litespeed-quic/tests/test_bw_sampler.c
2022-05-06 12:49:46 -04:00

644 lines
20 KiB
C

/* Copyright (c) 2017 - 2022 LiteSpeed Technologies Inc. See LICENSE. */
/* Test adapted from Chromium bandwidth_sampler_test.cc */
// Copyright 2016 The Chromium Authors. All rights reserved.
#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <string.h>
#include <sys/queue.h>
#include "lsquic.h"
#include "lsquic_int_types.h"
#include "lsquic_hash.h"
#include "lsquic_packet_common.h"
#include "lsquic_packet_out.h"
#include "lsquic_bw_sampler.h"
#include "lsquic_conn.h"
#include "lsquic_malo.h"
/* Convert seconds to microseconds */
#define sec(val) ((val) * 1000 * 1000)
/* Convert milliseconds to lsquic_time_t, which is microseconds */
#define ms(val) ((val) * 1000)
/* Microseconds */
#define us(val) (val)
#define kRegularPacketSize 1280
#define PacketsToBytes(count_) ((count_) * kRegularPacketSize)
#define FromKBytesPerSecond(size_) (size_ * 8000)
// Enforce divisibility for some of the tests:
// "kRegularPacketSize has to be five times divisible by 2"
typedef char packet_size_has_to_be_five_times_divisible_by_2[
(kRegularPacketSize & 31) == 0 ? 1 : -1];
struct sampler_test
{
struct bw_sampler sampler;
lsquic_time_t time;
uint64_t bytes_in_flight;
struct lsquic_conn conn;
struct malo *malo_po;
};
static void
sampler_test_init (struct sampler_test *stest)
{
memset(stest, 0, sizeof(*stest));
stest->time = ms(1000); /* Time must not be zero, or test breaks */
LSCONN_INITIALIZE(&stest->conn);
lsquic_bw_sampler_init(&stest->sampler, &stest->conn, QUIC_FTBIT_STREAM);
stest->malo_po = lsquic_malo_create(sizeof(struct lsquic_packet_out));
assert(stest->malo_po);
}
static void
sampler_test_cleanup (struct sampler_test *stest)
{
lsquic_bw_sampler_cleanup(&stest->sampler);
lsquic_malo_destroy(stest->malo_po);
}
static struct lsquic_packet_out *
sampler_test_send_packet (struct sampler_test *stest, lsquic_packno_t packno,
bool retx)
{
struct lsquic_packet_out *packet_out;
packet_out = lsquic_malo_get(stest->malo_po);
assert(packet_out);
memset(packet_out, 0, sizeof(*packet_out));
packet_out->po_packno = packno;
packet_out->po_flags |= PO_SENT_SZ;
packet_out->po_flags |= PO_HELLO; /* Bypass sanity check */
packet_out->po_sent_sz = kRegularPacketSize;
packet_out->po_sent = stest->time;
if (retx)
packet_out->po_frame_types |= QUIC_FTBIT_STREAM;
lsquic_bw_sampler_packet_sent(&stest->sampler, packet_out,
stest->bytes_in_flight);
if (retx)
stest->bytes_in_flight += packet_out->po_sent_sz;
return packet_out;
}
static struct bw_sample *
sampler_test_ack_packet (struct sampler_test *stest,
struct lsquic_packet_out *packet_out)
{
if (packet_out->po_frame_types & QUIC_FTBIT_STREAM)
stest->bytes_in_flight -= packet_out->po_sent_sz;
return lsquic_bw_sampler_packet_acked(&stest->sampler, packet_out,
stest->time);
}
static void
sampler_test_lose_packet (struct sampler_test *stest,
struct lsquic_packet_out *packet_out)
{
if (packet_out->po_frame_types & QUIC_FTBIT_STREAM)
stest->bytes_in_flight -= packet_out->po_sent_sz;
lsquic_bw_sampler_packet_lost(&stest->sampler, packet_out);
}
static void
sampler_test_send_40_packets_and_ack_first_20 (struct sampler_test *stest,
lsquic_time_t time_between_packets, struct lsquic_packet_out *packets[])
{
struct bw_sample *sample;
unsigned i;
// Send 20 packets at a constant inter-packet time.
