This can provide hints why latencies are not as low as expected, even without any hypervisor exits.
Signed-off-by: Jan Kiszka <[email protected]> --- Changes in v3 - tuned CPU list according to Ralf's feedback inmates/demos/x86/apic-demo.c | 46 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 45 insertions(+), 1 deletion(-) diff --git a/inmates/demos/x86/apic-demo.c b/inmates/demos/x86/apic-demo.c index ce03872e..5100cebd 100644 --- a/inmates/demos/x86/apic-demo.c +++ b/inmates/demos/x86/apic-demo.c @@ -12,24 +12,62 @@ #include <inmate.h> +#define MSR_SMI_COUNT 0x34 + #define POLLUTE_CACHE_SIZE (512 * 1024) #define APIC_TIMER_VECTOR 32 static unsigned long expected_time; static unsigned long min = -1, max; +static bool has_smi_count; +static u32 initial_smis; + +static const unsigned int smi_count_models[] = { + 0x37, 0x4a, 0x4d, 0x5a, 0x5d, 0x5c, 0x7a, /* Silvermont */ + 0x1a, 0x1e, 0x1f, 0x2e, /* Nehalem */ + 0x2a, 0x2d, /* Sandy Bridge */ + 0x57, 0x85, /* Xeon Phi */ + 0 +}; + +static bool cpu_has_smi_count(void) +{ + unsigned int family, model, smi_count_model, n = 0; + unsigned long eax; + + asm volatile("cpuid" : "=a" (eax) : "a" (1) + : "rbx", "rcx", "rdx", "memory"); + family = ((eax & 0xf00) >> 8) | ((eax & 0xff00000) >> 16); + model = ((eax & 0xf0) >> 4) | ((eax & 0xf0000) >> 12); + if (family == 0x6) { + do { + smi_count_model = smi_count_models[n++]; + if (model == smi_count_model) + return true; + } while (smi_count_model != 0); + } + return false; +} static void irq_handler(void) { unsigned long delta; + u32 smis; delta = tsc_read() - expected_time; if (delta < min) min = delta; if (delta > max) max = delta; - printk("Timer fired, jitter: %6ld ns, min: %6ld ns, max: %6ld ns\n", + printk("Timer fired, jitter: %6ld ns, min: %6ld ns, max: %6ld ns", delta, min, max); + if (has_smi_count) { + smis = (u32)read_msr(MSR_SMI_COUNT); + if (smis != initial_smis) + printk(", SMIs: %d", smis - initial_smis); + } + printk("\n"); expected_time += 100 * NS_PER_MSEC; apic_timer_set(expected_time - tsc_read()); @@ -80,6 +118,12 @@ void inmate_main(void) printk("Cache pollution enabled\n"); } + has_smi_count = cpu_has_smi_count(); + if (has_smi_count) { + initial_smis = (u32)read_msr(MSR_SMI_COUNT); + printk("Initial number of SMIs: %d\n", initial_smis); + } + tsc_freq = tsc_init(); printk("Calibrated TSC frequency: %lu.%03lu kHz\n", tsc_freq / 1000, tsc_freq % 1000); -- 2.16.4 -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
