[tor-commits] [tor/master] Remove EWMA code from relay.{c,h}; it goes to a circuitmux policy now
andrea at torproject.org
andrea at torproject.org
Thu Oct 11 02:05:23 UTC 2012
commit 14fe0d585916f4d8fdba64b419778c47ffd64b16
Author: Andrea Shepard <andrea at torproject.org>
Date: Mon Oct 1 01:51:31 2012 -0700
Remove EWMA code from relay.{c,h}; it goes to a circuitmux policy now
---
src/or/relay.c | 332 --------------------------------------------------------
src/or/relay.h | 3 -
2 files changed, 0 insertions(+), 335 deletions(-)
diff --git a/src/or/relay.c b/src/or/relay.c
index e3b383b..d034162 100644
--- a/src/or/relay.c
+++ b/src/or/relay.c
@@ -10,7 +10,6 @@
* receiving from circuits, plus queuing on circuits.
**/
-#include <math.h>
#define RELAY_PRIVATE
#include "or.h"
#include "buffers.h"
@@ -1972,245 +1971,6 @@ cell_queue_pop(cell_queue_t *queue)
return cell;
}
-#if 0
-/** Helper for sorting cell_ewma_t values in their priority queue. */
-static int
-compare_cell_ewma_counts(const void *p1, const void *p2)
-{
- const cell_ewma_t *e1=p1, *e2=p2;
- if (e1->cell_count < e2->cell_count)
- return -1;
- else if (e1->cell_count > e2->cell_count)
- return 1;
- else
- return 0;
-}
-
-/** Given a cell_ewma_t, return a pointer to the circuit containing it. */
-static circuit_t *
-cell_ewma_to_circuit(cell_ewma_t *ewma)
-{
- if (ewma->is_for_p_chan) {
- /* This is an or_circuit_t's p_cell_ewma. */
- or_circuit_t *orcirc = SUBTYPE_P(ewma, or_circuit_t, p_cell_ewma);
- return TO_CIRCUIT(orcirc);
- } else {
- /* This is some circuit's n_cell_ewma. */
- return SUBTYPE_P(ewma, circuit_t, n_cell_ewma);
- }
-}
-
-/* ==== Functions for scaling cell_ewma_t ====
-
- When choosing which cells to relay first, we favor circuits that have been
- quiet recently. This gives better latency on connections that aren't
- pushing lots of data, and makes the network feel more interactive.
-
- Conceptually, we take an exponentially weighted mean average of the number
- of cells a circuit has sent, and allow active circuits (those with cells to
- relay) to send cells in reverse order of their exponentially-weighted mean
- average (EWMA) cell count. [That is, a cell sent N seconds ago 'counts'
- F^N times as much as a cell sent now, for 0<F<1.0, and we favor the
- circuit that has sent the fewest cells]
-
- If 'double' had infinite precision, we could do this simply by counting a
- cell sent at startup as having weight 1.0, and a cell sent N seconds later
- as having weight F^-N. This way, we would never need to re-scale
- any already-sent cells.
-
- To prevent double from overflowing, we could count a cell sent now as
- having weight 1.0 and a cell sent N seconds ago as having weight F^N.
- This, however, would mean we'd need to re-scale *ALL* old circuits every
- time we wanted to send a cell.
-
- So as a compromise, we divide time into 'ticks' (currently, 10-second
- increments) and say that a cell sent at the start of a current tick is
- worth 1.0, a cell sent N seconds before the start of the current tick is
- worth F^N, and a cell sent N seconds after the start of the current tick is
- worth F^-N. This way we don't overflow, and we don't need to constantly
- rescale.
- */
-
-/** How long does a tick last (seconds)? */
-#define EWMA_TICK_LEN 10
-
-/** The default per-tick scale factor, if it hasn't been overridden by a
- * 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
- * and <b>now</b>. Return the former and store the latter in
- * *<b>remainder_out</b>.
- *
- * These tick values are not meant to be shared between Tor instances, or used
- * for other purposes. */
-static unsigned
-cell_ewma_tick_from_timeval(const struct timeval *now,
- double *remainder_out)
-{
- unsigned res = (unsigned) (now->tv_sec / EWMA_TICK_LEN);
- /* rem */
- double rem = (now->tv_sec % EWMA_TICK_LEN) +
- ((double)(now->tv_usec)) / 1.0e6;
- *remainder_out = rem / EWMA_TICK_LEN;
- return res;
-}
-
-/** Compute and return the current cell_ewma tick. */
-unsigned
-cell_ewma_get_tick(void)
-{
- return ((unsigned)approx_time() / EWMA_TICK_LEN);
-}
-
-/** 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.)
