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. -Peter
