[PATCH v9 4/9] x86/resctrl: Compute memory bandwidth for all supported events

Tony Luck
2024-11-14T00:17:21Z

Computing the bandwidth for an event is cheap, and only done once
per second. Doing so simplifies switching between events and allows
choosing different events per ctrl_mon group.

Suggested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
---
arch/x86/kernel/cpu/resctrl/monitor.c | 72 ++++++++++++---------------
1 file changed, 33 insertions(+), 39 deletions(-)

diff --git a/arch/x86/kernel/cpu/resctrl/monitor.c b/arch/x86/kernel/cpu/resctrl/monitor.c
index 2176e355e864..da4ae21350c8 100644
--- a/arch/x86/kernel/cpu/resctrl/monitor.c
+++ b/arch/x86/kernel/cpu/resctrl/monitor.c
@@ -663,9 +663,12 @@ static int __mon_event_count(u32 closid, u32 rmid, struct rmid_read *rr)
*/
static void mbm_bw_count(u32 closid, u32 rmid, struct rmid_read *rr)
{
- u32 idx = resctrl_arch_rmid_idx_encode(closid, rmid);
- struct mbm_state *m = &rr->d->mbm_local[idx];
u64 cur_bw, bytes, cur_bytes;
+ struct mbm_state *m;
+
+ m = get_mbm_state(rr->d, closid, rmid, rr->evtid);
+ if (WARN_ON_ONCE(!m))
+ return;

cur_bytes = rr->val;
bytes = cur_bytes - m->prev_bw_bytes;
@@ -826,54 +829,45 @@ static void update_mba_bw(struct rdtgroup *rgrp, struct rdt_mon_domain *dom_mbm)
resctrl_arch_update_one(r_mba, dom_mba, closid, CDP_NONE, new_msr_val);
}

-static void mbm_update(struct rdt_resource *r, struct rdt_mon_domain *d,
- u32 closid, u32 rmid)
+static void mbm_update_one_event(struct rdt_resource *r, struct rdt_mon_domain *d,
+ u32 closid, u32 rmid, enum resctrl_event_id evtid)
{
struct rmid_read rr = {0};

rr.r = r;
rr.d = d;
+ rr.evtid = evtid;
+ rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);
+ if (IS_ERR(rr.arch_mon_ctx)) {
+ pr_warn_ratelimited("Failed to allocate monitor context: %ld",
+ PTR_ERR(rr.arch_mon_ctx));
+ return;
+ }
+
+ __mon_event_count(closid, rmid, &rr);

/*
- * This is protected from concurrent reads from user
- * as both the user and we hold the global mutex.
+ * If the software controller is enabled, compute the
+ * bandwidth for this event id.
*/
- if (is_mbm_total_enabled()) {
- rr.evtid = QOS_L3_MBM_TOTAL_EVENT_ID;
- rr.val = 0;
- rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);
- if (IS_ERR(rr.arch_mon_ctx)) {
- pr_warn_ratelimited("Failed to allocate monitor context: %ld",
- PTR_ERR(rr.arch_mon_ctx));
- return;
- }
-
- __mon_event_count(closid, rmid, &rr);
+ if (is_mba_sc(NULL))
+ mbm_bw_count(closid, rmid, &rr);

- resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
- }
- if (is_mbm_local_enabled()) {
- rr.evtid = QOS_L3_MBM_LOCAL_EVENT_ID;
- rr.val = 0;
- rr.arch_mon_ctx = resctrl_arch_mon_ctx_alloc(rr.r, rr.evtid);
- if (IS_ERR(rr.arch_mon_ctx)) {
- pr_warn_ratelimited("Failed to allocate monitor context: %ld",
- PTR_ERR(rr.arch_mon_ctx));
- return;
- }
-
- __mon_event_count(closid, rmid, &rr);
+ resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
+}

- /*
- * Call the MBA software controller only for the
- * control groups and when user has enabled
- * the software controller explicitly.
- */
- if (is_mba_sc(NULL))
- mbm_bw_count(closid, rmid, &rr);
+static void mbm_update(struct rdt_resource *r, struct rdt_mon_domain *d,
+ u32 closid, u32 rmid)
+{
+ /*
+ * This is protected from concurrent reads from user
+ * as both the user and we hold the global mutex.
+ */
+ if (is_mbm_total_enabled())
+ mbm_update_one_event(r, d, closid, rmid, QOS_L3_MBM_TOTAL_EVENT_ID);

- resctrl_arch_mon_ctx_free(rr.r, rr.evtid, rr.arch_mon_ctx);
- }
+ if (is_mbm_local_enabled())
+ mbm_update_one_event(r, d, closid, rmid, QOS_L3_MBM_LOCAL_EVENT_ID);
}

/*
--
2.47.0