RE: [PATCH V2 1/1] perf, Add support for Xeon-Phi PMU

From: Meadows, Lawrence F
Date: Tue Sep 25 2012 - 12:26:38 EST

I recommend that you use KNC. Xeon Phi is a marketing name. PMU for followon Xeon Phi chips will probably be different.

-----Original Message-----
From: Vince Weaver [mailto:vincent.weaver@xxxxxxxxx]
Sent: Tuesday, September 25, 2012 9:23 AM
To: linux-kernel@xxxxxxxxxxxxxxx
Cc: Peter Zijlstra; Cyrill Gorcunov; Paul Mackerras; Ingo Molnar; Arnaldo Carvalho de Melo; eranian@xxxxxxxxx; Meadows, Lawrence F
Subject: [PATCH V2 1/1] perf, Add support for Xeon-Phi PMU

Hello

This is an updated version of the patch. It uses ARCH_PERFMON_EVENTSEL_INT for the DATA_READ event, with the assumption that x86_pmu_hw_config() is going to set that bit anyway. This lets the code get through the test for an event being 0 without triggering -ENOENT.

One remaining question, is "Phi" a marketing name and should we find/replace all PHI with KNC for Knight's Corner?


Included below is a patch that adds perf support for the Xeon-Phi PMU,
as documented in the "Intel Xeon Phi Coprocessor (codename: Knights
Corner) Performance Monitoring Units" manual.

Even though it is a co-processor, a Phi runs a full Linux environment
and can support performance counters.

This is just barebones support, it does not add support for
interesting new features such as the SPFLT intruction that
allows starting/stopping events without entering the kernel.

The PMU internally is just like that of an original Pentium, but
a "P6-like" MSR interface is provided. The interface is different enough
from a real P6 that it's not easy (or practical) to re-use the code in
perf_event_p6.c


Signed-off-by: Vince Weaver <vincent.weaver@xxxxxxxxx>

diff -Nur linux-3.6-rc6/arch/x86/include/asm/msr-index.h linux-3.6-rc6-mic/arch/x86/include/asm/msr-index.h
--- linux-3.6-rc6/arch/x86/include/asm/msr-index.h 2012-09-16 17:58:51.000000000 -0400
+++ linux-3.6-rc6-mic/arch/x86/include/asm/msr-index.h 2012-09-20 11:55:14.854332191 -0400
@@ -121,6 +121,11 @@
#define MSR_P6_EVNTSEL0 0x00000186
#define MSR_P6_EVNTSEL1 0x00000187

+#define MSR_PHI_PERFCTR0 0x00000020
+#define MSR_PHI_PERFCTR1 0x00000021
+#define MSR_PHI_EVNTSEL0 0x00000028
+#define MSR_PHI_EVNTSEL1 0x00000029
+
/* AMD64 MSRs. Not complete. See the architecture manual for a more
complete list. */

diff -Nur linux-3.6-rc6/arch/x86/kernel/cpu/Makefile linux-3.6-rc6-mic/arch/x86/kernel/cpu/Makefile
--- linux-3.6-rc6/arch/x86/kernel/cpu/Makefile 2012-09-16 17:58:51.000000000 -0400
+++ linux-3.6-rc6-mic/arch/x86/kernel/cpu/Makefile 2012-09-20 12:15:21.042331190 -0400
@@ -32,7 +32,7 @@

ifdef CONFIG_PERF_EVENTS
obj-$(CONFIG_CPU_SUP_AMD) += perf_event_amd.o
-obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_p6.o perf_event_p4.o
+obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_p6.o perf_event_phi.o perf_event_p4.o
obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_intel_lbr.o perf_event_intel_ds.o perf_event_intel.o
obj-$(CONFIG_CPU_SUP_INTEL) += perf_event_intel_uncore.o
endif
diff -Nur linux-3.6-rc6/arch/x86/kernel/cpu/perfctr-watchdog.c linux-3.6-rc6-mic/arch/x86/kernel/cpu/perfctr-watchdog.c
--- linux-3.6-rc6/arch/x86/kernel/cpu/perfctr-watchdog.c 2012-09-16 17:58:51.000000000 -0400
+++ linux-3.6-rc6-mic/arch/x86/kernel/cpu/perfctr-watchdog.c 2012-09-20 11:56:51.430332108 -0400
@@ -56,6 +56,8 @@
switch (boot_cpu_data.x86) {
case 6:
return msr - MSR_P6_PERFCTR0;
+ case 11:
+ return msr - MSR_PHI_PERFCTR0;
case 15:
return msr - MSR_P4_BPU_PERFCTR0;
}
@@ -82,6 +84,8 @@
switch (boot_cpu_data.x86) {
case 6:
return msr - MSR_P6_EVNTSEL0;
+ case 11:
+ return msr - MSR_PHI_EVNTSEL0;
case 15:
return msr - MSR_P4_BSU_ESCR0;
}
diff -Nur linux-3.6-rc6/arch/x86/kernel/cpu/perf_event.h linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event.h
--- linux-3.6-rc6/arch/x86/kernel/cpu/perf_event.h 2012-09-16 17:58:51.000000000 -0400
+++ linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event.h 2012-09-20 12:49:25.782329486 -0400
@@ -624,6 +624,8 @@

