[PATCH] x86: apic: add APIC Timer periodic/oneshot mode latency test

* [PATCH] x86: apic: add APIC Timer periodic/oneshot mode latency test
@ 2016-10-17  8:28 Wanpeng Li
  2016-10-25 11:55 ` Radim Krčmář
  0 siblings, 1 reply; 5+ messages in thread
From: Wanpeng Li @ 2016-10-17  8:28 UTC (permalink / raw)
  To: kvm; +Cc: Wanpeng Li, Paolo Bonzini, Radim Krčmář

From: Wanpeng Li <wanpeng.li@hotmail.com>

Add APIC Timer periodic/oneshot mode latency test.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
 x86/Makefile.x86_64      |   1 +
 x86/apic_timer_latency.c | 125 +++++++++++++++++++++++++++++++++++++++++++++++
 x86/unittests.cfg        |   6 +++
 3 files changed, 132 insertions(+)
 create mode 100644 x86/apic_timer_latency.c

diff --git a/x86/Makefile.x86_64 b/x86/Makefile.x86_64
index e166911..c9eda46 100644
--- a/x86/Makefile.x86_64
+++ b/x86/Makefile.x86_64
@@ -14,6 +14,7 @@ tests = $(TEST_DIR)/access.flat $(TEST_DIR)/apic.flat \
 tests += $(TEST_DIR)/svm.flat
 tests += $(TEST_DIR)/vmx.flat
 tests += $(TEST_DIR)/tscdeadline_latency.flat
+tests += $(TEST_DIR)/apic_timer_latency.flat
 
 include $(TEST_DIR)/Makefile.common
 
diff --git a/x86/apic_timer_latency.c b/x86/apic_timer_latency.c
new file mode 100644
index 0000000..4dd285f
--- /dev/null
+++ b/x86/apic_timer_latency.c
@@ -0,0 +1,125 @@
+/*
+ * qemu command line | grep latency | cut -f 2 -d ":" > latency
+ *
+ * In octave:
+ * load latency
+ * min(latency)
+ * max(latency)
+ * mean(latency)
+ * hist(latency, 50)
+ */
+
+/*
+ * for host tracing of breakmax option:
+ *
+ * # cd /sys/kernel/debug/tracing/
+ * # echo x86-tsc > trace_clock
+ * # echo "kvm_exit kvm_entry kvm_msr" > set_event
+ * # echo "sched_switch $extratracepoints" >> set_event
+ * # echo apic_timer_fn > set_ftrace_filter
+ * # echo "function" > current_tracer
+ */
+
+#include "libcflat.h"
+#include "apic.h"
+#include "vm.h"
+#include "smp.h"
+#include "desc.h"
+#include "isr.h"
+#include "msr.h"
+
+static void test_lapic_existence(void)
+{
+    u32 lvr;
+
+    lvr = apic_read(APIC_LVR);
+    printf("apic version: %x\n", lvr);
+    report("apic existence", (u16)lvr == 0x14);
+}
+
+static int tdt_count;
+u64 exptime;
+int delta;
+int mode;
+#define TABLE_SIZE 100000
+u64 table[TABLE_SIZE];
+volatile int table_idx;
+volatile int hitmax = 0;
+int breakmax = 0;
+#define APIC_LVT_TIMER_ONE_SHOT  (0)
+#define APIC_LVT_TIMER_VECTOR (0xee)
+
+static void apic_timer_isr(isr_regs_t *regs)
+{
+    u64 now = rdtsc();
+    ++tdt_count;
+
+    if (table_idx < TABLE_SIZE && tdt_count > 1)
+        table[table_idx++] = now - exptime;
+
+    if (breakmax && tdt_count > 1 && (now - exptime) > breakmax) {
+        hitmax = 1;
+        apic_write(APIC_EOI, 0);
+        return;
+    }
+
+    exptime = now+delta;
+
+    if (mode == APIC_LVT_TIMER_ONE_SHOT)
+        /* Set "Initial Counter Register", which starts the timer */
+        apic_write(APIC_TMICT, delta);
+
+    apic_write(APIC_EOI, 0);
+}
+
+static void test_apic_timer(int mode)
+{
+    handle_irq(APIC_LVT_TIMER_VECTOR, apic_timer_isr);
+    irq_enable();
+
+	/* Periodic mode */
+    apic_write(APIC_LVTT, mode | APIC_LVT_TIMER_VECTOR);
+    /* Divider == 1 */
+    apic_write(APIC_TDCR, 0x0000000b);
+    apic_write(APIC_TMICT, delta);
+}
+
+int main(int argc, char **argv)
+{
+    int i, size;
+    u64 count = 0;
+
+    setup_vm();
+    smp_init();
+    setup_idt();
+
+    test_lapic_existence();
+
+    mask_pic_interrupts();
+
+    mode = argc <= 1 ? APIC_LVT_TIMER_PERIODIC : atol(argv[1]);
+    delta = argc <= 2 ? 0x100000 : atol(argv[2]);
+    size = argc <= 3 ? TABLE_SIZE : atol(argv[3]);
+    breakmax = argc <= 4 ? 0 : atol(argv[4]);
+    printf("breakmax=%d\n", breakmax);
+    if (mode == APIC_LVT_TIMER_PERIODIC)
+        printf("APIC Timer Periodic Mode\n");
+    else if (mode == APIC_LVT_TIMER_ONE_SHOT)
+        printf("APIC Timer Oneshot Mode\n");
+    test_apic_timer(mode);
+    irq_enable();
+
+    do {
+        asm volatile("hlt");
+    } while (!hitmax && table_idx < size);
+
+    for (i = 0; i < table_idx; i++) {
+        if (hitmax && i == table_idx-1)
+            printf("hit max: %d < ", breakmax);
+        count += table[i];
+        printf("latency: %" PRId64 "\n", table[i]);
+    }
+
+    printf("average latency = %lu\n", count/size);
+    return report_summary();
+}
diff --git a/x86/unittests.cfg b/x86/unittests.cfg
index 7242517..e055ce1 100644
--- a/x86/unittests.cfg
+++ b/x86/unittests.cfg
@@ -32,6 +32,12 @@ extra_params = -cpu qemu64,+x2apic,+tsc-deadline
 arch = x86_64
 timeout = 30
 
+[apic_timer_latency]
+file = apic_timer_latency.flat
+smp = 1
+arch = x86_64
+timeout = 30
+
 [ioapic]
 file = ioapic.flat
 extra_params = -cpu qemu64
-- 
1.9.1


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