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Message-ID: <alpine.DEB.2.02.1210171304410.23243@vincent-weaver-1.um.maine.edu>
Date: Wed, 17 Oct 2012 13:05:45 -0400 (EDT)
From: Vince Weaver <vincent.weaver@...ne.edu>
To: linux-kernel@...r.kernel.org
cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>,
Paul Mackerras <paulus@...ba.org>,
Ingo Molnar <mingo@...hat.com>,
Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
eranian@...il.com,
"Meadows, Lawrence F" <lawrence.f.meadows@...el.com>
Subject: [PATCH 3/3] perf_event: Enable overflow on KNC with a custom
knc_pmu_handle_irq()
Although based on the P6 design, the interrupt mechnanism
for KNC more closely resembles the intel architectural perfmon one.
We can't just re-use that code though, because KNC has different
MSR numbers for the status and ack registers.
In this case we just cut-and paste from perf_event_intel.c
with some minor changes, as it looks like it would not be
worth the trouble to change that code to be MSR-configurable.
Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>
diff -ur linux-3.7-rc1.orig/arch/x86/kernel/cpu/perf_event_knc.c linux-3.7-rc1/arch/x86/kernel/cpu/perf_event_knc.c
--- linux-3.7-rc1.orig/arch/x86/kernel/cpu/perf_event_knc.c 2012-10-14 17:41:04.000000000 -0400
+++ linux-3.7-rc1/arch/x86/kernel/cpu/perf_event_knc.c 2012-10-17 12:11:48.604393067 -0400
@@ -3,6 +3,8 @@
#include <linux/perf_event.h>
#include <linux/types.h>
+#include <asm/hardirq.h>
+
#include "perf_event.h"
static const u64 knc_perfmon_event_map[] =
@@ -197,6 +199,80 @@
(void)wrmsrl_safe(hwc->config_base + hwc->idx, val);
}
+static inline u64 knc_pmu_get_status(void)
+{
+ u64 status;
+
+ rdmsrl(MSR_KNC_IA32_PERF_GLOBAL_STATUS, status);
+
+ return status;
+}
+
+static inline void knc_pmu_ack_status(u64 ack)
+{
+ wrmsrl(MSR_KNC_IA32_PERF_GLOBAL_OVF_CONTROL, ack);
+}
+
+static int knc_pmu_handle_irq(struct pt_regs *regs)
+{
+ struct perf_sample_data data;
+ struct cpu_hw_events *cpuc;
+ int bit, loops;
+ u64 status;
+ int handled=0;
+
+ cpuc = &__get_cpu_var(cpu_hw_events);
+
+ knc_pmu_disable_all();
+
+ status = knc_pmu_get_status();
+ if (!status) {
+ knc_pmu_enable_all(0);
+ return handled;
+ }
+
+ loops = 0;
+again:
+ knc_pmu_ack_status(status);
+ if (++loops > 100) {
+ WARN_ONCE(1, "perfevents: irq loop stuck!\n");
+ perf_event_print_debug();
+ goto done;
+ }
+
+ inc_irq_stat(apic_perf_irqs);
+
+ for_each_set_bit(bit, (unsigned long *)&status, X86_PMC_IDX_MAX) {
+ struct perf_event *event = cpuc->events[bit];
+
+ handled++;
+
+ if (!test_bit(bit, cpuc->active_mask))
+ continue;
+
+ if (!intel_pmu_save_and_restart(event))
+ continue;
+
+ perf_sample_data_init(&data, 0, event->hw.last_period);
+
+ if (perf_event_overflow(event, &data, regs))
+ x86_pmu_stop(event, 0);
+ }
+
+ /*
+ * Repeat if there is more work to be done:
+ */
+ status = knc_pmu_get_status();
+ if (status)
+ goto again;
+
+done:
+ knc_pmu_enable_all(0);
+
+ return handled;
+}
+
+
PMU_FORMAT_ATTR(event, "config:0-7" );
PMU_FORMAT_ATTR(umask, "config:8-15" );
PMU_FORMAT_ATTR(edge, "config:18" );
@@ -214,7 +290,7 @@
static __initconst struct x86_pmu knc_pmu = {
.name = "knc",
- .handle_irq = x86_pmu_handle_irq,
+ .handle_irq = knc_pmu_handle_irq,
.disable_all = knc_pmu_disable_all,
.enable_all = knc_pmu_enable_all,
.enable = knc_pmu_enable_event,
--
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