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Implement configurable Adaptive ICMP idle delay
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Added the icmp_adaptive_idle_delay configuration option to control how long a connection has to be idle before Adaptive ICMP will switch to the idle ICMP interval.

Also fixed a problem where invalid ICMP results were only being marked as strikes if the connection was idle. They should always be marked as strikes.
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@tievolu
tievolu authored Sep 30, 2022
1 parent ef3a2c5 commit fa5b05f
Showing 1 changed file with 49 additions and 20 deletions.
69 changes: 49 additions & 20 deletions sqm-autorate.pl
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Original file line number Diff line number Diff line change
Expand Up @@ -271,6 +271,7 @@
my $relax_load_threshold_pc = &get_config_property("relax_load_threshold_pc", 50);
my $relax_delay = &get_config_property("relax_delay", 60);
my $icmp_adaptive = &get_config_property("icmp_adaptive", 1);
my $icmp_adaptive_idle_delay = &get_config_property("icmp_adaptive_idle_delay", 10);
my $icmp_interval_idle = &get_config_property("icmp_interval_idle", 1);
my $icmp_interval_loaded = &get_config_property("icmp_interval_loaded", &get_config_property("icmp_interval", 0.1));
my $icmp_timeout = &get_config_property("icmp_timeout", 1);
Expand Down Expand Up @@ -337,17 +338,19 @@
my $max_bad_pings = &round($max_recent_results * ($bad_ping_pc / 100)) - 1;

# Maximum number of historical bandwidth usage statistics samples to retain.
# Calculate the most we should need if everything works perfectly, and then round up
# and add a couple of additional samples to allow for timing variations.
# There's no performance impact here because we always search for a matching bandwidth
# sample period starting with the most recent result. Redundant samples at the other
# end of the array have no impact beyond a *tiny* increase in memory usage.
my $max_recent_bandwidth_usages;
if ($icmp_interval_idle > 0) {
$max_recent_bandwidth_usages = &round_up( ((($icmp_interval_idle * $max_recent_results) + $icmp_timeout) / $latency_check_interval) ) + 2;
} else {
$max_recent_bandwidth_usages = &round_up( ((($icmp_interval_loaded * $max_recent_results) + $icmp_timeout) / $latency_check_interval) ) + 2;
}
# We use these samples to check whether the connection is idle, and to check bandwidth
# usage at the time of each request and response, so we need to make sure we have enough
# samples for both.
#
# We calculate what should be the maximum number of samples required for each type of
# usage, plus a couple more to make sure, then select the largest number. Note that a
# couple of extra samples does not impact performance because we always search backwards
# starting with the most recent sample. Redundant samples at the end of the array have
# no impact beyond a *tiny* increase in memory usage.
my $max_for_adaptive_idle_delay = $icmp_adaptive ? &round_up($icmp_adaptive_idle_delay / $latency_check_interval) + 2 : 0;
my $max_icmp_interval = $icmp_interval_idle > $icmp_interval_loaded ? $icmp_interval_idle : $icmp_interval_loaded;
my $max_for_icmp_results = &round_up( ((($max_icmp_interval * $max_recent_results) + $icmp_timeout) / $latency_check_interval) ) + 2;
my $max_recent_bandwidth_usages = $max_for_icmp_results > $max_for_adaptive_idle_delay ? $max_for_icmp_results : $max_for_adaptive_idle_delay;

# Create an array to store the recent bandwidth usage statistics, and initialise it
my @recent_bandwidth_usages = ();
Expand Down Expand Up @@ -1069,6 +1072,11 @@ sub check_config {
$fatal_error = 1;
}

if ($icmp_adaptive_idle_delay <= $latency_check_interval) {
&output(0, "INIT: ERROR: Adaptive ICMP idle delay (\"icmp_adaptive_idle_delay\") must be greater than latency_check_interval ($latency_check_interval)");
$fatal_error = 1;
}

if ($icmp_interval_idle < 0) {
&output(0, "INIT: ERROR: ICMP interval (\"icmp_interval_idle\") cannot be less than 0");
$fatal_error = 1;
Expand All @@ -1094,6 +1102,11 @@ sub check_config {
$fatal_error = 1;
}

if ($status_summary_interval ne "auto" && $status_summary_interval < 0) {
&output(0, "INIT: ERROR: Status summary interval (\"status_summary_interval\") cannot be negative");
$fatal_error = 1;
}

if ($bad_ping_pc < 0 || $bad_ping_pc > 100) {
&output(0, "INIT: ERROR: Bad ping percentage (\"bad_ping_pc\") must be between 0 and 100");
$fatal_error = 1;
Expand Down Expand Up @@ -1556,7 +1569,7 @@ sub check_latency {
if ($icmp_interval_idle == 0) {
# Suspend ICMP threads if they're not already suspended, and return LATENCY_OK
if (!&are_icmp_threads_suspended()) {
if ($debug_icmp_adaptive) { &output(0, "ICMP ADAPTIVE DEBUG: Connection is idle - suspending ICMP threads"); }
if ($debug_icmp_adaptive) { &output(0, "ICMP ADAPTIVE DEBUG: Connection has been idle for $icmp_adaptive_idle_delay" . "s - suspending ICMP threads"); }