for (i = 1; i <= 20; i++)
{
packets[i] = sampler_test_send_packet(stest, i, true);
stest->time += time_between_packets;
}
// Ack packets 1 to 20, while sending new packets at the same rate as
// before.
for (i = 1; i <= 20; i++)
{
sample = sampler_test_ack_packet(stest, packets[i]);
assert(sample);
lsquic_malo_put(sample);
packets[i + 20] = sampler_test_send_packet(stest, i + 20, true);
stest->time += time_between_packets;
}
}
// Test the sampler in a simple stop-and-wait sender setting.
static void
test_send_and_wait (void)
{
struct sampler_test stest;
lsquic_time_t time_between_packets = ms(10);
uint64_t expected_bandwidth = kRegularPacketSize * 100 * 8;
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packet;
sampler_test_init(&stest);
// Send packets at the constant bandwidth.
for (i = 1; i < 20; ++i)
{
packet = sampler_test_send_packet(&stest, i, true);
stest.time += time_between_packets;
sample = sampler_test_ack_packet(&stest, packet);
assert(sample);
assert(expected_bandwidth == BW_VALUE(&sample->bandwidth));
lsquic_malo_put(sample);
}
// Send packets at the exponentially decreasing bandwidth.
for (i = 20; i < 25; i++)
{
time_between_packets = time_between_packets * 2;
expected_bandwidth = expected_bandwidth / 2;
packet = sampler_test_send_packet(&stest, i, true);
stest.time += time_between_packets;
sample = sampler_test_ack_packet(&stest, packet);
assert(sample);
assert(expected_bandwidth == BW_VALUE(&sample->bandwidth));
lsquic_malo_put(sample);
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
static void
test_send_time_state (void)
{
struct sampler_test stest;
lsquic_time_t time_between_packets = ms(10);
struct bw_sample *sample;
unsigned i;
struct lsquic_packet_out *packets[11];
sampler_test_init(&stest);
// Send packets 1-5.
for (i = 1; i <= 5; i++) {
packets[i] = sampler_test_send_packet(&stest, i, true);
assert(PacketsToBytes(i) == stest.sampler.bws_total_sent);
stest.time += time_between_packets;
}
/* The order of tests here is different. Because the send state is
* deleted when packet is acked, we have to check its values first.
*/
#define SEND_STATE(idx_) (&packets[idx_]->po_bwp_state->bwps_send_state)
// Ack packet 1.
assert(PacketsToBytes(1) == SEND_STATE(1)->total_bytes_sent);
assert(0 == SEND_STATE(1)->total_bytes_acked);
assert(0 == SEND_STATE(1)->total_bytes_lost);
sample = sampler_test_ack_packet(&stest, packets[1]);
assert(sample);
lsquic_malo_put(sample);
assert(PacketsToBytes(1) == stest.sampler.bws_total_acked);
// Lose packet 2.
assert(PacketsToBytes(2) == SEND_STATE(2)->total_bytes_sent);
assert(0 == SEND_STATE(2)->total_bytes_acked);
assert(0 == SEND_STATE(2)->total_bytes_lost);
sampler_test_lose_packet(&stest, packets[2]);
assert(PacketsToBytes(1) == stest.sampler.bws_total_lost);
// Lose packet 3.
assert(PacketsToBytes(3) == SEND_STATE(3)->total_bytes_sent);
assert(0 == SEND_STATE(3)->total_bytes_acked);
assert(0 == SEND_STATE(3)->total_bytes_lost);
sampler_test_lose_packet(&stest, packets[3]);
assert(PacketsToBytes(2) == stest.sampler.bws_total_lost);
// Send packets 6-10.
for (i = 6; i <= 10; i++)
{
packets[i] = sampler_test_send_packet(&stest, i, true);
assert(PacketsToBytes(i) == stest.sampler.bws_total_sent);
stest.time += time_between_packets;
}
// Ack all inflight packets.
