Commit 60b01c6d authored by Nick Mathewson's avatar Nick Mathewson 👁
Browse files

Change interface for configuring cell ewma algorithm.

The rule is now: take the value from the CircuitPriorityHalflife
config option if it is set.  If it zero, disable the cell_ewma
algorithm.  If it is set, use it to calculate the scaling factor.
If it is not set, look for a CircPriorityHalflifeMsec parameter in the
consensus networkstatus.  If *that* is zero, then disable the cell_ewma
algorithm; if it is set, use it to calculate the scaling factor.
If it is not set at all, disable the algorithm.
parent 296381ed
......@@ -167,6 +167,7 @@ static config_var_t _option_vars[] = {
V(CircuitBuildTimeout, INTERVAL, "0"),
V(CircuitIdleTimeout, INTERVAL, "1 hour"),
V(CircuitStreamTimeout, INTERVAL, "0"),
V(CircuitPriorityHalflife, DOUBLE, "-100.0"), /*negative:'Use default'*/
V(ClientDNSRejectInternalAddresses, BOOL,"1"),
V(ClientOnly, BOOL, "0"),
V(ConsensusParams, STRING, NULL),
......@@ -212,6 +213,7 @@ static config_var_t _option_vars[] = {
V(ExitPolicyRejectPrivate, BOOL, "1"),
V(ExitPortStatistics, BOOL, "0"),
V(ExtraInfoStatistics, BOOL, "0"),
V(FallbackNetworkstatusFile, FILENAME,
SHARE_DATADIR PATH_SEPARATOR "tor" PATH_SEPARATOR "fallback-consensus"),
V(FascistFirewall, BOOL, "0"),
......@@ -356,10 +358,6 @@ static config_var_t _option_vars[] = {
NULL),
V(MinUptimeHidServDirectoryV2, INTERVAL, "24 hours"),
/* Options for EWMA selection of circuit to write from */
VAR("EWMASignificance", DOUBLE, EWMASignificance, "-1.0"),
VAR("EWMAInterval", DOUBLE, EWMAInterval, "-1.0"),
{ NULL, CONFIG_TYPE_OBSOLETE, 0, NULL }
};
......@@ -1380,7 +1378,7 @@ options_act(or_options_t *old_options)
configure_accounting(time(NULL));
/* Change the cell EWMA settings */
cell_ewma_set_scale_factor(options);
cell_ewma_set_scale_factor(options, networkstatus_get_latest_consensus());
/* Check for transitions that need action. */
if (old_options) {
......
......@@ -1679,6 +1679,7 @@ networkstatus_set_current_consensus(const char *consensus,
update_consensus_networkstatus_fetch_time(now);
dirvote_recalculate_timing(get_options(), now);
routerstatus_list_update_named_server_map();
cell_ewma_set_scale_factor(get_options(), current_consensus);
}
if (!from_cache) {
......
......@@ -2783,13 +2783,20 @@ typedef struct {
* to make this false. */
int ReloadTorrcOnSIGHUP;
/* The EWMA parameters for circuit selection within a connection.
* The most recent EWMAInterval seconds will account for an
* EWMASignificance (between 0 and 1) portion of the weight.
* If these values are negative, use the global defaults (soon to be
* set in the consensus). */
double EWMASignificance;
double EWMAInterval;
/* The main parameter for picking circuits within a connection.
*
* If this value is positive, when picking a cell to relay on a connection,
* we always relay from the circuit whose weighted cell count is lowest.
* Cells are weighted exponentially such that if one cell is sent
* 'CircuitPriorityHalflife' seconds before another, it counts for half as
* much.
*
* If this value is zero, we're disabling the cell-EWMA algorithm.
*
* If this value is negative, we're using the default approach
* according to either Tor or a parameter set in the consensus.
*/
double CircuitPriorityHalflife;
} or_options_t;
......@@ -4491,7 +4498,8 @@ const char *decode_address_from_payload(tor_addr_t *addr_out,
const char *payload,
int payload_len);
unsigned cell_ewma_get_tick(void);
void cell_ewma_set_scale_factor(or_options_t *options);
void cell_ewma_set_scale_factor(or_options_t *options,
networkstatus_t *consensus);
/********************************* rephist.c ***************************/
......
......@@ -1814,8 +1814,8 @@ cell_ewma_to_circuit(cell_ewma_t *ewma)
#define EWMA_TICK_LEN 10
/** The default per-tick scale factor, if it hasn't been overridden by a
* consensus or a configuration setting. */
#define EWMA_DEFAULT_SCALE_FACTOR 0.9
* consensus or a configuration setting. zero means "disabled". */
#define EWMA_DEFAULT_HALFLIFE 0.0
/** Given a timeval <b>now</b>, compute the cell_ewma tick in which it occurs
* and the fraction of the tick that has elapsed between the start of the tick
......@@ -1846,24 +1846,51 @@ cell_ewma_get_tick(void)
/** The per-tick scale factor to be used when computing cell-count EWMA
* values. (A cell sent N ticks before the start of the current tick
* has value ewma_scale_factor ** N.)
*
* If ewma_scale_factor is <= 0, the EWMA algorithm is disabled.
*/
static double ewma_scale_factor = EWMA_DEFAULT_SCALE_FACTOR;
static double ewma_scale_factor = 0.1;
static int ewma_enabled = 0;
#define EPSILON 0.00001
#define LOG_ONEHALF -0.69314718055994529
/** Adjust the global cell scale factor based on <b>options</b> */
void
cell_ewma_set_scale_factor(or_options_t *options)
cell_ewma_set_scale_factor(or_options_t *options, networkstatus_t *consensus)
{
double f;
if (options->EWMAInterval > 0.0001) {
f = pow(options->EWMASignificance,
EWMA_TICK_LEN / options->EWMAInterval);
int32_t halflife_ms;
double halflife;
const char *source;
if (options && options->CircuitPriorityHalflife >= -EPSILON) {
halflife = options->CircuitPriorityHalflife;
source = "CircuitPriorityHalflife in configuration";
} else if (consensus &&
(halflife_ms = networkstatus_get_param(
consensus, "CircPriorityHalflifeMsec", -1) >= 0)) {
halflife = ((double)halflife_ms)/1000.0;
source = "CircPriorityHalflifeMsec in consensus";
} else {
f = EWMA_DEFAULT_SCALE_FACTOR;
halflife = EWMA_DEFAULT_HALFLIFE;
source = "Default value";
}
ewma_scale_factor = f;
if (halflife <= EPSILON) {
/* The cell EWMA algorithm is disabled. */
ewma_scale_factor = 0.1;
ewma_enabled = 0;
log_info(LD_OR,
"Disabled cell_ewma algorithm because of value in %s",
source);
} else {
/* convert halflife into halflife-per-tick. */
halflife /= EWMA_TICK_LEN;
/* compute per-tick scale factor. */
ewma_scale_factor = exp( LOG_ONEHALF / halflife );
ewma_enabled = 1;
log_info(LD_OR,
"Enabled cell_ewma algorithm because of value in %s; "
"scale factor is %lf per %d seconds",
source, ewma_scale_factor, EWMA_TICK_LEN);
}
}
/** Return the multiplier necessary to convert the value of a cell sent in
......@@ -2108,7 +2135,7 @@ connection_or_flush_from_first_active_circuit(or_connection_t *conn, int max,
assert_active_circuits_ok_paranoid(conn);
/* See if we're doing the ewma circuit selection algorithm. */
if (ewma_scale_factor > 0.0) {
if (ewma_enabled) {
unsigned tick;
double fractional_tick;
tor_gettimeofday_cached(&now_hires);
......
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