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Use a non-stupid data structure in the scheduler

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This commit is contained in:
Andrea Shepard 2013-12-12 04:22:53 -08:00
parent 3530825c53
commit ed1927d6bf
2 changed files with 139 additions and 58 deletions
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3
src/or/channel.h
View File

@ -80,6 +80,9 @@ struct channel_s {
SCHED_CHAN_PENDING
} scheduler_state;
/** Heap index for use by the scheduler */
int sched_heap_idx;
/** Timestamps for both cell channels and listeners */
time_t timestamp_created; /* Channel created */
time_t timestamp_active; /* Any activity */

194
src/or/scheduler.c
View File

@ -23,6 +23,14 @@
#define SCHED_Q_LOW_WATER 16384
#define SCHED_Q_HIGH_WATER (2 * SCHED_Q_LOW_WATER)
/*
* Maximum cells to flush in a single call to channel_flush_some_cells();
* setting this low means more calls, but too high and we could overshoot
* SCHED_Q_HIGH_WATER.
*/
#define SCHED_MAX_FLUSH_CELLS 16
/*
* Write scheduling works by keeping track of which channels can
* accept cells, and have cells to write. From the scheduler's perspective,
@ -100,7 +108,7 @@
* is reserved for our use.
*/
/* List of channels that can write and have cells (pending work) */
/* Pqueue of channels that can write and have cells (pending work) */
static smartlist_t *channels_pending = NULL;
/*
@ -125,7 +133,7 @@ static time_t queue_heuristic_timestamp = 0;
/* Scheduler static function declarations */
static int scheduler_compare_channels(const void **c1_v, const void **c2_v);
static int scheduler_compare_channels(const void *c1_v, const void *c2_v);
static void scheduler_evt_callback(evutil_socket_t fd,
short events, void *arg);
static int scheduler_more_work(void);
@ -162,7 +170,7 @@ scheduler_free_all(void)
*/
static int
scheduler_compare_channels(const void **c1_v, const void **c2_v)
scheduler_compare_channels(const void *c1_v, const void *c2_v)
{
channel_t *c1 = NULL, *c2 = NULL;
/* These are a workaround for -Wbad-function-cast throwing a fit */
@ -172,8 +180,8 @@ scheduler_compare_channels(const void **c1_v, const void **c2_v)
tor_assert(c1_v);
tor_assert(c2_v);
c1 = (channel_t *)(*c1_v);
c2 = (channel_t *)(*c2_v);
c1 = (channel_t *)(c1_v);
c2 = (channel_t *)(c2_v);
tor_assert(c1);
tor_assert(c2);
@ -241,7 +249,10 @@ scheduler_channel_doesnt_want_writes(channel_t *chan)
* the other lists. It can't write any more, so it goes to
* channels_waiting_to_write.
*/
smartlist_remove(channels_pending, chan);
smartlist_pqueue_remove(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx),
chan);
chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE;
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p went from pending "
@ -280,7 +291,10 @@ scheduler_channel_has_waiting_cells(channel_t *chan)
* channels_pending.
*/
chan->scheduler_state = SCHED_CHAN_PENDING;
smartlist_add(channels_pending, chan);
smartlist_pqueue_add(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx),
chan);
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p went from waiting_for_cells "
"to pending",
@ -353,7 +367,10 @@ scheduler_release_channel(channel_t *chan)
tor_assert(channels_pending);
if (chan->scheduler_state == SCHED_CHAN_PENDING) {
smartlist_remove(channels_pending, chan);
smartlist_pqueue_remove(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx),
chan);
}
chan->scheduler_state = SCHED_CHAN_IDLE;
@ -364,10 +381,11 @@ scheduler_release_channel(channel_t *chan)
void
scheduler_run(void)
{
smartlist_t *tmp = NULL;
int n_cells, n_chans_before, n_chans_after;
uint64_t q_len_before, q_heur_before, q_len_after, q_heur_after;
ssize_t flushed, flushed_this_time;
smartlist_t *to_readd = NULL;
channel_t *chan = NULL;
log_debug(LD_SCHED, "We have a chance to run the scheduler");
@ -375,61 +393,118 @@ scheduler_run(void)
n_chans_before = smartlist_len(channels_pending);
q_len_before = channel_get_global_queue_estimate();
q_heur_before = scheduler_get_queue_heuristic();
tmp = channels_pending;
channels_pending = smartlist_new();
/*
* UGLY HACK: sort the list on each invocation
*
* TODO smarter data structures
*/
smartlist_sort(tmp, scheduler_compare_channels);
while (scheduler_get_queue_heuristic() <= SCHED_Q_HIGH_WATER &&
smartlist_len(channels_pending) > 0) {
/* Pop off a channel */
chan = smartlist_pqueue_pop(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx));
tor_assert(chan);
SMARTLIST_FOREACH_BEGIN(tmp, channel_t *, chan) {