int p6_pmu_init(void);

+int phi_pmu_init(void);
+
#else /* CONFIG_CPU_SUP_INTEL */

static inline void reserve_ds_buffers(void)
diff -Nur linux-3.6-rc6/arch/x86/kernel/cpu/perf_event_intel.c linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event_intel.c
--- linux-3.6-rc6/arch/x86/kernel/cpu/perf_event_intel.c 2012-09-16 17:58:51.000000000 -0400
+++ linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event_intel.c 2012-09-20 12:14:37.082331232 -0400
@@ -1906,6 +1906,8 @@
switch (boot_cpu_data.x86) {
case 0x6:
return p6_pmu_init();
+ case 0xb:
+ return phi_pmu_init();
case 0xf:
return p4_pmu_init();
}
diff -Nur linux-3.6-rc6/arch/x86/kernel/cpu/perf_event_phi.c linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event_phi.c
--- linux-3.6-rc6/arch/x86/kernel/cpu/perf_event_phi.c 1969-12-31 19:00:00.000000000 -0500
+++ linux-3.6-rc6-mic/arch/x86/kernel/cpu/perf_event_phi.c 2012-09-25 12:10:46.505972473 -0400
@@ -0,0 +1,246 @@
+#include <linux/perf_event.h>
+#include <linux/types.h>
+
+#include "perf_event.h"
+
+static const u64 phi_perfmon_event_map[] =
+{
+ [PERF_COUNT_HW_CPU_CYCLES] = 0x002a,
+ [PERF_COUNT_HW_INSTRUCTIONS] = 0x0016,
+ [PERF_COUNT_HW_CACHE_REFERENCES] = 0x0028,
+ [PERF_COUNT_HW_CACHE_MISSES] = 0x0029,
+ [PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = 0x0012,
+ [PERF_COUNT_HW_BRANCH_MISSES] = 0x002b,
+};
+
+static __initconst u64 phi_hw_cache_event_ids
+ [PERF_COUNT_HW_CACHE_MAX]
+ [PERF_COUNT_HW_CACHE_OP_MAX]
+ [PERF_COUNT_HW_CACHE_RESULT_MAX] =
+{
+ [ C(L1D) ] = {
+ [ C(OP_READ) ] = {
+ /* On Xeon Phi event "0" is a valid DATA_READ */
+ /* (L1 Data Cache Reads) Instruction. */
+ /* We code this as ARCH_PERFMON_EVENTSEL_INT as this */
+ /* bit will always be set in x86_pmu_hw_config(). */
+ [ C(RESULT_ACCESS) ] = ARCH_PERFMON_EVENTSEL_INT,
+ /* DATA_READ */
+ [ C(RESULT_MISS) ] = 0x0003, /* DATA_READ_MISS */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0001, /* DATA_WRITE */
+ [ C(RESULT_MISS) ] = 0x0004, /* DATA_WRITE_MISS */
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0011, /* L1_DATA_PF1 */
+ [ C(RESULT_MISS) ] = 0x001c, /* L1_DATA_PF1_MISS */
+ },
+ },
+ [ C(L1I ) ] = {
+ [ C(OP_READ) ] = {
+ [ C(RESULT_ACCESS) ] = 0x000c, /* CODE_READ */
+ [ C(RESULT_MISS) ] = 0x000e, /* CODE_CACHE_MISS */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = -1,
+ [ C(RESULT_MISS) ] = -1,
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0,
+ [ C(RESULT_MISS) ] = 0x0,
+ },
+ },
+ [ C(LL ) ] = {
+ [ C(OP_READ) ] = {
+ [ C(RESULT_ACCESS) ] = 0,
+ [ C(RESULT_MISS) ] = 0x10cb, /* L2_READ_MISS */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = 0x10cc, /* L2_WRITE_HIT */
+ [ C(RESULT_MISS) ] = 0,