- */
-static double ewma_scale_factor = 0.1;
-/* DOCDOC ewma_enabled */
-static int ewma_enabled = 0;
-
-/*DOCDOC*/
-#define EPSILON 0.00001
-/*DOCDOC*/
-#define LOG_ONEHALF -0.69314718055994529
-
-/** Adjust the global cell scale factor based on <b>options</b> */
-void
-cell_ewma_set_scale_factor(const or_options_t *options,
- const networkstatus_t *consensus)
-{
- 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, "CircuitPriorityHalflifeMsec",
- -1, -1, INT32_MAX)) >= 0) {
- halflife = ((double)halflife_ms)/1000.0;
- source = "CircuitPriorityHalflifeMsec in consensus";
- } else {
- halflife = EWMA_DEFAULT_HALFLIFE;
- source = "Default value";
- }
-
- 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 %f per %d seconds",
- source, ewma_scale_factor, EWMA_TICK_LEN);
- }
-}
-
-/** Return the multiplier necessary to convert the value of a cell sent in
- * 'from_tick' to one sent in 'to_tick'. */
-static INLINE double
-get_scale_factor(unsigned from_tick, unsigned to_tick)
-{
- /* This math can wrap around, but that's okay: unsigned overflow is
- well-defined */
- int diff = (int)(to_tick - from_tick);
- return pow(ewma_scale_factor, diff);
-}
-
-/** Adjust the cell count of <b>ewma</b> so that it is scaled with respect to
- * <b>cur_tick</b> */
-static void
-scale_single_cell_ewma(cell_ewma_t *ewma, unsigned cur_tick)
-{
- double factor = get_scale_factor(ewma->last_adjusted_tick, cur_tick);
- ewma->cell_count *= factor;
- ewma->last_adjusted_tick = cur_tick;
-}
-
-/** Adjust the cell count of every active circuit on <b>chan</b> so
- * that they are scaled with respect to <b>cur_tick</b> */
-static void
-scale_active_circuits(channel_t *chan, unsigned cur_tick)
-{
- double factor;
-
- tor_assert(chan);
-
- factor =
- get_scale_factor(
- chan->active_circuit_pqueue_last_recalibrated,
- cur_tick);
- /** Ordinarily it isn't okay to change the value of an element in a heap,
- * but it's okay here, since we are preserving the order. */
- SMARTLIST_FOREACH_BEGIN(
- chan->active_circuit_pqueue,
- cell_ewma_t *, e) {
- tor_assert(e->last_adjusted_tick ==
- chan->active_circuit_pqueue_last_recalibrated);
- e->cell_count *= factor;
- e->last_adjusted_tick = cur_tick;
- } SMARTLIST_FOREACH_END(e);
- chan->active_circuit_pqueue_last_recalibrated = cur_tick;
-}
-
-/** Rescale <b>ewma</b> to the same scale as <b>chan</b>, and add it to
- * <b>chan</b>'s priority queue of active circuits */
-static void
-add_cell_ewma_to_chan(channel_t *chan, cell_ewma_t *ewma)
-{
- tor_assert(chan);
- tor_assert(ewma);
- tor_assert(ewma->heap_index == -1);
-
- scale_single_cell_ewma(
- ewma,
- chan->active_circuit_pqueue_last_recalibrated);
-
- smartlist_pqueue_add(chan->active_circuit_pqueue,
- compare_cell_ewma_counts,
- STRUCT_OFFSET(cell_ewma_t, heap_index),
- ewma);
-}
-
-/** Remove <b>ewma</b> from <b>chan</b>'s priority queue of active circuits */
-static void
-remove_cell_ewma_from_chan(channel_t *chan, cell_ewma_t *ewma)
-{
- tor_assert(chan);
- tor_assert(ewma);
- tor_assert(ewma->heap_index != -1);
-
- smartlist_pqueue_remove(chan->active_circuit_pqueue,
- compare_cell_ewma_counts,
- STRUCT_OFFSET(cell_ewma_t, heap_index),
- ewma);
-}
-
-/** Remove and return the first cell_ewma_t from chan's priority queue of
- * active circuits. Requires that the priority queue is nonempty. */
-static cell_ewma_t *
-pop_first_cell_ewma_from_chan(channel_t *chan)
-{
- tor_assert(chan);
-
- return smartlist_pqueue_pop(chan->active_circuit_pqueue,
- compare_cell_ewma_counts,
- STRUCT_OFFSET(cell_ewma_t, heap_index));
-}
-#endif
-
/**
* Update the number of cells available on the circuit's n_chan or p_chan's
* circuit mux.
