On 7/15/25 7:18 AM, Moger, Babu wrote: > Hi Peter, > > On 7/15/25 08:53, Peter Newman wrote: >> 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. >> > > Agree. Thanks for pointing it out. Not the first time: https://lore.kernel.org/lkml/7fcdb142-b188-4f8d-ab26-391e0b9cec8e@xxxxxxxxx/ Reinette
