Author: Armin Rigo <ar...@tunes.org>
Branch: stm
Changeset: r52629:df6f7424b1d3
Date: 2012-02-19 12:35 +0100
http://bitbucket.org/pypy/pypy/changeset/df6f7424b1d3/
Log: A version of the cache that models a hardware L1 cache. (disabled by
default because it's buggy in subtle cases)
diff --git a/pypy/translator/stm/src_stm/associative.c
b/pypy/translator/stm/src_stm/associative.c
new file mode 100644
--- /dev/null
+++ b/pypy/translator/stm/src_stm/associative.c
@@ -0,0 +1,81 @@
+
+/* parameters taken from my laptop's Core i5, tweaked according to
+ * http://en.wikipedia.org/wiki/Haswell_%28microarchitecture%29
+ *
+ * this is not an optimized implementation at all. just for measuring
+ * the number of collisions that we get on some examples.
+ */
+
+
+#define HWEMULATOR_ASSOCIATIVITY_BITS 3 /* = 8 */
+#define HWEMULATOR_CACHE_LINE_BITS 7 /* = 128 */
+#define HWEMULATOR_NUMBER_OF_SETS_BITS 6 /* = 64 */
+
+/* this defines a cache size of 64 KB == 1 << (sum of the three numbers) */
+
+
+
+typedef struct {
+ char data[1 << HWEMULATOR_CACHE_LINE_BITS];
+ long tag;
+ unsigned long creation;
+} cacheline_t;
+
+typedef struct {
+ cacheline_t choices[1 << HWEMULATOR_ASSOCIATIVITY_BITS];
+} cacheset_t;
+
+static cacheset_t hwemulator_orecs[1 << HWEMULATOR_NUMBER_OF_SETS_BITS];
+
+
+static orec_t *get_orec(void* addr)
+{
+ /* find the set number */
+ int setnum = (((long)addr) >> HWEMULATOR_CACHE_LINE_BITS) &
+ ((1 << HWEMULATOR_NUMBER_OF_SETS_BITS) - 1);
+
+ /* grab it */
+ cacheset_t *set = &hwemulator_orecs[setnum];
+
+ /* round down the addr to get the tag */
+ long tag = ((long)addr) >> HWEMULATOR_CACHE_LINE_BITS;
+
+ /* is the cacheline already in the set? */
+ int i;
+ cacheline_t *line;
+ for (i=0; i < (1 << HWEMULATOR_ASSOCIATIVITY_BITS); i++) {
+ line = &set->choices[i];
+ if (line->tag == tag)
+ goto found;
+ }
+
+ /* find the oldest cacheline in the set */
+ cacheline_t *oldest_line = 0;
+ unsigned long oldest = (unsigned long) -1;
+ unsigned long youngest = 0;
+ for (i=0; i < (1 << HWEMULATOR_ASSOCIATIVITY_BITS); i++) {
+ line = &set->choices[i];
+ if (line->creation < oldest) {
+ oldest = line->creation;
+ oldest_line = line;
+ }
+ if (line->creation > youngest)
+ youngest = line->creation;
+ }
+
+ /* replace it */
+ line = oldest_line;
+ line->tag = tag;
+ line->creation = youngest + 1;
+ /* XXX this is wrong!! it can evict a line containing relevant data,
+ which can then be recreated at a different index! The issue is
+ that this operation may forget that we did some changes! But
+ it's probably good enough for now just to measure the effect */
+
+ found:;
+ /* return the orec_t that is in line->data at the correct offset */
+ assert((((long)addr) & (sizeof(orec_t)-1)) == 0);
+ char *p = line->data + (((long)addr) &
+ ((1 << HWEMULATOR_CACHE_LINE_BITS) - 1));
+ return (orec_t *)p;
+}
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
@@ -36,6 +36,10 @@
typedef volatile owner_version_t orec_t;
+/*#define USE_ASSOCIATIVE_CACHE*/
+
+#ifndef USE_ASSOCIATIVE_CACHE /* simple version */
+
/*** Specify the number of orecs in the global array. */
#define NUM_STRIPES 1048576
@@ -53,6 +57,10 @@
return (orec_t *)p;
}
+#else /* USE_ASSOCIATIVE_CACHE: follows more closely what hardware would do */
+# include "src_stm/associative.c"
+#endif
+
#include "src_stm/lists.c"
/************************************************************/
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