unsigned acked_packet_count = 1;
assert(PacketsToBytes(acked_packet_count) ==
stest.sampler.bws_total_acked);
for (i = 4; i <= 10; i++)
{
assert(PacketsToBytes(i) == SEND_STATE(i)->total_bytes_sent);
if (i <= 5)
{
assert(0 == SEND_STATE(i)->total_bytes_acked);
assert(0 == SEND_STATE(i)->total_bytes_lost);
}
else
{
assert(PacketsToBytes(1) == SEND_STATE(i)->total_bytes_acked);
assert(PacketsToBytes(2) == SEND_STATE(i)->total_bytes_lost);
}
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
lsquic_malo_put(sample);
++acked_packet_count;
assert(PacketsToBytes(acked_packet_count) ==
stest.sampler.bws_total_acked);
stest.time += time_between_packets;
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
sampler_test_cleanup(&stest);
}
// Test the sampler during regular windowed sender scenario with fixed
// CWND of 20.
static void
test_send_paced (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize);
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[41];
sampler_test_init(&stest);
sampler_test_send_40_packets_and_ack_first_20(&stest,
time_between_packets, packets);
// Ack the packets 21 to 40, arriving at the correct bandwidth.
for (i = 21; i <= 40; ++i)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Test the sampler in a scenario where 50% of packets is consistently lost.
static void
test_send_with_losses (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize) / 2;
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[41];
sampler_test_init(&stest);
// Send 20 packets, each 1 ms apart.
for (i = 1; i <= 20; i++)
{
packets[i] = sampler_test_send_packet(&stest, i, true);
stest.time += time_between_packets;
}
// Ack packets 1 to 20, losing every even-numbered packet, while sending new
// packets at the same rate as before.
for (i = 1; i <= 20; i++)
{
if (i % 2 == 0)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
lsquic_malo_put(sample);
}
else
sampler_test_lose_packet(&stest, packets[i]);
packets[i + 20] = sampler_test_send_packet(&stest, i + 20, true);
stest.time += time_between_packets;
}
// Ack the packets 21 to 40 with the same loss pattern.
for (i = 21; i <= 40; i++)
{
if (i % 2 == 0)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
lsquic_malo_put(sample);
}
else
sampler_test_lose_packet(&stest, packets[i]);
stest.time += time_between_packets;
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Test the sampler in a scenario where the 50% of packets are not
// congestion controlled (specifically, non-retransmittable data is not
// congestion controlled). Should be functionally consistent in behavior with
// the SendWithLosses test.
static void
test_not_congestion_controlled (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize) / 2;
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[41];
sampler_test_init(&stest);
/* Note the mismatch between the comment and the code. This is
* inherited from the original code.
*/
// Send 20 packets, each 1 ms apart. Every even packet is not congestion
// controlled.
for (i = 1; i <= 20; i++)
{
packets[i] = sampler_test_send_packet(&stest, i,
i % 2 == 0 ? true : false);
stest.time += time_between_packets;
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 10);
// Ack packets 2 to 21, ignoring every even-numbered packet, while sending new
// packets at the same rate as before.
for (i = 1; i <= 20; i++)
{
if (i % 2 == 0)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
lsquic_malo_put(sample);
}
packets[i + 20] = sampler_test_send_packet(&stest, i + 20,
i % 2 == 0 ? true : false);
stest.time += time_between_packets;
}
// Ack the packets 22 to 41 with the same congestion controlled pattern.
for (i = 21; i <= 40; i++)
{
if (i % 2 == 0)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
lsquic_malo_put(sample);
}
stest.time += time_between_packets;
}
// Since only congestion controlled packets are entered into the map, it has
// to be empty at this point.
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Simulate a situation where ACKs arrive in burst and earlier than usual, thus
// producing an ACK rate which is higher than the original send rate.
static void
test_compressed_ack (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1),
ridiculously_small_time_delta = us(20);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize);
uint64_t bw;
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[41];
sampler_test_init(&stest);
sampler_test_send_40_packets_and_ack_first_20(&stest,
time_between_packets, packets);
// Simulate an RTT somewhat lower than the one for 1-to-21 transmission.
stest.time += time_between_packets * 15;
// Ack the packets 21 to 40 almost immediately at once.