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = 0x10fc, /* L2_DATA_PF2 */
+ [ C(RESULT_MISS) ] = 0x10fe, /* L2_DATA_PF2_MISS */
+ },
+ },
+ [ C(DTLB) ] = {
+ [ C(OP_READ) ] = {
+ [ C(RESULT_ACCESS) ] = ARCH_PERFMON_EVENTSEL_INT,
+ /* DATA_READ */
+ /* see note on L1 OP_READ */
+ [ C(RESULT_MISS) ] = 0x0002, /* DATA_PAGE_WALK */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0001, /* DATA_WRITE */
+ [ C(RESULT_MISS) ] = 0x0002, /* DATA_PAGE_WALK */
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0,
+ [ C(RESULT_MISS) ] = 0x0,
+ },
+ },
+ [ C(ITLB) ] = {
+ [ C(OP_READ) ] = {
+ [ C(RESULT_ACCESS) ] = 0x000c, /* CODE_READ */
+ [ C(RESULT_MISS) ] = 0x000d, /* CODE_PAGE_WALK */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = -1,
+ [ C(RESULT_MISS) ] = -1,
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = -1,
+ [ C(RESULT_MISS) ] = -1,
+ },
+ },
+ [ C(BPU ) ] = {
+ [ C(OP_READ) ] = {
+ [ C(RESULT_ACCESS) ] = 0x0012, /* BRANCHES */
+ [ C(RESULT_MISS) ] = 0x002b, /* BRANCHES_MISPREDICTED */
+ },
+ [ C(OP_WRITE) ] = {
+ [ C(RESULT_ACCESS) ] = -1,
+ [ C(RESULT_MISS) ] = -1,
+ },
+ [ C(OP_PREFETCH) ] = {
+ [ C(RESULT_ACCESS) ] = -1,
+ [ C(RESULT_MISS) ] = -1,
+ },
+ },
+};
+
+
+static u64 phi_pmu_event_map(int hw_event)
+{
+ return phi_perfmon_event_map[hw_event];
+}
+
+static struct event_constraint phi_event_constraints[] =
+{
+ INTEL_EVENT_CONSTRAINT(0xc3, 0x1), /* HWP_L2HIT */
+ INTEL_EVENT_CONSTRAINT(0xc4, 0x1), /* HWP_L2MISS */
+ INTEL_EVENT_CONSTRAINT(0xc8, 0x1), /* L2_READ_HIT_E */
+ INTEL_EVENT_CONSTRAINT(0xc9, 0x1), /* L2_READ_HIT_M */
+ INTEL_EVENT_CONSTRAINT(0xca, 0x1), /* L2_READ_HIT_S */
+ INTEL_EVENT_CONSTRAINT(0xcb, 0x1), /* L2_READ_MISS */
+ INTEL_EVENT_CONSTRAINT(0xcc, 0x1), /* L2_WRITE_HIT */
+ INTEL_EVENT_CONSTRAINT(0xce, 0x1), /* L2_STRONGLY_ORDERED_STREAMING_VSTORES_MISS */
+ INTEL_EVENT_CONSTRAINT(0xcf, 0x1), /* L2_WEAKLY_ORDERED_STREAMING_VSTORE_MISS */
+ INTEL_EVENT_CONSTRAINT(0xd7, 0x1), /* L2_VICTIM_REQ_WITH_DATA */
+ INTEL_EVENT_CONSTRAINT(0xe3, 0x1), /* SNP_HITM_BUNIT */
+ INTEL_EVENT_CONSTRAINT(0xe6, 0x1), /* SNP_HIT_L2 */
+ INTEL_EVENT_CONSTRAINT(0xe7, 0x1), /* SNP_HITM_L2 */
+ INTEL_EVENT_CONSTRAINT(0xf1, 0x1), /* L2_DATA_READ_MISS_CACHE_FILL */
+ INTEL_EVENT_CONSTRAINT(0xf2, 0x1), /* L2_DATA_WRITE_MISS_CACHE_FILL */
+ INTEL_EVENT_CONSTRAINT(0xf6, 0x1), /* L2_DATA_READ_MISS_MEM_FILL */
+ INTEL_EVENT_CONSTRAINT(0xf7, 0x1), /* L2_DATA_WRITE_MISS_MEM_FILL */
+ INTEL_EVENT_CONSTRAINT(0xfc, 0x1), /* L2_DATA_PF2 */
+ INTEL_EVENT_CONSTRAINT(0xfd, 0x1), /* L2_DATA_PF2_DROP */
+ INTEL_EVENT_CONSTRAINT(0xfe, 0x1), /* L2_DATA_PF2_MISS */
+ INTEL_EVENT_CONSTRAINT(0xff, 0x1), /* L2_DATA_HIT_INFLIGHT_PF2 */
+ EVENT_CONSTRAINT_END