@@ -2335,15 +2095,6 @@ channel_flush_from_first_active_circuit(channel_t *chan, int max)
int streams_blocked;
packed_cell_t *cell;
-#if 0
- /* The current (hi-res) time */
- struct timeval now_hires;
-
- /* The EWMA cell counter for the circuit we're flushing. */
- cell_ewma_t *cell_ewma = NULL;
- double ewma_increment = -1;
-#endif
-
/* Get the cmux */
tor_assert(chan);
tor_assert(chan->cmux);
@@ -2356,26 +2107,6 @@ channel_flush_from_first_active_circuit(channel_t *chan, int max)
if (!circ) break;
assert_cmux_ok_paranoid(chan);
-#if 0
- /* This will go in circuitmux_get_first_active_circuit() */
- /* See if we're doing the ewma circuit selection algorithm. */
- if (ewma_enabled) {
- unsigned tick;
- double fractional_tick;
- tor_gettimeofday_cached(&now_hires);
- tick = cell_ewma_tick_from_timeval(&now_hires, &fractional_tick);
-
- if (tick != chan->active_circuit_pqueue_last_recalibrated) {
- scale_active_circuits(chan, tick);
- }
-
- ewma_increment = pow(ewma_scale_factor, -fractional_tick);
-
- cell_ewma = smartlist_get(chan->active_circuit_pqueue, 0);
- circ = cell_ewma_to_circuit(cell_ewma);
- }
-#endif
-
if (circ->n_chan == chan) {
queue = &circ->n_chan_cells;
streams_blocked = circ->streams_blocked_on_n_chan;
@@ -2460,28 +2191,6 @@ channel_flush_from_first_active_circuit(channel_t *chan, int max)
if (streams_blocked && queue->n <= CELL_QUEUE_LOWWATER_SIZE)
set_streams_blocked_on_circ(circ, chan, 0, 0); /* unblock streams */
-#if 0
- if (cell_ewma) {
- cell_ewma_t *tmp;
- cell_ewma->cell_count += ewma_increment;
- /* We pop and re-add the cell_ewma_t here, not above, since we need to
- * re-add it immediately to keep the priority queue consistent with
- * the linked-list implementation */
- tmp = pop_first_cell_ewma_from_chan(chan);
- tor_assert(tmp == cell_ewma);
- add_cell_ewma_to_chan(chan, cell_ewma);
- }
- if (!ewma_enabled && circ != chan->active_circuits) {
- /* If this happens, the current circuit just got made inactive by
- * a call in connection_write_to_buf(). That's nothing to worry about:
- * circuit_make_inactive_on_conn() already advanced chan->active_circuits
- * for us.
- */
- assert_active_circuits_ok_paranoid(chan);
- goto done;
- }
-#endif
-
/* If n_flushed < max still, loop around and pick another circuit */
}
@@ -2636,47 +2345,6 @@ assert_circuit_mux_okay(channel_t *chan)
circuitmux_assert_okay(chan->cmux);
}
-#if 0
-/** Fail with an assert if the active circuits ring on <b>orconn</b> is
- * corrupt. */
-void
-assert_active_circuits_ok(channel_t *chan)
-{
- circuit_t *head = NULL, *cur = NULL;
- int n = 0;
-
- tor_assert(chan);
-
- cur = head = chan->active_circuits;
-
- if (! head)
- return;
- do {
- circuit_t *next = *next_circ_on_chan_p(cur, chan);
- circuit_t *prev = *prev_circ_on_chan_p(cur, chan);
- cell_ewma_t *ewma;
- tor_assert(next);
- tor_assert(prev);
- tor_assert(*next_circ_on_chan_p(prev, chan) == cur);
- tor_assert(*prev_circ_on_chan_p(next, chan) == cur);
- if (chan == cur->n_chan) {
- ewma = &cur->n_cell_ewma;
- tor_assert(!ewma->is_for_p_chan);
- } else {
- ewma = &TO_OR_CIRCUIT(cur)->p_cell_ewma;
- tor_assert(ewma->is_for_p_chan);
- }
- tor_assert(ewma->heap_index != -1);
- tor_assert(ewma == smartlist_get(chan->active_circuit_pqueue,
- ewma->heap_index));
- n++;
- cur = next;
- } while (cur != head);
-
- tor_assert(n == smartlist_len(chan->active_circuit_pqueue));
-}
-#endif
-
/** Return 1 if we shouldn't restart reading on this circuit, even if
* we get a SENDME. Else return 0.
*/
diff --git a/src/or/relay.h b/src/or/relay.h
index ef5074b..5759c51 100644
--- a/src/or/relay.h
+++ b/src/or/relay.h
@@ -60,9 +60,6 @@ int append_address_to_payload(uint8_t *payload_out, const tor_addr_t *addr);
const uint8_t *decode_address_from_payload(tor_addr_t *addr_out,
const uint8_t *payload,
int payload_len);
-unsigned cell_ewma_get_tick(void);
-void cell_ewma_set_scale_factor(const or_options_t *options,
- const networkstatus_t *consensus);
void circuit_clear_cell_queue(circuit_t *circ, channel_t *chan);
#ifdef RELAY_PRIVATE
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