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Message-Id: <1461905018-86355-3-git-send-email-davidcc@google.com>
Date: Thu, 28 Apr 2016 21:43:08 -0700
From: David Carrillo-Cisneros <davidcc@...gle.com>
To: Peter Zijlstra <peterz@...radead.org>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Ingo Molnar <mingo@...hat.com>
Cc: Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
Matt Fleming <matt.fleming@...el.com>,
Tony Luck <tony.luck@...el.com>,
Stephane Eranian <eranian@...gle.com>,
Paul Turner <pjt@...gle.com>,
David Carrillo-Cisneros <davidcc@...gle.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 02/32] perf/x86/intel/cqm: remove check for conflicting events
The new version of Intel's CQM uses a RMID hierarchy to avoid conflicts
between cpu, cgroup and task events, making unnecessary to check and
resolve conflicts between events of different types (ie. cgroup vs task).
Reviewed-by: Stephane Eranian <eranian@...gle.com>
Signed-off-by: David Carrillo-Cisneros <davidcc@...gle.com>
---
arch/x86/events/intel/cqm.c | 148 --------------------------------------------
1 file changed, 148 deletions(-)
diff --git a/arch/x86/events/intel/cqm.c b/arch/x86/events/intel/cqm.c
index 1b064c4..a3fde49 100644
--- a/arch/x86/events/intel/cqm.c
+++ b/arch/x86/events/intel/cqm.c
@@ -304,92 +304,6 @@ static inline struct perf_cgroup *event_to_cgroup(struct perf_event *event)
}
#endif
-/*
- * Determine if @a's tasks intersect with @b's tasks
- *
- * There are combinations of events that we explicitly prohibit,
- *
- * PROHIBITS
- * system-wide -> cgroup and task
- * cgroup -> system-wide
- * -> task in cgroup
- * task -> system-wide
- * -> task in cgroup
- *
- * Call this function before allocating an RMID.
- */
-static bool __conflict_event(struct perf_event *a, struct perf_event *b)
-{
-#ifdef CONFIG_CGROUP_PERF
- /*
- * We can have any number of cgroups but only one system-wide
- * event at a time.
- */
- if (a->cgrp && b->cgrp) {
- struct perf_cgroup *ac = a->cgrp;
- struct perf_cgroup *bc = b->cgrp;
-
- /*
- * This condition should have been caught in
- * __match_event() and we should be sharing an RMID.
- */
- WARN_ON_ONCE(ac == bc);
-
- if (cgroup_is_descendant(ac->css.cgroup, bc->css.cgroup) ||
- cgroup_is_descendant(bc->css.cgroup, ac->css.cgroup))
- return true;
-
- return false;
- }
-
- if (a->cgrp || b->cgrp) {
- struct perf_cgroup *ac, *bc;
-
- /*
- * cgroup and system-wide events are mutually exclusive
- */
- if ((a->cgrp && !(b->attach_state & PERF_ATTACH_TASK)) ||
- (b->cgrp && !(a->attach_state & PERF_ATTACH_TASK)))
- return true;
-
- /*
- * Ensure neither event is part of the other's cgroup
- */
- ac = event_to_cgroup(a);
- bc = event_to_cgroup(b);
- if (ac == bc)
- return true;
-
- /*
- * Must have cgroup and non-intersecting task events.
- */
- if (!ac || !bc)
- return false;
-
- /*
- * We have cgroup and task events, and the task belongs
- * to a cgroup. Check for for overlap.
- */
- if (cgroup_is_descendant(ac->css.cgroup, bc->css.cgroup) ||
- cgroup_is_descendant(bc->css.cgroup, ac->css.cgroup))
- return true;
-
- return false;
- }
-#endif
- /*
- * If one of them is not a task, same story as above with cgroups.
- */
- if (!(a->attach_state & PERF_ATTACH_TASK) ||
- !(b->attach_state & PERF_ATTACH_TASK))
- return true;
-
- /*
- * Must be non-overlapping.
- */
- return false;
-}
-
struct rmid_read {
u32 rmid;
atomic64_t value;
@@ -465,10 +379,6 @@ static void intel_cqm_stable(void *arg)
}
}
-/*
- * If we have group events waiting for an RMID that don't conflict with
- * events already running, assign @rmid.
- */
static bool intel_cqm_sched_in_event(u32 rmid)
{
struct perf_event *leader, *event;
@@ -484,9 +394,6 @@ static bool intel_cqm_sched_in_event(u32 rmid)
if (__rmid_valid(event->hw.cqm_rmid))
continue;
- if (__conflict_event(event, leader))
- continue;
-
intel_cqm_xchg_rmid(event, rmid);
return true;
}
@@ -592,10 +499,6 @@ static bool intel_cqm_rmid_stabilize(unsigned int *available)
continue;
}
- /*
- * If we have groups waiting for RMIDs, hand
- * them one now provided they don't conflict.
- */
if (intel_cqm_sched_in_event(entry->rmid))
continue;
@@ -638,46 +541,8 @@ static void __intel_cqm_pick_and_rotate(struct perf_event *next)
}
/*
- * Deallocate the RMIDs from any events that conflict with @event, and
- * place them on the back of the group list.
- */
-static void intel_cqm_sched_out_conflicting_events(struct perf_event *event)
-{
- struct perf_event *group, *g;
- u32 rmid;
-
- lockdep_assert_held(&cache_mutex);
-
- list_for_each_entry_safe(group, g, &cache_groups, hw.cqm_groups_entry) {
- if (group == event)
- continue;
-
- rmid = group->hw.cqm_rmid;
-
- /*
- * Skip events that don't have a valid RMID.
- */
- if (!__rmid_valid(rmid))
- continue;
-
- /*
- * No conflict? No problem! Leave the event alone.
- */
- if (!__conflict_event(group, event))
- continue;
-
- intel_cqm_xchg_rmid(group, INVALID_RMID);
- __put_rmid(rmid);
- }
-}
-
-/*
* Attempt to rotate the groups and assign new RMIDs.
*
- * We rotate for two reasons,
- * 1. To handle the scheduling of conflicting events
- * 2. To recycle RMIDs
- *
* Rotating RMIDs is complicated because the hardware doesn't give us
* any clues.
*
@@ -732,10 +597,6 @@ again:
goto stabilize;
/*
- * We have more event groups without RMIDs than available RMIDs,
- * or we have event groups that conflict with the ones currently
- * scheduled.
- *
* We force deallocate the rmid of the group at the head of
* cache_groups. The first event group without an RMID then gets
* assigned intel_cqm_rotation_rmid. This ensures we always make
@@ -754,8 +615,6 @@ again:
intel_cqm_xchg_rmid(start, intel_cqm_rotation_rmid);
intel_cqm_rotation_rmid = __get_rmid();
- intel_cqm_sched_out_conflicting_events(start);
-
if (__intel_cqm_threshold)
__intel_cqm_threshold--;
}
@@ -858,13 +717,6 @@ static void intel_cqm_setup_event(struct perf_event *event,
*group = iter;
return;
}
-
- /*
- * We only care about conflicts for events that are
- * actually scheduled in (and hence have a valid RMID).
- */
- if (__conflict_event(iter, event) && __rmid_valid(rmid))
- conflict = true;
}
if (conflict)
--
2.8.0.rc3.226.g39d4020
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