+};
+
+#define MSR_PHI_IA32_PERF_GLOBAL_STATUS 0x0000002d
+#define MSR_PHI_IA32_PERF_GLOBAL_OVF_CONTROL 0x0000002e
+#define MSR_PHI_IA32_PERF_GLOBAL_CTRL 0x0000002f
+
+#define PHI_ENABLE_COUNTER0 0x00000001
+#define PHI_ENABLE_COUNTER1 0x00000002
+
+static void phi_pmu_disable_all(void)
+{
+ u64 val;
+
+ rdmsrl(MSR_PHI_IA32_PERF_GLOBAL_CTRL, val);
+ val &= ~(PHI_ENABLE_COUNTER0|PHI_ENABLE_COUNTER1);
+ wrmsrl(MSR_PHI_IA32_PERF_GLOBAL_CTRL, val);
+}
+
+static void phi_pmu_enable_all(int added)
+{
+ u64 val;
+
+ rdmsrl(MSR_PHI_IA32_PERF_GLOBAL_CTRL, val);
+ val |= (PHI_ENABLE_COUNTER0|PHI_ENABLE_COUNTER1);
+ wrmsrl(MSR_PHI_IA32_PERF_GLOBAL_CTRL, val);
+}
+
+static inline void
+phi_pmu_disable_event(struct perf_event *event)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ u64 val;
+
+ val = hwc->config;
+ if (cpuc->enabled)
+ val &= ~ARCH_PERFMON_EVENTSEL_ENABLE;
+
+ (void)wrmsrl_safe(hwc->config_base + hwc->idx, val);
+}
+
+static void phi_pmu_enable_event(struct perf_event *event)
+{
+ struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events);
+ struct hw_perf_event *hwc = &event->hw;
+ u64 val;
+
+ val = hwc->config;
+ if (cpuc->enabled)
+ val |= ARCH_PERFMON_EVENTSEL_ENABLE;
+
+ (void)wrmsrl_safe(hwc->config_base + hwc->idx, val);
+}
+
+PMU_FORMAT_ATTR(event, "config:0-7" );
+PMU_FORMAT_ATTR(umask, "config:8-15" );
+PMU_FORMAT_ATTR(edge, "config:18" );
+PMU_FORMAT_ATTR(inv, "config:23" );
+PMU_FORMAT_ATTR(cmask, "config:24-31" );
+
+static struct attribute *intel_phi_formats_attr[] = {
+ &format_attr_event.attr,
+ &format_attr_umask.attr,
+ &format_attr_edge.attr,
+ &format_attr_inv.attr,
+ &format_attr_cmask.attr,
+ NULL,
+};
+
+static __initconst struct x86_pmu phi_pmu = {
+ .name = "phi",
+ .handle_irq = x86_pmu_handle_irq,
+ .disable_all = phi_pmu_disable_all,
+ .enable_all = phi_pmu_enable_all,
+ .enable = phi_pmu_enable_event,
+ .disable = phi_pmu_disable_event,
+ .hw_config = x86_pmu_hw_config,
+ .schedule_events = x86_schedule_events,
+ .eventsel = MSR_PHI_EVNTSEL0,
+ .perfctr = MSR_PHI_PERFCTR0,
+ .event_map = phi_pmu_event_map,
+ .max_events = ARRAY_SIZE(phi_perfmon_event_map),
+ .apic = 1,
+ .max_period = (1ULL << 31) - 1,
+ .version = 0,
+ .num_counters = 2,
+ /* in theory 40 bits, early silicon is buggy though */
+ .cntval_bits = 32,
+ .cntval_mask = (1ULL << 32) - 1,
+ .get_event_constraints = x86_get_event_constraints,
+ .event_constraints = phi_event_constraints,
+ .format_attrs = intel_phi_formats_attr,
+};
+
+__init int phi_pmu_init(void)
+{
+ x86_pmu = phi_pmu;
+
+ memcpy(hw_cache_event_ids, phi_hw_cache_event_ids,
+ sizeof(hw_cache_event_ids));
+
+ return 0;
+}
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