Hi All, On 2/17/25 04:26, Peter Newman wrote: > Hi Reinette, > > On Fri, Feb 14, 2025 at 8:18 PM Reinette Chatre > <reinette.chatre@xxxxxxxxx> wrote: >> >> Hi Babu, >> >> On 2/14/25 10:31 AM, Moger, Babu wrote: >>> On 2/14/2025 12:26 AM, Reinette Chatre wrote: >>>> On 2/13/25 9:37 AM, Dave Martin wrote: >>>>> On Wed, Feb 12, 2025 at 03:33:31PM -0800, Reinette Chatre wrote: >>>>>> On 2/12/25 9:46 AM, Dave Martin wrote: >>>>>>> On Wed, Jan 22, 2025 at 02:20:08PM -0600, Babu Moger wrote: >> >> (quoting relevant parts with goal to focus discussion on new possible syntax) >> >>>>>> I see the support for MPAM events distinct from the support of assignable counters. >>>>>> Once the MPAM events are sorted, I think that they can be assigned with existing interface. >>>>>> Please help me understand if you see it differently. >>>>>> >>>>>> Doing so would need to come up with alphabetical letters for these events, >>>>>> which seems to be needed for your proposal also? If we use possible flags of: >>>>>> >>>>>> mbm_local_read_bytes a >>>>>> mbm_local_write_bytes b >>>>>> >>>>>> Then mbm_assign_control can be used as: >>>>>> # echo '//0=ab;1=b' >/sys/fs/resctrl/info/L3_MON/mbm_assign_control >>>>>> # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_read_bytes >>>>>> <value> >>>>>> # cat /sys/fs/resctrl/mon_data/mon_L3_00/mbm_local_bytes >>>>>> <sum of mbm_local_read_bytes and mbm_local_write_bytes> >>>>>> >>>>>> One issue would be when resctrl needs to support more than 26 events (no more flags available), >>>>>> assuming that upper case would be used for "shared" counters (unless this interface is defined >>>>>> differently and only few uppercase letters used for it). Would this be too low of a limit? >> >> As mentioned above, one possible issue with existing interface is that >> it is limited to 26 events (assuming only lower case letters are used). The limit >> is low enough to be of concern. > > The events which can be monitored by a single counter on ABMC and MPAM > so far are combinable, so 26 counters per group today means it limits > breaking down MBM traffic for each group 26 ways. If a user complained > that a 26-way breakdown of a group's MBM traffic was limiting their > investigation, I would question whether they know what they're looking > for. Based on the discussion so far, it felt like it is not a group level breakdown. It is kind of global level breakdown. I could be wrong here. My understanding so far, MPAM has a number of global counters. It can be assigned to any domain in the system and monitor events. They also have a way to configure the events (read, write or both). Both these feature are inline with current resctrl implementation and can be easily adapted. One thing I am not clear why MPAM implementation plans to create separate files(dynamically) in /sys/fs/resctrl/info/L3_MON/ directory to read the events. We already have files in each group to read the events. # ls -l /sys/fs/resctrl/mon_data/mon_L3_00/ total 0 -r--r--r--. 1 root root 0 Feb 17 08:16 llc_occupancy -r--r--r--. 1 root root 0 Feb 17 08:16 mbm_local_bytes -r--r--r--. 1 root root 0 Feb 17 08:16 mbm_total_bytes -- Thanks Babu Moger
