tests/functional/acpi-bits/bits-tests/smilatency.py2

# Copyright (c) 2015, Intel Corporation
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# SPDX-License-Identifier: BSD-3-Clause

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# This script runs only from the biosbits VM.

"""SMI latency test."""

import bits
from collections import namedtuple
import testsuite
import time
import usb

def register_tests():
     pass
#    testsuite.add_test("SMI latency test", smi_latency);
#    testsuite.add_test("SMI latency test with USB disabled via BIOS handoff", test_with_usb_disabled, runall=False);

def smi_latency():
    MSR_SMI_COUNT = 0x34

    print "Warning: touching the keyboard can affect the results of this test."

    tsc_per_sec = bits.tsc_per_sec()
    tsc_per_usec = tsc_per_sec / (1000 * 1000)
    bins = [long(tsc_per_usec * 10**i) for i in range(9)]
    bin_descs = [
        "0     < t <=   1us",
        "1us   < t <=  10us",
        "10us  < t <= 100us",
        "100us < t <=   1ms",
        "1ms   < t <=  10ms",
        "10ms  < t <= 100ms",
        "100ms < t <=   1s ",
        "1s    < t <=  10s ",
        "10s   < t <= 100s ",
        "100s  < t         ",
    ]

    print "Starting test. Wait here, I will be back in 15 seconds."
    (max_latency, smi_count_delta, bins) = bits.smi_latency(long(15 * tsc_per_sec), bins)
    BinType = namedtuple('BinType', ("max", "total", "count", "times"))
    bins = [BinType(*b) for b in bins]

    testsuite.test("SMI latency < 150us to minimize risk of OS timeouts", max_latency / tsc_per_usec <= 150)
    if not testsuite.show_detail():
        return

    for bin, desc in zip(bins, bin_descs):
        if bin.count == 0:
            continue
        testsuite.print_detail("{}; average = {}; count = {}".format(desc, bits.format_tsc(bin.total/bin.count), bin.count))
        deltas = (bits.format_tsc(t2 - t1) for t1,t2 in zip(bin.times, bin.times[1:]))
        testsuite.print_detail(" Times between first few observations: {}".format(" ".join("{:>6}".format(delta) for delta in deltas)))

    if smi_count_delta is not None:
        testsuite.print_detail("{} SMI detected using MSR_SMI_COUNT (MSR {:#x})".format(smi_count_delta, MSR_SMI_COUNT))

    testsuite.print_detail("Summary of impact: observed maximum latency = {}".format(bits.format_tsc(max_latency)))

def test_with_usb_disabled():
    if usb.handoff_to_os():
        smi_latency()

def average_io_smi(port, value, count):
    def f():
        tsc_start = bits.rdtsc()
        bits.outb(port, value)
        return bits.rdtsc() - tsc_start
    counts = [f() for i in range(count)]
    return sum(counts)/len(counts)

def time_io_smi(port=0xb2, value=0, count=1000):
    count_for_estimate = 10
    start = time.time()
    average_io_smi(port, value, count_for_estimate)
    avg10 = time.time() - start
    estimate = avg10 * count/count_for_estimate
    if estimate > 1:
        print "Running test, estimated time: {}s".format(int(estimate))
    average = average_io_smi(port, value, count)
    print "Average of {} SMIs (via outb, port={:#x}, value={:#x}): {}".format(count, port, value, bits.format_tsc(average))