if (scheduler_get_queue_heuristic() <= SCHED_Q_HIGH_WATER) {
n_cells = channel_num_cells_writeable(chan);
if (n_cells > 0) {
/* Figure out how many cells we can write */
n_cells = channel_num_cells_writeable(chan);
if (n_cells > 0) {
log_debug(LD_SCHED,
"Scheduler saw pending channel " U64_FORMAT " at %p with "
"%d cells writeable",
U64_PRINTF_ARG(chan->global_identifier), chan, n_cells);
flushed = 0;
while (flushed < n_cells &&
scheduler_get_queue_heuristic() <= SCHED_Q_HIGH_WATER) {
flushed_this_time =
channel_flush_some_cells(chan,
MIN(SCHED_MAX_FLUSH_CELLS,
n_cells - flushed));
if (flushed_this_time <= 0) break;
flushed += flushed_this_time;
}
if (flushed < n_cells) {
/* We ran out of cells to flush */
chan->scheduler_state = SCHED_CHAN_WAITING_FOR_CELLS;
log_debug(LD_SCHED,
"Scheduler saw pending channel " U64_FORMAT " at %p with "
"%d cells writeable",
U64_PRINTF_ARG(chan->global_identifier), chan, n_cells);
flushed = 0;
while (flushed < n_cells) {
flushed_this_time =
channel_flush_some_cells(chan, n_cells - flushed);
if (flushed_this_time <= 0) break;
flushed += flushed_this_time;
}
if (flushed < n_cells) {
/* We ran out of cells to flush */
chan->scheduler_state = SCHED_CHAN_WAITING_FOR_CELLS;
} else {
/* TODO get this right */
}
log_debug(LD_SCHED,
"Scheduler flushed %d cells onto pending channel "
U64_FORMAT " at %p",
(int)flushed, U64_PRINTF_ARG(chan->global_identifier),
"Channel " U64_FORMAT " at %p "
"entered waiting_for_cells from pending",
U64_PRINTF_ARG(chan->global_identifier),
chan);
} else {
log_info(LD_SCHED,
"Scheduler saw pending channel " U64_FORMAT " at %p with "
"no cells writeable",
U64_PRINTF_ARG(chan->global_identifier), chan);
/* Put it back to WAITING_TO_WRITE */
chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE;
/* The channel may still have some cells */
if (channel_more_to_flush(chan)) {
/* The channel goes to either pending or waiting_to_write */
if (channel_num_cells_writeable(chan) > 0) {
/* Add it back to pending later */
if (!to_readd) to_readd = smartlist_new();
smartlist_add(to_readd, chan);
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p "
"is still pending",
U64_PRINTF_ARG(chan->global_identifier),
chan);
} else {
/* It's waiting to be able to write more */
chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE;
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p "
"entered waiting_to_write from pending",
U64_PRINTF_ARG(chan->global_identifier),
chan);
}
} else {
/* No cells left; it can go to idle or waiting_for_cells */
if (channel_num_cells_writeable(chan) > 0) {
/*
* It can still accept writes, so it goes to
* waiting_for_cells
*/
chan->scheduler_state = SCHED_CHAN_WAITING_FOR_CELLS;
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p "
"entered waiting_for_cells from pending",
U64_PRINTF_ARG(chan->global_identifier),
chan);
} else {
/*
* We exactly filled up the output queue with all available
* cells; go to idle.
*/
chan->scheduler_state = SCHED_CHAN_IDLE;
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p "
"become idle from pending",
U64_PRINTF_ARG(chan->global_identifier),
chan);
}
}
}
} else {
/* Not getting it this round; put it back on the list */
smartlist_add(channels_pending, chan);
/* It states in SCHED_CHAN_PENDING */
}
} SMARTLIST_FOREACH_END(chan);
smartlist_free(tmp);
log_debug(LD_SCHED,
"Scheduler flushed %d cells onto pending channel "
U64_FORMAT " at %p",
(int)flushed, U64_PRINTF_ARG(chan->global_identifier),
chan);
} else {
log_info(LD_SCHED,
"Scheduler saw pending channel " U64_FORMAT " at %p with "
"no cells writeable",
U64_PRINTF_ARG(chan->global_identifier), chan);
/* Put it back to WAITING_TO_WRITE */
chan->scheduler_state = SCHED_CHAN_WAITING_TO_WRITE;
}
}
/* Readd any channels we need to */
if (to_readd) {
SMARTLIST_FOREACH_BEGIN(to_readd, channel_t *, chan) {
chan->scheduler_state = SCHED_CHAN_PENDING;
smartlist_pqueue_add(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx),
chan);
} SMARTLIST_FOREACH_END(chan);
smartlist_free(to_readd);
}
n_chans_after = smartlist_len(channels_pending);
q_len_after = channel_get_global_queue_estimate();
@ -473,7 +548,10 @@ scheduler_channel_wants_writes(channel_t *chan)
/*
* It can write now, so it goes to channels_pending.
*/
smartlist_add(channels_pending, chan);
smartlist_pqueue_add(channels_pending,
scheduler_compare_channels,
STRUCT_OFFSET(channel_t, sched_heap_idx),
chan);
chan->scheduler_state = SCHED_CHAN_PENDING;
log_debug(LD_SCHED,
"Channel " U64_FORMAT " at %p went from waiting_to_write "