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Turn cell queue watermark limits into consensus params.

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This allows us to have quicker reaction to blocked orconns as
a congestion signal.
This commit is contained in:
Mike Perry 2021-09-29 02:12:56 +00:00 committed by David Goulet
parent e9038dc5f2
commit 322f213210
3 changed files with 43 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
src/core/or/congestion_control_common.c
View File

@ -50,6 +50,9 @@
#define OR_CONN_HIGHWATER_DFLT (32*1024)
#define OR_CONN_LOWWATER_DFLT (16*1024)
#define CELL_QUEUE_LOW_DFLT (10)
#define CELL_QUEUE_HIGH_DFLT (256)
static uint64_t congestion_control_update_circuit_rtt(congestion_control_t *,
uint64_t);
static bool congestion_control_update_circuit_bdp(congestion_control_t *,
@ -61,6 +64,9 @@ static uint32_t cwnd_max = CWND_MAX_DFLT;
uint32_t or_conn_highwater = OR_CONN_HIGHWATER_DFLT;
uint32_t or_conn_lowwater = OR_CONN_LOWWATER_DFLT;
int32_t cell_queue_high = CELL_QUEUE_HIGH_DFLT;
int32_t cell_queue_low = CELL_QUEUE_LOW_DFLT;
/**
* Update global congestion control related consensus parameter values,
* every consensus update.
@ -68,6 +74,20 @@ uint32_t or_conn_lowwater = OR_CONN_LOWWATER_DFLT;
void
congestion_control_new_consensus_params(const networkstatus_t *ns)
{
#define CELL_QUEUE_HIGH_MIN (1)
#define CELL_QUEUE_HIGH_MAX (1000)
cell_queue_high = networkstatus_get_param(ns, "cellq_high",
CELL_QUEUE_HIGH_DFLT,
CELL_QUEUE_HIGH_MIN,
CELL_QUEUE_HIGH_MAX);
#define CELL_QUEUE_LOW_MIN (1)
#define CELL_QUEUE_LOW_MAX (1000)
cell_queue_low = networkstatus_get_param(ns, "cellq_low",
CELL_QUEUE_LOW_DFLT,
CELL_QUEUE_LOW_MIN,
CELL_QUEUE_LOW_MAX);
#define OR_CONN_HIGHWATER_MIN (CELL_PAYLOAD_SIZE)
#define OR_CONN_HIGHWATER_MAX (INT32_MAX)
or_conn_highwater =

20
src/core/or/congestion_control_common.h
View File

@ -43,10 +43,12 @@ bool is_monotime_clock_reliable(void);
void congestion_control_new_consensus_params(const networkstatus_t *ns);
/* Ugh, C.. these two are private. Use the getter instead, when
/* Ugh, C.. these four are private. Use the getter instead, when
* external to the congestion control code. */
extern uint32_t or_conn_highwater;
extern uint32_t or_conn_lowwater;
extern int32_t cell_queue_high;
extern int32_t cell_queue_low;
/** Stop writing on an orconn when its outbuf is this large */
static inline uint32_t
@ -62,6 +64,22 @@ or_conn_lowwatermark(void)
return or_conn_lowwater;
}
/** Stop reading on edge connections when we have this many cells
* waiting on the appropriate queue. */
static inline int32_t
cell_queue_highwatermark(void)
{
return cell_queue_high;
}
/** Start reading from edge connections again when we get down to this many
* cells. */
static inline int32_t
cell_queue_lowwatermark(void)
{
return cell_queue_low;
}
/**
* Compute an N-count EWMA, aka N-EWMA. N-EWMA is defined as:
* EWMA = alpha*value + (1-alpha)*EWMA_prev

15
src/core/or/relay.c
View File

@ -117,13 +117,6 @@ static void adjust_exit_policy_from_exitpolicy_failure(origin_circuit_t *circ,
node_t *node,
const tor_addr_t *addr);
/** Stop reading on edge connections when we have this many cells
* waiting on the appropriate queue. */
#define CELL_QUEUE_HIGHWATER_SIZE 256
/** Start reading from edge connections again when we get down to this many
* cells. */
#define CELL_QUEUE_LOWWATER_SIZE 64
/** Stats: how many relay cells have originated at this hop, or have
* been relayed onward (not recognized at this hop)?
*/
@ -2400,8 +2393,8 @@ circuit_resume_edge_reading_helper(edge_connection_t *first_conn,
or_circuit_t *or_circ = TO_OR_CIRCUIT(circ);
cells_on_queue = or_circ->p_chan_cells.n;
}
if (CELL_QUEUE_HIGHWATER_SIZE - cells_on_queue < max_to_package)
max_to_package = CELL_QUEUE_HIGHWATER_SIZE - cells_on_queue;
if (cell_queue_highwatermark() - cells_on_queue < max_to_package)
max_to_package = cell_queue_highwatermark() - cells_on_queue;
/* Once we used to start listening on the streams in the order they
* appeared in the linked list. That leads to starvation on the
@ -3121,7 +3114,7 @@ channel_flush_from_first_active_circuit, (channel_t *chan, int max))
/* Is the cell queue low enough to unblock all the streams that are waiting
* to write to this circuit? */
if (streams_blocked && queue->n <= CELL_QUEUE_LOWWATER_SIZE)
if (streams_blocked && queue->n <= cell_queue_lowwatermark())
set_streams_blocked_on_circ(circ, chan, 0, 0); /* unblock streams */
/* If n_flushed < max still, loop around and pick another circuit */
@ -3239,7 +3232,7 @@ append_cell_to_circuit_queue(circuit_t *circ, channel_t *chan,
/* If we have too many cells on the circuit, we should stop reading from
* the edge streams for a while. */
if (!streams_blocked && queue->n >= CELL_QUEUE_HIGHWATER_SIZE)
if (!streams_blocked && queue->n >= cell_queue_highwatermark())
set_streams_blocked_on_circ(circ, chan, 1, 0); /* block streams */
if (streams_blocked && fromstream) {