On 10/12/2014 21:23, Marcelo Tosatti wrote:
>
> To test latency between TSC deadline timer
> interrupt injection.
>
> Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
>
> Index: kvm-unit-tests/config/config-x86-common.mak
> ===================================================================
> --- kvm-unit-tests.orig/config/config-x86-common.mak 2014-06-27 13:43:43.694257143 -0300
> +++ kvm-unit-tests/config/config-x86-common.mak 2014-12-10 16:10:41.715339378 -0200
> @@ -69,6 +69,8 @@
>
> $(TEST_DIR)/apic.elf: $(cstart.o) $(TEST_DIR)/apic.o
>
> +$(TEST_DIR)/tscdeadline-latency.elf: $(cstart.o) $(TEST_DIR)/tscdeadline-latency.o
> +
> $(TEST_DIR)/init.elf: $(cstart.o) $(TEST_DIR)/init.o
>
> $(TEST_DIR)/realmode.elf: $(TEST_DIR)/realmode.o
> Index: kvm-unit-tests/config/config-x86_64.mak
> ===================================================================
> --- kvm-unit-tests.orig/config/config-x86_64.mak 2014-12-10 16:03:20.609681443 -0200
> +++ kvm-unit-tests/config/config-x86_64.mak 2014-12-10 16:10:25.172352577 -0200
> @@ -9,5 +9,6 @@
> $(TEST_DIR)/pcid.flat $(TEST_DIR)/debug.flat
> tests += $(TEST_DIR)/svm.flat
> tests += $(TEST_DIR)/vmx.flat
> +tests += $(TEST_DIR)/tscdeadline-latency.flat
>
> include config/config-x86-common.mak
> Index: kvm-unit-tests/x86/tscdeadline-latency.c
> ===================================================================
> --- /dev/null 1970-01-01 00:00:00.000000000 +0000
> +++ kvm-unit-tests/x86/tscdeadline-latency.c 2014-12-10 18:21:38.151253344 -0200
> @@ -0,0 +1,110 @@
> +/*
> + * qemu command line | grep latency | cut -f 2 -d ":" > latency
> + *
> + * In octave:
> + * load latency
> + * min(list)
> + * max(list)
> + * mean(list)
> + * hist(latency, 50)
> + */
> +
> +#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);
> +}
> +
> +#define TSC_DEADLINE_TIMER_MODE (2 << 17)
> +#define TSC_DEADLINE_TIMER_VECTOR 0xef
> +#define MSR_IA32_TSC 0x00000010
> +#define MSR_IA32_TSCDEADLINE 0x000006e0
> +
> +static int tdt_count;
> +u64 exptime;
> +int delta;
> +#define TABLE_SIZE 10000
> +u64 table[TABLE_SIZE];
> +volatile int table_idx;
> +
> +static void tsc_deadline_timer_isr(isr_regs_t *regs)
> +{
> + u64 now = rdtsc();
> + ++tdt_count;
> +
> + if (table_idx < TABLE_SIZE && tdt_count > 1)
> + table[table_idx++] = now - exptime;
> +
> + exptime = now+delta;
> + wrmsr(MSR_IA32_TSCDEADLINE, now+delta);
> + apic_write(APIC_EOI, 0);
> +}
> +
> +static void start_tsc_deadline_timer(void)
> +{
> + handle_irq(TSC_DEADLINE_TIMER_VECTOR, tsc_deadline_timer_isr);
> + irq_enable();
> +
> + wrmsr(MSR_IA32_TSCDEADLINE, rdmsr(MSR_IA32_TSC)+delta);
> + asm volatile ("nop");
> +}
> +
> +static int enable_tsc_deadline_timer(void)
> +{
> + uint32_t lvtt;
> +
> + if (cpuid(1).c & (1 << 24)) {
> + lvtt = TSC_DEADLINE_TIMER_MODE | TSC_DEADLINE_TIMER_VECTOR;
> + apic_write(APIC_LVTT, lvtt);
> + start_tsc_deadline_timer();
> + return 1;
> + } else {
> + return 0;
> + }
> +}
> +
> +static void test_tsc_deadline_timer(void)
> +{
> + if(enable_tsc_deadline_timer()) {
> + printf("tsc deadline timer enabled\n");
> + } else {
> + printf("tsc deadline timer not detected\n");
> + }
> +}
> +
> +int main()
> +{
> + int i;
> +
> + setup_vm();
> + smp_init();
> + setup_idt();
> +
> + test_lapic_existence();
> +
> + mask_pic_interrupts();
> +
> + delta = 200000;
> + test_tsc_deadline_timer();
> + irq_enable();
> +
> + do {
> + asm volatile("hlt");
> + } while (table_idx < TABLE_SIZE);
> +
> + for (i = 0; i < TABLE_SIZE; i++)
> + printf("latency: %d\n", table[i]);
> +
> + return report_summary();
> +}
> Index: kvm-unit-tests/x86/unittests.cfg
> ===================================================================
> --- kvm-unit-tests.orig/x86/unittests.cfg 2014-12-10 16:03:20.616681437 -0200
> +++ kvm-unit-tests/x86/unittests.cfg 2014-12-10 16:15:23.145114609 -0200
> @@ -161,3 +161,8 @@
> [debug]
> file = debug.flat
> arch = x86_64
> +
> +[tscdeadline_latency]
> +file = tscdeadline_latency.flat
> +extra_params = -cpu qemu64,+tsc-deadline
> +arch = x86_64
> --
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>
Applied, thanks. Here is a script I use to run it:
#! /bin/sh
time ./x86/run x86/tscdeadline-latency.flat -cpu host | sed -n 's/^latency: //p' > l.txt
time ./x86/run x86/tscdeadline-latency.flat -append '2000000 4000' -cpu host | sed -n 's/^latency: //p' > l2.txt
time ./x86/run x86/tscdeadline-latency.flat -append '4000000 2000' -cpu host | sed -n 's/^latency: //p' > l3.txt
gnuplot << \EOF
hist(x,width)=width*floor(x/width) + binwidth/2.0
binwidth=500
set xrange [0:50000]
set boxwidth binwidth
set term png size 1024,512
set output "200000,10000.png"
plot 'l.txt' using (hist($1,binwidth)):(1.0/10000) smooth freq with boxes
binwidth=3000
set xrange [0:500000]
set boxwidth binwidth
set term png size 1024,512
set output "2000000,4000.png"
plot 'l2.txt' using (hist($1,binwidth)):(1.0/4000) smooth freq with boxes
binwidth=3000
set xrange [0:500000]
set boxwidth binwidth
set term png size 1024,512
set output "4000000,2000.png"
plot 'l3.txt' using (hist($1,binwidth)):(1.0/2000) smooth freq with boxes
EOF
and I attach the plots I get with a non-realtime kernel. I'll try a
realtime kernel tomorrow; in the meanwhile, can you attach the three
plots you get on your machine too (RT), so that we can be sure we're
looking at the same thing?
Paolo
Attachment:
200000,10000.png
Description: PNG image
Attachment:
2000000,4000.png
Description: PNG image
Attachment:
4000000,2000.png
Description: PNG image
