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author | Peter Newman <peternewman@google.com> | 2022-12-20 17:41:32 +0100 |
---|---|---|
committer | Dave Hansen <dave.hansen@linux.intel.com> | 2023-03-15 15:44:15 -0700 |
commit | 322b72e0fd10101f2da8985b31b4af70f184bf79 (patch) | |
tree | 5ae8dcbf8f5e5d96b951eb7d207a0f4f256c3123 /arch/x86/kernel/cpu | |
parent | eeac8ede17557680855031c6f305ece2378af326 (diff) | |
download | linux-stable-322b72e0fd10101f2da8985b31b4af70f184bf79.tar.gz linux-stable-322b72e0fd10101f2da8985b31b4af70f184bf79.tar.bz2 linux-stable-322b72e0fd10101f2da8985b31b4af70f184bf79.zip |
x86/resctrl: Avoid redundant counter read in __mon_event_count()
__mon_event_count() does the per-RMID, per-domain work for
user-initiated event count reads and the initialization of new monitor
groups.
In the initialization case, after resctrl_arch_reset_rmid() calls
__rmid_read() to record an initial count for a new monitor group, it
immediately calls resctrl_arch_rmid_read(). This re-read of the hardware
counter is unnecessary and the following computations are ignored by the
caller during initialization.
Following return from resctrl_arch_reset_rmid(), just clear the
mbm_state and return. This involves moving the mbm_state lookup into the
rr->first case, as it's not needed for regular event count reads: the
QOS_L3_OCCUP_EVENT_ID case was redundant with the accumulating logic at
the end of the function.
Signed-off-by: Peter Newman <peternewman@google.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Reinette Chatre <reinette.chatre@intel.com>
Tested-by: Babu Moger <babu.moger@amd.com>
Link: https://lore.kernel.org/all/20221220164132.443083-2-peternewman%40google.com
Diffstat (limited to 'arch/x86/kernel/cpu')
-rw-r--r-- | arch/x86/kernel/cpu/resctrl/monitor.c | 43 |
1 files changed, 19 insertions, 24 deletions
diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c index 7fe51488e136..20952419be75 100644 --- a/arch/x86/kernel/cpu/resctrl/monitor.c +++ b/arch/x86/kernel/cpu/resctrl/monitor.c @@ -383,41 +383,36 @@ void free_rmid(u32 rmid) list_add_tail(&entry->list, &rmid_free_lru); } +static struct mbm_state *get_mbm_state(struct rdt_domain *d, u32 rmid, + enum resctrl_event_id evtid) +{ + switch (evtid) { + case QOS_L3_MBM_TOTAL_EVENT_ID: + return &d->mbm_total[rmid]; + case QOS_L3_MBM_LOCAL_EVENT_ID: + return &d->mbm_local[rmid]; + default: + return NULL; + } +} + static int __mon_event_count(u32 rmid, struct rmid_read *rr) { struct mbm_state *m; u64 tval = 0; - if (rr->first) + if (rr->first) { resctrl_arch_reset_rmid(rr->r, rr->d, rmid, rr->evtid); + m = get_mbm_state(rr->d, rmid, rr->evtid); + if (m) + memset(m, 0, sizeof(struct mbm_state)); + return 0; + } rr->err = resctrl_arch_rmid_read(rr->r, rr->d, rmid, rr->evtid, &tval); if (rr->err) return rr->err; - switch (rr->evtid) { - case QOS_L3_OCCUP_EVENT_ID: - rr->val += tval; - return 0; - case QOS_L3_MBM_TOTAL_EVENT_ID: - m = &rr->d->mbm_total[rmid]; - break; - case QOS_L3_MBM_LOCAL_EVENT_ID: - m = &rr->d->mbm_local[rmid]; - break; - default: - /* - * Code would never reach here because an invalid - * event id would fail in resctrl_arch_rmid_read(). - */ - return -EINVAL; - } - - if (rr->first) { - memset(m, 0, sizeof(struct mbm_state)); - return 0; - } - rr->val += tval; return 0; |