Author: Armin Rigo <[email protected]>
Branch: stm-thread-2
Changeset: r60046:b0df504dfd7b
Date: 2013-01-14 09:48 +0100
http://bitbucket.org/pypy/pypy/changeset/b0df504dfd7b/
Log: Trying to implement the idea of decreasing the limit more subtly:
set it to 94% of the read size at the point the abort occurred.
(This is what I meant, and not f3d388a6c22d from stm-logging.)
Measures needed.
diff --git a/pypy/translator/stm/src_stm/et.c b/pypy/translator/stm/src_stm/et.c
--- a/pypy/translator/stm/src_stm/et.c
+++ b/pypy/translator/stm/src_stm/et.c
@@ -367,6 +367,7 @@
static void AbortTransaction(int num)
{
struct tx_descriptor *d = thread_descriptor;
+ long limit;
assert(d->active);
assert(!is_inevitable(d));
assert(num < ABORT_REASONS);
@@ -374,6 +375,15 @@
CancelLocks(d);
+ /* upon abort, set the reads size limit to 94% of how much was read
+ so far. This should ensure that, assuming the retry does the same
+ thing, it will commit just before it reaches the conflicting point. */
+ limit = d->list_of_read_objects.size;
+ if (limit > 0) {
+ limit -= (limit >> 4);
+ d->reads_size_limit_nonatomic = limit;
+ }
+
gcptrlist_clear(&d->list_of_read_objects);
gcptrlist_clear(&d->gcroots);
g2l_clear(&d->global_to_local);
diff --git a/pypy/translator/stm/src_stm/rpyintf.c
b/pypy/translator/stm/src_stm/rpyintf.c
--- a/pypy/translator/stm/src_stm/rpyintf.c
+++ b/pypy/translator/stm/src_stm/rpyintf.c
@@ -154,12 +154,19 @@
do
{
v_counter = counter + 1;
- /* initialize 'reads_size_limit_nonatomic' from the configured
- length limit, scaled down by a factor of 2 for each time we
- retry an aborted transaction. Note that as soon as such a
- shortened transaction succeeds, the next one will again have
- full length, for now. */
- d->reads_size_limit_nonatomic = stm_regular_length_limit >> counter;
+ /* If counter==0, initialize 'reads_size_limit_nonatomic' from the
+ configured length limit. If counter>0, we did an abort, which
+ has configured 'reads_size_limit_nonatomic' to a smaller value.
+ When such a shortened transaction succeeds, the next one will
+ see its length limit doubled, up to the maximum. */
+ if (counter == 0) {
+ long limit = d->reads_size_limit_nonatomic;
+ if (limit != 0 && limit < (stm_regular_length_limit >> 1))
+ limit = (limit << 1) | 1;
+ else
+ limit = stm_regular_length_limit;
+ d->reads_size_limit_nonatomic = limit;
+ }
if (!d->atomic)
BeginTransaction(&_jmpbuf);
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