for (i = 21; i <= 40; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
stest.time += ridiculously_small_time_delta;
bw = BW_VALUE(&sample->bandwidth);
lsquic_malo_put(sample);
}
assert(bw == expected_bw);
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Tests receiving ACK packets in the reverse order.
static void
test_reordered_ack (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize);
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[61];
sampler_test_init(&stest);
sampler_test_send_40_packets_and_ack_first_20(&stest,
time_between_packets, packets);
// Ack the packets 21 to 40 in the reverse order, while sending packets 41 to
// 60.
for (i = 0; i < 20; i++)
{
sample = sampler_test_ack_packet(&stest, packets[40 - i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
packets[41 + i] = sampler_test_send_packet(&stest, 41 + i, true);
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
// Ack the packets 41 to 60, now in the regular order.
for (i = 41; i <= 60; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Test the app-limited logic.
static void
test_app_limited (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1);
uint64_t expected_bw = FromKBytesPerSecond(kRegularPacketSize);
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[81];
sampler_test_init(&stest);
sampler_test_send_40_packets_and_ack_first_20(&stest,
time_between_packets, packets);
// We are now app-limited. Ack 21 to 40 as usual, but do not send anything for
// now.
lsquic_bw_sampler_app_limited(&stest.sampler);
for (i = 21; i <= 40; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(expected_bw == BW_VALUE(&sample->bandwidth));
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
stest.time += sec(1);
// Send packets 41 to 60, all of which would be marked as app-limited.
for (i = 41; i <= 60; i++)
{
packets[i] = sampler_test_send_packet(&stest, i, true);
stest.time += time_between_packets;
}
// Ack packets 41 to 60, while sending packets 61 to 80. 41 to 60 should be
// app-limited and underestimate the bandwidth due to that.
for (i = 41; i <= 60; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(sample->is_app_limited);
assert(BW_VALUE(&sample->bandwidth) < 0.7 * expected_bw);
packets[i + 20] = sampler_test_send_packet(&stest, i + 20, true);
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
// Run out of packets, and then ack packet 61 to 80, all of which should have
// correct non-app-limited samples.
for (i = 61; i <= 80; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(BW_VALUE(&sample->bandwidth) == expected_bw);
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
assert(lsquic_bw_sampler_entry_count(&stest.sampler) == 0);
assert(stest.bytes_in_flight == 0);
sampler_test_cleanup(&stest);
}
// Test the samples taken at the first flight of packets sent.
static void
test_first_round_trip (void)
{
struct sampler_test stest;
const lsquic_time_t time_between_packets = ms(1),
rtt = ms(800);
const unsigned num_packets = 10;
const uint64_t num_bytes = num_packets * kRegularPacketSize;
struct bandwidth real_bandwidth = BW_FROM_BYTES_AND_DELTA(num_bytes, rtt);
uint64_t last_bw;
unsigned i;
struct bw_sample *sample;
struct lsquic_packet_out *packets[11];
sampler_test_init(&stest);
for (i = 1; i <= 10; i++)
{
packets[i] = sampler_test_send_packet(&stest, i, true);
stest.time += time_between_packets;
}
stest.time += rtt - num_packets * time_between_packets;
last_bw = 0;
for (i = 1; i <= 10; i++)
{
sample = sampler_test_ack_packet(&stest, packets[i]);
assert(sample);
assert(BW_VALUE(&sample->bandwidth) > last_bw);
last_bw = BW_VALUE(&sample->bandwidth);
stest.time += time_between_packets;
lsquic_malo_put(sample);
}
// The final measured sample for the first flight of sample is expected to be
// smaller than the real bandwidth, yet it should not lose more than 10%. The
// specific value of the error depends on the difference between the RTT and
// the time it takes to exhaust the congestion window (i.e. in the limit when
// all packets are sent simultaneously, last sample would indicate the real
// bandwidth).
assert(last_bw < real_bandwidth.value);
assert(last_bw > 0.9f * real_bandwidth.value);
sampler_test_cleanup(&stest);
}
int
main (void)
{
test_send_and_wait();
test_send_time_state();
test_send_paced();
test_send_with_losses();
test_not_congestion_controlled();
test_compressed_ack();
test_reordered_ack();
test_app_limited();
test_first_round_trip();
return 0;
}