On 10/12/2014 21:23, Marcelo Tosatti wrote: > > To test latency between TSC deadline timer > interrupt injection. > > Signed-off-by: Marcelo Tosatti <[email protected]> > > 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 > -- > To unsubscribe from this list: send the line "unsubscribe kvm" in > the body of a message to [email protected] > More majordomo info at http://vger.kernel.org/majordomo-info.html >
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
