Author: Tobias Weber <[email protected]>
Branch: c8-long-transactions
Changeset: r2039:1b47d69c4988
Date: 2017-04-10 11:06 +0200
http://bitbucket.org/pypy/stmgc/changeset/1b47d69c4988/
Log: Implement simple single thread mode that is activated if there are
two or less segments in use at transaction start and sets the
nursery mark to a large number, thereby reducing the number of
commits
diff --git a/c8/stm/core.c b/c8/stm/core.c
--- a/c8/stm/core.c
+++ b/c8/stm/core.c
@@ -1163,6 +1163,12 @@
if (repeat_count == 0) { /* else, 'nursery_mark' was already set
in abort_data_structures_from_segment_num() */
+ if (number_of_segments_in_use() <= 2) {
+ /* TODO two is a hack b/c benchmarks have a main thread */
+ start_single_thread_mode();
+ } else if (stm_single_thread_mode_active) {
+ end_single_thread_mode();
+ }
STM_SEGMENT->nursery_mark = ((stm_char *)_stm_nursery_start +
stm_fill_mark_nursery_bytes);
}
diff --git a/c8/stm/nursery.c b/c8/stm/nursery.c
--- a/c8/stm/nursery.c
+++ b/c8/stm/nursery.c
@@ -13,13 +13,24 @@
static uintptr_t _stm_nursery_start;
+static bool stm_single_thread_mode_active = false;
-#define DEFAULT_FILL_MARK_NURSERY_BYTES (NURSERY_SIZE / 4)
+#define SINGLE_THREAD_MODE_FILL_MARK_NURSERY_BYTES (NURSERY_SIZE * 9999)
+#define DEFAULT_FILL_MARK_NURSERY_BYTES (NURSERY_SIZE / 4)
uintptr_t stm_fill_mark_nursery_bytes = DEFAULT_FILL_MARK_NURSERY_BYTES;
/************************************************************/
+static void start_single_thread_mode(void) {
+ stm_single_thread_mode_active = true;
+ stm_fill_mark_nursery_bytes = SINGLE_THREAD_MODE_FILL_MARK_NURSERY_BYTES;
+}
+
+static void end_single_thread_mode(void) {
+ stm_fill_mark_nursery_bytes = DEFAULT_FILL_MARK_NURSERY_BYTES;
+ stm_single_thread_mode_active = false;
+}
static void setup_nursery(void)
{
diff --git a/c8/stm/nursery.h b/c8/stm/nursery.h
--- a/c8/stm/nursery.h
+++ b/c8/stm/nursery.h
@@ -9,6 +9,9 @@
static uint32_t highest_overflow_number;
+static void start_single_thread_mode(void);
+static void end_single_thread_mode(void);
+
static void _cards_cleared_in_object(struct stm_priv_segment_info_s *pseg,
object_t *obj,
bool strict);
static void _reset_object_cards(struct stm_priv_segment_info_s *pseg,
diff --git a/c8/stm/sync.c b/c8/stm/sync.c
--- a/c8/stm/sync.c
+++ b/c8/stm/sync.c
@@ -176,6 +176,16 @@
/************************************************************/
+static uint8_t number_of_segments_in_use(void) {
+ uint8_t result = 0;
+ int num;
+ for (num = 1; num < NB_SEGMENTS; num++) {
+ if (sync_ctl.in_use1[num] > 0) {
+ result++;
+ }
+ }
+ return result;
+}
#if 0
void stm_wait_for_current_inevitable_transaction(void)
@@ -202,7 +212,6 @@
}
#endif
-
static void acquire_thread_segment(stm_thread_local_t *tl)
{
/* This function acquires a segment for the currently running thread,
diff --git a/c8/stm/sync.h b/c8/stm/sync.h
--- a/c8/stm/sync.h
+++ b/c8/stm/sync.h
@@ -22,6 +22,7 @@
static void set_gs_register(char *value);
static void ensure_gs_register(long segnum);
+static uint8_t number_of_segments_in_use(void);
/* acquire and release one of the segments for running the given thread
(must have the mutex acquired!) */
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