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authorPeter Newman <peternewman@google.com>2022-12-20 19:41:32 +0300
committerDave Hansen <dave.hansen@linux.intel.com>2023-03-16 01:44:15 +0300
commit322b72e0fd10101f2da8985b31b4af70f184bf79 (patch)
tree5ae8dcbf8f5e5d96b951eb7d207a0f4f256c3123 /arch
parenteeac8ede17557680855031c6f305ece2378af326 (diff)
downloadlinux-322b72e0fd10101f2da8985b31b4af70f184bf79.tar.xz
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')
-rw-r--r--arch/x86/kernel/cpu/resctrl/monitor.c43
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;