Hi Babu, On Wed, Jul 9, 2025 at 12:22 AM Babu Moger <babu.moger@xxxxxxx> wrote: > > The "mbm_event" counter assignment mode allows users to assign a hardware > counter to an RMID, event pair and monitor the bandwidth as long as it is > assigned. > > Introduce a user-configurable option that determines if a counter will > automatically be assigned to an RMID, event pair when its associated > monitor group is created via mkdir. > > Suggested-by: Peter Newman <peternewman@xxxxxxxxxx> > Signed-off-by: Babu Moger <babu.moger@xxxxxxx> > --- > v15: Fixed the static checker warning in resctrl_mbm_assign_on_mkdir_write() reported in > https://lore.kernel.org/lkml/dd4a1021-b996-438e-941c-69dfcea5f22a@xxxxxxxxx/ > > v14: Added rdtgroup_mutex in resctrl_mbm_assign_on_mkdir_show(). > Updated resctrl.rst for clarity. > Fixed squashing of few previous changes. > Added more code documentation. > > v13: Added Suggested-by tag. > Resolved conflicts caused by the recent FS/ARCH code restructure. > The rdtgroup.c/monitor.c file has now been split between the FS and ARCH directories. > > v12: New patch. Added after the discussion on the list. > https://lore.kernel.org/lkml/CALPaoCh8siZKjL_3yvOYGL4cF_n_38KpUFgHVGbQ86nD+Q2_SA@xxxxxxxxxxxxxx/ > --- > Documentation/filesystems/resctrl.rst | 16 ++++++++++ > fs/resctrl/monitor.c | 2 ++ > fs/resctrl/rdtgroup.c | 43 +++++++++++++++++++++++++++ > include/linux/resctrl.h | 3 ++ > 4 files changed, 64 insertions(+) > > diff --git a/Documentation/filesystems/resctrl.rst b/Documentation/filesystems/resctrl.rst > index 06c8c08d0341..f9e9a8a66cae 100644 > --- a/Documentation/filesystems/resctrl.rst > +++ b/Documentation/filesystems/resctrl.rst > @@ -354,6 +354,22 @@ with the following files: > # cat /sys/fs/resctrl/info/L3_MON/event_configs/mbm_total_bytes/event_filter > local_reads,local_non_temporal_writes > > +"mbm_assign_on_mkdir": > + Determines if a counter will automatically be assigned to an RMID, event pair > + when its associated monitor group is created via mkdir. It is enabled by default > + on boot and users can disable by writing to the interface. > + > + "0": > + Auto assignment is disabled. > + "1": > + Auto assignment is enabled. > + > + Example:: > + > + # echo 0 > /sys/fs/resctrl/info/L3_MON/mbm_assign_on_mkdir > + # cat /sys/fs/resctrl/info/L3_MON/mbm_assign_on_mkdir > + 0 > + > "max_threshold_occupancy": > Read/write file provides the largest value (in > bytes) at which a previously used LLC_occupancy > diff --git a/fs/resctrl/monitor.c b/fs/resctrl/monitor.c > index 0722e72f6cb1..ccca2330eebd 100644 > --- a/fs/resctrl/monitor.c > +++ b/fs/resctrl/monitor.c > @@ -984,6 +984,8 @@ int resctrl_mon_resource_init(void) > resctrl_file_fflags_init("available_mbm_cntrs", > RFTYPE_MON_INFO | RFTYPE_RES_CACHE); > resctrl_file_fflags_init("event_filter", RFTYPE_ASSIGN_CONFIG); > + resctrl_file_fflags_init("mbm_assign_on_mkdir", RFTYPE_MON_INFO | > + RFTYPE_RES_CACHE); > } > > return 0; > diff --git a/fs/resctrl/rdtgroup.c b/fs/resctrl/rdtgroup.c > index 4889e7556cc7..b7289ce2b3a6 100644 > --- a/fs/resctrl/rdtgroup.c > +++ b/fs/resctrl/rdtgroup.c > @@ -1987,6 +1987,42 @@ static ssize_t event_filter_write(struct kernfs_open_file *of, char *buf, > return ret ?: nbytes; > } > > +static int resctrl_mbm_assign_on_mkdir_show(struct kernfs_open_file *of, > + struct seq_file *s, void *v) > +{ > + struct rdt_resource *r = rdt_kn_parent_priv(of->kn); > + > + mutex_lock(&rdtgroup_mutex); > + rdt_last_cmd_clear(); > + > + seq_printf(s, "%u\n", r->mon.mbm_assign_on_mkdir); > + > + mutex_unlock(&rdtgroup_mutex); > + > + return 0; > +} > + > +static ssize_t resctrl_mbm_assign_on_mkdir_write(struct kernfs_open_file *of, > + char *buf, size_t nbytes, loff_t off) > +{ > + struct rdt_resource *r = rdt_kn_parent_priv(of->kn); > + bool value; > + int ret; > + > + ret = kstrtobool(buf, &value); > + if (ret) > + return ret; > + > + mutex_lock(&rdtgroup_mutex); > + rdt_last_cmd_clear(); > + > + r->mon.mbm_assign_on_mkdir = value; > + > + mutex_unlock(&rdtgroup_mutex); > + > + return 0; I noticed that "echo 0 > mbm_assign_on_mkdir" never completes. This should return nbytes. Thanks, -Peter
