re: [PATCH v14 30/32] fs/resctrl: Hide the BMEC related files when mbm_event mode is enabled

[Moger, Babu]

Hi Reinette,

On 7/7/2025 5:35 PM, Moger, Babu wrote:
> Hi Reinette,
>
>
> On 7/3/25 11:21, Reinette Chatre wrote:
> > Hi Babu,
> >
> > On 7/2/25 12:04 PM, Moger, Babu wrote:
> > > Hi Reinette,
> > >
> > > On 7/2/25 12:21, Reinette Chatre wrote:
> > > > Hi Babu,
> > > >
> > > > On 7/2/25 9:42 AM, Moger, Babu wrote:
> > > > > On 6/25/25 18:39, Reinette Chatre wrote:
> > > > > > Hi Babu,
> > > > > >
> > > > > > On 6/13/25 2:05 PM, Babu Moger wrote:
> > > > > > > BMEC (Bandwidth Monitoring Event Configuration) and mbm_event mode do not
> > > > > > > work simultaneously.
> > > > > >
> > > > > > Could you please elaborate why they do not work simultaneously?
> > > > >
> > > > > Changed the changelog.
> > > > >
> > > > > When mbm_event counter assignment mode is enabled, events are configured
> > > > > through the "event_filter" files under
> > > > > /sys/fs/resctrl/info/L3_MON/event_configs/.
> > > > >
> > > > > The default monitoring mode and with BMEC (Bandwidth Monitoring Event
> > > > > Configuration) support, events are configured using the files
> > > > > mbm_total_bytes_config or mbm_local_bytes_config in
> > > > > /sys/fs/resctrl/info/L3_MON/.
> > > >
> > > > A reasonable question here may be why not just keep using the existing
> > > > (BMEC supporting) event configuration files for event configuration? Why
> > > > are new event configuration files needed?
> > >
> > > New interface that enables users to read and write memory transaction
> > > events using human-readable strings, simplifying configuration and
> > > improving usability.
> >
> > I find the "simplifying configuration and improving usability" a bit vague
> > for a changelog. The cover letter already claims that ABMC and BMEC are
> > incompatible and links to some email discussions. I think it will be helpful
> > to summarize here why ABMC and BMEC are considered incompatible and then use
> > that as motivation to hide BMEC. The motivation in this changelog is to
> > "avoid confusion" but the motivation is stronger than that.
>
> Changed the changelog. How does this look?
>
> "The default monitoring mode and with BMEC (Bandwidth Monitoring Event
> Configuration) support, events are configured using the files
> mbm_total_bytes_config or mbm_local_bytes_config in
> /sys/fs/resctrl/info/L3_MON/.
>
> When the mbm_event counter assignment mode is enabled, event configuration
> is handled via the event_filter files under
> /sys/fs/resctrl/info/L3_MON/event_configs/. This mode allows users to read
> and write memory transaction events using human-readable strings, making
> the interface easier to use and more intuitive. Going forward, this
> mechanism can support assigning multiple counters to RMID, event pairs and
> may be extended to allow flexible, user-defined event names.
>
> Given these changes, hide the BMEC-related files when the mbm_event
> counter assignment mode is enabled. Also, update the mon_features display
> accordingly."

Here is another update.

fs/resctrl: Hide the BMEC related files when mbm_event mode is enabled

The default monitoring mode and with BMEC (Bandwidth Monitoring Event
Configuration) support, events are configured using the files
mbm_total_bytes_config or mbm_local_bytes_config in
/sys/fs/resctrl/info/L3_MON/.

When the mbm_event counter assignment mode is enabled, event 
configuration is handled via the event_filter files under
/sys/fs/resctrl/info/L3_MON/event_configs/. This mode enables users to
configure memory transaction events using human-readable strings, 
providing a more intuitive and user-friendly interface. In the future, 
this mechanism could be extended to support assigning multiple counters 
to RMID-event pairs, as well as customizable, user-defined event names. 
Also, the presence of BMEC-related configuration files may cause 
confusion when the mbm_event counter assignment mode is enabled.

To address this, these files are now hidden when the mode is active.
Additionally, the mon_features display has been updated to reflect this
change.