&suspend_icmp_threads();
&clear_latency_results();
Expand All @@ -1572,7 +1585,7 @@ sub check_latency {
my @summary_results = (0, 0, 0, 0, $ul_bw_ave, $dl_bw_ave, 0, 0);
return (LATENCY_OK, \@summary_results, \());
} elsif ($icmp_interval != $icmp_interval_idle) {
if ($debug_icmp_adaptive) { &output(0, "ICMP ADAPTIVE DEBUG: Connection is idle - setting ICMP interval to $icmp_interval_idle" . "s"); }
if ($debug_icmp_adaptive) { &output(0, "ICMP ADAPTIVE DEBUG: Connection has been idle for $icmp_adaptive_idle_delay" . "s - setting ICMP interval to $icmp_interval_idle" . "s"); }

lock ($icmp_interval);
$icmp_interval = $icmp_interval_idle;
Expand Down Expand Up @@ -1636,7 +1649,7 @@ sub check_latency {
# A strike is (by definition) a spurious bad result, so we mark the result as "good".
if ($reflector_strikeout_threshold != 0) { # if $reflector_strikeout_threshold == 0 strikes are disabled
if ($ul_time == ICMP_TIMED_OUT || $ul_time == ICMP_INVALID || $ul_time > $ul_max_idle_latency) {
if ($ul_bw < $ul_bw_idle_threshold) {
if ($ul_time == ICMP_INVALID || $ul_bw < $ul_bw_idle_threshold) {
&record_strike($ip, $packet_id, $seq, ($finish_time + $reflector_strike_ttl), "upload");
$ul_good = 1;
$ul_strike = 1;
Expand All @@ -1649,7 +1662,7 @@ sub check_latency {
$ul_strike = 0;
}
if ($dl_time == ICMP_TIMED_OUT || $dl_time == ICMP_INVALID || $dl_time > $dl_max_idle_latency) {
if ($dl_bw < $dl_bw_idle_threshold) {
if ($dl_time == ICMP_INVALID || $dl_bw < $dl_bw_idle_threshold) {
&record_strike($ip, $packet_id, $seq, ($finish_time + $reflector_strike_ttl), "download");
$dl_good = 1;
$dl_strike = 1;
Expand Down Expand Up @@ -2989,22 +3002,38 @@ sub get_bandwidth_usage_at {
&fatal_error("Failed to get $direction bandwidth at ". &format_time($time) . ". Earliest of " . scalar(@recent_bandwidth_usages) . " (max $max_recent_bandwidth_usages) bandwidth samples' start time = " . &format_time($earliest_start_time));
}

# Check whether the connection is idle in both directions
# Returns 1 if idle, 0 if loaded
# Check whether the connection has been idle in both directions for at least
# $icmp_adaptive_idle_delay seconds.
# Returns 1 if idle, 0 if loaded.
sub is_connection_idle {
my $start_time;
my $end_time;
my $bw_usage_ul;
my $bw_usage_dl;

# Calculate the lower limit on times we need to search
my $min_time = gettimeofday() - $icmp_adaptive_idle_delay;

# Bandwidth usage samples are ordered from newest -> oldest
# We want to search backwards until we hit a sample whose
# end time is greater than $min_time
foreach my $bw_usage_ref (@recent_bandwidth_usages) {
(undef, undef, $bw_usage_ul, $bw_usage_dl, undef, undef) = @{$bw_usage_ref};
if (defined($bw_usage_ul) && defined($bw_usage_dl)) {
($start_time, $end_time, $bw_usage_ul, $bw_usage_dl, undef, undef) = @{$bw_usage_ref};

if (defined($start_time) && $end_time > $min_time) {
if ($bw_usage_ul >= $ul_bw_idle_threshold || $bw_usage_dl >= $dl_bw_idle_threshold) {
# This sample indicates a loaded connection
return 0;
}
} else {
# If we reach here we've searched back as far as $icmp_adaptive_idle_delay
# and found no samples that indicate a loaded connection
return 1;
}
}

# If we reach here, none of the bandwidth samples indicates a loaded connection
# If we reach here we searched all of the bandwidth samples and none
# of them indicate a loaded connection
return 1;
}

Expand Down

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